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a319d13bee
esqueleto/src/Database/Esqueleto/Internal/Internal.hs
Ben Levy a319d13bee
[Experimental] More powerful queries (#215) 
* Initial attempt at Lateral joins

* Fix lateral queries for Inner and Left joins. Remove for Full and Right as this is apparently illegal(who knew). Add TypeError on Full and Right joins. Update on clause to use a custom constraint instead of relying on ToFrom.

* Fix typo leading to erroneous ToFrom instance

* Implement non-recursive CTE's

* add withRecursive; cleanup whitespace

* Fix multiple recursive CTEs. Apparently the spec just wants RECURSIVE if any of the queries are recursive.

* Add test to verify that a CTE can reference a previously defined CTE

* Update with/Recursive to return an element of a from clause to allow for joins against CTEs

* Modify set operations to use a custom data type + typeclass + typefamily to allow direct use of SqlQuery a in set operation and to allow recursive cte's to unify syntax with SqlSetOperation. Added lowercase names for set operations. If we can migrate off the constructor names we may be able to simplify the implementation.

* Fixed haddock documentation issue from v3.3.4.0 and added documentation
for new features introduced by v3.4.0.0

* fixed comments that were changed while debugging haddock build

* Cleanup formatting in From per PR. Cleanup ValidOnClause, added documentation and reduced the number of instances

* Update src/Database/Esqueleto/Experimental.hs

Co-authored-by: charukiewicz <charukiewicz@protonmail.com>
Co-authored-by: Matt Parsons <parsonsmatt@gmail.com>
2020-10-28 21:37:17 -06:00

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{-# LANGUAGE DeriveDataTypeable
, EmptyDataDecls
, FlexibleContexts
, FlexibleInstances
, FunctionalDependencies
, MultiParamTypeClasses
, TypeFamilies
, UndecidableInstances
, GADTs
#-}
{-# LANGUAGE ConstraintKinds
, EmptyDataDecls
, FlexibleContexts
, FlexibleInstances
, FunctionalDependencies
, GADTs
, MultiParamTypeClasses
, OverloadedStrings
, UndecidableInstances
, ScopedTypeVariables
, InstanceSigs
, Rank2Types
, CPP
#-}
-- | This is an internal module, anything exported by this module
-- may change without a major version bump. Please use only
-- "Database.Esqueleto" if possible.
--
-- If you use this module, please report what your use case is on the issue
-- tracker so we can safely support it.
module Database.Esqueleto.Internal.Internal where
import Control.Applicative ((<|>))
import Control.Arrow ((***), first)
import Control.Exception (Exception, throw, throwIO)
import qualified Data.Maybe as Maybe
import Control.Monad (guard, ap, MonadPlus(..), void)
import Control.Monad.IO.Class (MonadIO(..))
import Control.Monad.Trans.Class (lift)
import Control.Monad.Trans.Resource (MonadResource, release)
import Data.Acquire (with, allocateAcquire, Acquire)
import Data.Int (Int64)
import Data.List (intersperse)
#if __GLASGOW_HASKELL__ < 804
import Data.Semigroup
#endif
import qualified Data.Monoid as Monoid
import Data.Proxy (Proxy(..))
import Database.Esqueleto.Internal.PersistentImport
import qualified Database.Persist
import Database.Persist.Sql.Util (entityColumnNames, entityColumnCount, parseEntityValues, isIdField, hasCompositeKey)
import qualified Data.Set as Set
import Data.Set (Set)
import qualified Control.Monad.Trans.Reader as R
import qualified Control.Monad.Trans.State as S
import qualified Control.Monad.Trans.Writer as W
import qualified Data.ByteString as B
import qualified Data.Conduit as C
import qualified Data.Conduit.List as CL
import qualified Data.HashSet as HS
import qualified Data.Map.Strict as Map
import qualified Data.Text as T
import qualified Data.Text.Lazy as TL
import qualified Data.Text.Lazy.Builder as TLB
import Data.Typeable (Typeable)
import Text.Blaze.Html (Html)
import Database.Esqueleto.Internal.ExprParser (TableAccess(..), parseOnExpr)
-- | (Internal) Start a 'from' query with an entity. 'from'
-- does two kinds of magic using 'fromStart', 'fromJoin' and
-- 'fromFinish':
--
-- 1. The simple but tedious magic of allowing tuples to be
-- used.
--
-- 2. The more advanced magic of creating @JOIN@s. The
-- @JOIN@ is processed from right to left. The rightmost
-- entity of the @JOIN@ is created with 'fromStart'. Each
-- @JOIN@ step is then translated into a call to 'fromJoin'.
-- In the end, 'fromFinish' is called to materialize the
-- @JOIN@.
fromStart
:: ( PersistEntity a
, BackendCompatible SqlBackend (PersistEntityBackend a) )
=> SqlQuery (SqlExpr (PreprocessedFrom (SqlExpr (Entity a))))
fromStart = x
where
x = do
let ed = entityDef (getVal x)
ident <- newIdentFor (entityDB ed)
let ret = EEntity ident
f' = FromStart ident ed
return (EPreprocessedFrom ret f')
getVal :: SqlQuery (SqlExpr (PreprocessedFrom (SqlExpr (Entity a)))) -> Proxy a
getVal = const Proxy
-- | (Internal) Same as 'fromStart', but entity may be missing.
fromStartMaybe
:: ( PersistEntity a
, BackendCompatible SqlBackend (PersistEntityBackend a) )
=> SqlQuery (SqlExpr (PreprocessedFrom (SqlExpr (Maybe (Entity a)))))
fromStartMaybe = maybelize <$> fromStart
where
maybelize :: SqlExpr (PreprocessedFrom (SqlExpr (Entity a)))
-> SqlExpr (PreprocessedFrom (SqlExpr (Maybe (Entity a))))
maybelize (EPreprocessedFrom ret f') = EPreprocessedFrom (EMaybe ret) f'
-- | (Internal) Do a @JOIN@.
fromJoin
:: IsJoinKind join
=> SqlExpr (PreprocessedFrom a)
-> SqlExpr (PreprocessedFrom b)
-> SqlQuery (SqlExpr (PreprocessedFrom (join a b)))
fromJoin (EPreprocessedFrom lhsRet lhsFrom)
(EPreprocessedFrom rhsRet rhsFrom) = Q $ do
let ret = smartJoin lhsRet rhsRet
from' = FromJoin lhsFrom -- LHS
(reifyJoinKind ret) -- JOIN
rhsFrom -- RHS
Nothing -- ON
return (EPreprocessedFrom ret from')
-- | (Internal) Finish a @JOIN@.
fromFinish
:: SqlExpr (PreprocessedFrom a)
-> SqlQuery a
fromFinish (EPreprocessedFrom ret f') = Q $ do
W.tell mempty { sdFromClause = [f'] }
return ret
-- | @WHERE@ clause: restrict the query's result.
where_ :: SqlExpr (Value Bool) -> SqlQuery ()
where_ expr = Q $ W.tell mempty { sdWhereClause = Where expr }
-- | An @ON@ clause, useful to describe how two tables are related. Cross joins
-- and tuple-joins do not need an 'on' clause, but 'InnerJoin' and the various
-- outer joins do.
--
-- "Database.Esqueleto.Experimental" in version 4.0.0.0 of the library. The
-- @Experimental@ module has a dramatically improved means for introducing
-- tables and entities that provides more power and less potential for runtime
-- errors.
--
-- If you don't include an 'on' clause (or include too many!) then a runtime
-- exception will be thrown.
--
-- As an example, consider this simple join:
--
-- @
-- 'select' $
-- 'from' $ \\(foo `'InnerJoin`` bar) -> do
-- 'on' (foo '^.' FooId '==.' bar '^.' BarFooId)
-- ...
-- @
--
-- We need to specify the clause for joining the two columns together. If we had
-- this:
--
-- @
-- 'select' $
-- 'from' $ \\(foo `'CrossJoin`` bar) -> do
-- ...
-- @
--
-- Then we can safely omit the 'on' clause, because the cross join will make
-- pairs of all records possible.
--
-- You can do multiple 'on' clauses in a query. This query joins three tables,
-- and has two 'on' clauses:
--
-- @
-- 'select' $
-- 'from' $ \\(foo `'InnerJoin`` bar `'InnerJoin`` baz) -> do
-- 'on' (baz '^.' BazId '==.' bar '^.' BarBazId)
-- 'on' (foo '^.' FooId '==.' bar '^.' BarFooId)
-- ...
-- @
--
-- Old versions of esqueleto required that you provide the 'on' clauses in
-- reverse order. This restriction has been lifted - you can now provide 'on'
-- clauses in any order, and the SQL should work itself out. The above query is
-- now totally equivalent to this:
--
-- @
-- 'select' $
-- 'from' $ \\(foo `'InnerJoin`` bar `'InnerJoin`` baz) -> do
-- 'on' (foo '^.' FooId '==.' bar '^.' BarFooId)
-- 'on' (baz '^.' BazId '==.' bar '^.' BarBazId)
-- ...
-- @
on :: SqlExpr (Value Bool) -> SqlQuery ()
on expr = Q $ W.tell mempty { sdFromClause = [OnClause expr] }
-- | @GROUP BY@ clause. You can enclose multiple columns
-- in a tuple.
--
-- @
-- select $ 'from' \\(foo `'InnerJoin`` bar) -> do
-- 'on' (foo '^.' FooBarId '==.' bar '^.' BarId)
-- 'groupBy' (bar '^.' BarId, bar '^.' BarName)
-- return (bar '^.' BarId, bar '^.' BarName, countRows)
-- @
--
-- With groupBy you can sort by aggregate functions, like so
-- (we used @let@ to restrict the more general 'countRows' to
-- @SqlSqlExpr (Value Int)@ to avoid ambiguity---the second use of
-- 'countRows' has its type restricted by the @:: Int@ below):
--
-- @
-- r \<- select $ 'from' \\(foo `'InnerJoin`` bar) -> do
-- 'on' (foo '^.' FooBarId '==.' bar '^.' BarId)
-- 'groupBy' $ bar '^.' BarName
-- let countRows' = 'countRows'
-- 'orderBy' ['asc' countRows']
-- return (bar '^.' BarName, countRows')
-- forM_ r $ \\('Value' name, 'Value' count) -> do
-- print name
-- print (count :: Int)
-- @
--
-- === Need more columns?
--
-- The 'ToSomeValues' class is defined for 'SqlExpr' and tuples of 'SqlExpr's.
-- We only have definitions for up to 8 elements in a tuple right now, so it's
-- possible that you may need to have more than 8 elements.
--
-- For example, consider a query with a 'groupBy' call like this:
--
-- @
-- groupBy (e0, e1, e2, e3, e4, e5, e6, e7)
-- @
--
-- This is the biggest you can get with a single tuple. However, you can easily
-- nest the tuples to add more:
--
-- @
-- groupBy ((e0, e1, e2, e3, e4, e5, e6, e7), e8, e9)
-- @
groupBy :: (ToSomeValues a) => a -> SqlQuery ()
groupBy expr = Q $ W.tell mempty { sdGroupByClause = GroupBy $ toSomeValues expr }
-- | @ORDER BY@ clause. See also 'asc' and 'desc'.
--
-- Multiple calls to 'orderBy' get concatenated on the final
-- query, including 'distinctOnOrderBy'.
orderBy :: [SqlExpr OrderBy] -> SqlQuery ()
orderBy exprs = Q $ W.tell mempty { sdOrderByClause = exprs }
-- | Ascending order of this field or SqlExpression.
asc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy
asc = EOrderBy ASC
-- | Descending order of this field or SqlExpression.
desc :: PersistField a => SqlExpr (Value a) -> SqlExpr OrderBy
desc = EOrderBy DESC
-- | @LIMIT@. Limit the number of returned rows.
limit :: Int64 -> SqlQuery ()
limit n = Q $ W.tell mempty { sdLimitClause = Limit (Just n) Nothing }
-- | @OFFSET@. Usually used with 'limit'.
offset :: Int64 -> SqlQuery ()
offset n = Q $ W.tell mempty { sdLimitClause = Limit Nothing (Just n) }
-- | @DISTINCT@. Change the current @SELECT@ into @SELECT
-- DISTINCT@. For example:
--
-- @
-- select $ distinct $
-- 'from' \\foo -> do
-- ...
-- @
--
-- Note that this also has the same effect:
--
-- @
-- select $
-- 'from' \\foo -> do
-- distinct (return ())
-- ...
-- @
--
-- /Since: 2.2.4/
distinct :: SqlQuery a -> SqlQuery a
distinct act = Q (W.tell mempty { sdDistinctClause = DistinctStandard }) >> act
-- | @DISTINCT ON@. Change the current @SELECT@ into
-- @SELECT DISTINCT ON (SqlExpressions)@. For example:
--
-- @
-- select $
-- 'from' \\foo ->
-- 'distinctOn' ['don' (foo ^. FooName), 'don' (foo ^. FooState)] $ do
-- ...
-- @
--
-- You can also chain different calls to 'distinctOn'. The
-- above is equivalent to:
--
-- @
-- select $
-- 'from' \\foo ->
-- 'distinctOn' ['don' (foo ^. FooName)] $
-- 'distinctOn' ['don' (foo ^. FooState)] $ do
-- ...
-- @
--
-- Each call to 'distinctOn' adds more SqlExpressions. Calls to
-- 'distinctOn' override any calls to 'distinct'.
--
-- Note that PostgreSQL requires the SqlExpressions on @DISTINCT
-- ON@ to be the first ones to appear on a @ORDER BY@. This is
-- not managed automatically by esqueleto, keeping its spirit
-- of trying to be close to raw SQL.
--
-- Supported by PostgreSQL only.
--
-- /Since: 2.2.4/
distinctOn :: [SqlExpr DistinctOn] -> SqlQuery a -> SqlQuery a
distinctOn exprs act = Q (W.tell mempty { sdDistinctClause = DistinctOn exprs }) >> act
-- | Erase an SqlExpression's type so that it's suitable to
-- be used by 'distinctOn'.
--
-- /Since: 2.2.4/
don :: SqlExpr (Value a) -> SqlExpr DistinctOn
don = EDistinctOn
-- | A convenience function that calls both 'distinctOn' and
-- 'orderBy'. In other words,
--
-- @
-- 'distinctOnOrderBy' [asc foo, desc bar, desc quux] $ do
-- ...
-- @
--
-- is the same as:
--
-- @
-- 'distinctOn' [don foo, don bar, don quux] $ do
-- 'orderBy' [asc foo, desc bar, desc quux]
-- ...
-- @
--
-- /Since: 2.2.4/
distinctOnOrderBy :: [SqlExpr OrderBy] -> SqlQuery a -> SqlQuery a
distinctOnOrderBy exprs act =
distinctOn (toDistinctOn <$> exprs) $ do
orderBy exprs
act
where
toDistinctOn :: SqlExpr OrderBy -> SqlExpr DistinctOn
toDistinctOn (EOrderBy _ f) = EDistinctOn f
toDistinctOn EOrderRandom =
error "We can't select distinct by a random order!"
-- | @ORDER BY random()@ clause.
--
-- /Since: 1.3.10/
rand :: SqlExpr OrderBy
rand = EOrderRandom
-- | @HAVING@.
--
-- /Since: 1.2.2/
having :: SqlExpr (Value Bool) -> SqlQuery ()
having expr = Q $ W.tell mempty { sdHavingClause = Where expr }
-- | Add a locking clause to the query. Please read
-- 'LockingKind' documentation and your RDBMS manual.
--
-- If multiple calls to 'locking' are made on the same query,
-- the last one is used.
--
-- /Since: 2.2.7/
locking :: LockingKind -> SqlQuery ()
locking kind = Q $ W.tell mempty { sdLockingClause = Monoid.Last (Just kind) }
{-#
DEPRECATED
sub_select
"sub_select \n \
sub_select is an unsafe function to use. If used with a SqlQuery that \n \
returns 0 results, then it may return NULL despite not mentioning Maybe \n \
in the return type. If it returns more than 1 result, then it will throw a \n \
SQL error.\n\n Instead, consider using one of the following alternatives: \n \
- subSelect: attaches a LIMIT 1 and the Maybe return type, totally safe. \n \
- subSelectMaybe: Attaches a LIMIT 1, useful for a query that already \n \
has a Maybe in the return type. \n \
- subSelectCount: Performs a count of the query - this is always safe. \n \
- subSelectUnsafe: Performs no checks or guarantees. Safe to use with \n \
countRows and friends."
#-}
-- | Execute a subquery @SELECT@ in an SqlExpression. Returns a
-- simple value so should be used only when the @SELECT@ query
-- is guaranteed to return just one row.
--
-- Deprecated in 3.2.0.
sub_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a)
sub_select = sub SELECT
-- | Execute a subquery @SELECT@ in a 'SqlExpr'. The query passed to this
-- function will only return a single result - it has a @LIMIT 1@ passed in to
-- the query to make it safe, and the return type is 'Maybe' to indicate that
-- the subquery might result in 0 rows.
--
-- If you find yourself writing @'joinV' . 'subSelect'@, then consider using
-- 'subSelectMaybe'.
--
-- If you're performing a 'countRows', then you can use 'subSelectCount' which
-- is safe.
--
-- If you know that the subquery will always return exactly one row (eg
-- a foreign key constraint guarantees that you'll get exactly one row), then
-- consider 'subSelectUnsafe', along with a comment explaining why it is safe.
--
-- @since 3.2.0
subSelect
:: PersistField a
=> SqlQuery (SqlExpr (Value a))
-> SqlExpr (Value (Maybe a))
subSelect query = just (subSelectUnsafe (query <* limit 1))
-- | Execute a subquery @SELECT@ in a 'SqlExpr'. This function is a shorthand
-- for the common @'joinV' . 'subSelect'@ idiom, where you are calling
-- 'subSelect' on an expression that would be 'Maybe' already.
--
-- As an example, you would use this function when calling 'sum_' or 'max_',
-- which have 'Maybe' in the result type (for a 0 row query).
--
-- @since 3.2.0
subSelectMaybe
:: PersistField a
=> SqlQuery (SqlExpr (Value (Maybe a)))
-> SqlExpr (Value (Maybe a))
subSelectMaybe = joinV . subSelect
-- | Performs a @COUNT@ of the given query in a @subSelect@ manner. This is
-- always guaranteed to return a result value, and is completely safe.
--
-- @since 3.2.0
subSelectCount
:: (Num a, PersistField a)
=> SqlQuery ignored
-> SqlExpr (Value a)
subSelectCount query = do
subSelectUnsafe $ do
_ <- query
pure countRows
-- | Execute a subquery @SELECT@ in a 'SqlExpr' that returns a list. This is an
-- alias for 'subList_select' and is provided for symmetry with the other safe
-- subselect functions.
--
-- @since 3.2.0
subSelectList
:: PersistField a
=> SqlQuery (SqlExpr (Value a))
-> SqlExpr (ValueList a)
subSelectList = subList_select
-- | Performs a sub-select using the given foreign key on the entity. This is
-- useful to extract values that are known to be present by the database schema.
--
-- As an example, consider the following persistent definition:
--
-- @
-- User
-- profile ProfileId
--
-- Profile
-- name Text
-- @
--
-- The following query will return the name of the user.
--
-- @
-- getUserWithName =
-- 'select' $
-- 'from' $ \user ->
-- 'pure' (user, 'subSelectForeign' user UserProfile (^. ProfileName)
-- @
--
-- @since 3.2.0
subSelectForeign
::
( BackendCompatible SqlBackend (PersistEntityBackend val1)
, PersistEntity val1, PersistEntity val2, PersistField a
)
=> SqlExpr (Entity val2)
-- ^ An expression representing the table you have access to now.
-> EntityField val2 (Key val1)
-- ^ The foreign key field on the table.
-> (SqlExpr (Entity val1) -> SqlExpr (Value a))
-- ^ A function to extract a value from the foreign reference table.
-> SqlExpr (Value a)
subSelectForeign expr foreignKey k =
subSelectUnsafe $
from $ \table -> do
where_ $ expr ^. foreignKey ==. table ^. persistIdField
pure (k table)
-- | Execute a subquery @SELECT@ in a 'SqlExpr'. This function is unsafe,
-- because it can throw runtime exceptions in two cases:
--
-- 1. If the query passed has 0 result rows, then it will return a @NULL@ value.
-- The @persistent@ parsing operations will fail on an unexpected @NULL@.
-- 2. If the query passed returns more than one row, then the SQL engine will
-- fail with an error like "More than one row returned by a subquery used as
-- an expression".
--
-- This function is safe if you guarantee that exactly one row will be returned,
-- or if the result already has a 'Maybe' type for some reason.
--
-- For variants with the safety encoded already, see 'subSelect' and
-- 'subSelectMaybe'. For the most common safe use of this, see 'subSelectCount'.
--
-- @since 3.2.0
subSelectUnsafe :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a)
subSelectUnsafe = sub SELECT
-- | Project a field of an entity.
(^.)
:: forall typ val. (PersistEntity val, PersistField typ)
=> SqlExpr (Entity val)
-> EntityField val typ
-> SqlExpr (Value typ)
(EAliasedEntityReference source base) ^. field =
EValueReference source (\_ -> aliasedEntityColumnIdent base fieldDef)
where
fieldDef =
if isIdField field then
-- TODO what about composite natural keys in a join this will ignore them
head $ entityKeyFields ed
else
persistFieldDef field
ed = entityDef $ getEntityVal (Proxy :: Proxy (SqlExpr (Entity val)))
e ^. field
| isIdField field = idFieldValue
| otherwise = ERaw Never $ \info -> (dot info $ persistFieldDef field, [])
where
idFieldValue =
case entityKeyFields ed of
idField:[] ->
ERaw Never $ \info -> (dot info idField, [])
idFields ->
ECompositeKey $ \info -> dot info <$> idFields
ed = entityDef $ getEntityVal (Proxy :: Proxy (SqlExpr (Entity val)))
dot info fieldDef =
useIdent info sourceIdent <> "." <> fieldIdent
where
sourceIdent =
case e of
EEntity ident -> ident
EAliasedEntity baseI _ -> baseI
fieldIdent =
case e of
EEntity _ -> fromDBName info (fieldDB fieldDef)
EAliasedEntity baseI _ -> useIdent info $ aliasedEntityColumnIdent baseI fieldDef
-- | Project an SqlExpression that may be null, guarding against null cases.
withNonNull :: PersistField typ
=> SqlExpr (Value (Maybe typ))
-> (SqlExpr (Value typ) -> SqlQuery a)
-> SqlQuery a
withNonNull field f = do
where_ $ not_ $ isNothing field
f $ veryUnsafeCoerceSqlExprValue field
-- | Project a field of an entity that may be null.
(?.) :: (PersistEntity val, PersistField typ) =>
SqlExpr (Maybe (Entity val)) -> EntityField val typ -> SqlExpr (Value (Maybe typ))
EMaybe r ?. field = just (r ^. field)
-- | Lift a constant value from Haskell-land to the query.
val :: PersistField typ => typ -> SqlExpr (Value typ)
val v = ERaw Never $ const ("?", [toPersistValue v])
-- | @IS NULL@ comparison.
--
-- For @IS NOT NULL@, you can negate this with 'not_', as in @not_ (isNothing (person ^. PersonAge))@
--
-- Warning: Persistent and Esqueleto have different behavior for @!= Nothing@:
--
-- +----------------+----------------------------------+---------------+
-- | | Haskell | SQL |
-- +================+==================================+===============+
-- | __Persistent__ | @'Database.Persist.!=.' Nothing@ | @IS NOT NULL@ |
-- +----------------+----------------------------------+---------------+
-- | __Esqueleto__ | @'!=.' Nothing@ | @!= NULL@ |
-- +----------------+----------------------------------+---------------+
--
-- In SQL, @= NULL@ and @!= NULL@ return NULL instead of true or false. For this reason, you very likely do not want to use @'!=.' Nothing@ in Esqueleto.
-- You may find these @hlint@ rules helpful to enforce this:
--
-- > - error: {lhs: v ==. nothing, rhs: Database.Esqueleto.isNothing v, name: Use Esqueleto's isNothing}
-- > - error: {lhs: v ==. val Nothing, rhs: Database.Esqueleto.isNothing v, name: Use Esqueleto's isNothing}
-- > - error: {lhs: v !=. nothing, rhs: not_ (Database.Esqueleto.isNothing v), name: Use Esqueleto's not isNothing}
-- > - error: {lhs: v !=. val Nothing, rhs: not_ (Database.Esqueleto.isNothing v), name: Use Esqueleto's not isNothing}
isNothing :: PersistField typ => SqlExpr (Value (Maybe typ)) -> SqlExpr (Value Bool)
isNothing v =
case v of
ERaw p f -> isNullExpr $ first (parensM p) . f
EAliasedValue i _ -> isNullExpr $ aliasedValueIdentToRawSql i
EValueReference i i' -> isNullExpr $ valueReferenceToRawSql i i'
ECompositeKey f -> ERaw Parens $ flip (,) [] . (intersperseB " AND " . map (<> " IS NULL")) . f
where
isNullExpr :: (IdentInfo -> (TLB.Builder, [PersistValue])) -> SqlExpr (Value Bool)
isNullExpr g = ERaw Parens $ first ((<> " IS NULL")) . g
-- | Analogous to 'Just', promotes a value of type @typ@ into
-- one of type @Maybe typ@. It should hold that @'val' . Just
-- === just . 'val'@.
just :: SqlExpr (Value typ) -> SqlExpr (Value (Maybe typ))
just (ERaw p f) = ERaw p f
just (ECompositeKey f) = ECompositeKey f
just (EAliasedValue i v) = EAliasedValue i (just v)
just (EValueReference i i') = EValueReference i i'
-- | @NULL@ value.
nothing :: SqlExpr (Value (Maybe typ))
nothing = unsafeSqlValue "NULL"
-- | Join nested 'Maybe's in a 'Value' into one. This is useful when
-- calling aggregate functions on nullable fields.
joinV :: SqlExpr (Value (Maybe (Maybe typ))) -> SqlExpr (Value (Maybe typ))
joinV (ERaw p f) = ERaw p f
joinV (ECompositeKey f) = ECompositeKey f
joinV (EAliasedValue i v) = EAliasedValue i (joinV v)
joinV (EValueReference i i') = EValueReference i i'
countHelper :: Num a => TLB.Builder -> TLB.Builder -> SqlExpr (Value typ) -> SqlExpr (Value a)
countHelper open close v =
case v of
ERaw _ f -> countRawSql f
EAliasedValue i _ -> countRawSql $ aliasedValueIdentToRawSql i
EValueReference i i' -> countRawSql $ valueReferenceToRawSql i i'
ECompositeKey _ -> countRows
where
countRawSql :: (IdentInfo -> (TLB.Builder, [PersistValue])) -> SqlExpr (Value a)
countRawSql x = ERaw Never $ first (\b -> "COUNT" <> open <> parens b <> close) . x
-- | @COUNT(*)@ value.
countRows :: Num a => SqlExpr (Value a)
countRows = unsafeSqlValue "COUNT(*)"
-- | @COUNT@.
count :: Num a => SqlExpr (Value typ) -> SqlExpr (Value a)
count = countHelper "" ""
-- | @COUNT(DISTINCT x)@.
--
-- /Since: 2.4.1/
countDistinct :: Num a => SqlExpr (Value typ) -> SqlExpr (Value a)
countDistinct = countHelper "(DISTINCT " ")"
not_ :: SqlExpr (Value Bool) -> SqlExpr (Value Bool)
not_ v = ERaw Never (\info -> first ("NOT " <>) $ x info)
where
x info =
case v of
ERaw p f ->
let (b, vals) = f info
in (parensM p b, vals)
ECompositeKey _ -> throw (CompositeKeyErr NotError)
EAliasedValue i _ -> aliasedValueIdentToRawSql i info
EValueReference i i' -> valueReferenceToRawSql i i' info
(==.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
(==.) = unsafeSqlBinOpComposite " = " " AND "
(>=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
(>=.) = unsafeSqlBinOp " >= "
(>.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
(>.) = unsafeSqlBinOp " > "
(<=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
(<=.) = unsafeSqlBinOp " <= "
(<.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
(<.) = unsafeSqlBinOp " < "
(!=.) :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (Value typ) -> SqlExpr (Value Bool)
(!=.) = unsafeSqlBinOpComposite " != " " OR "
(&&.) :: SqlExpr (Value Bool) -> SqlExpr (Value Bool) -> SqlExpr (Value Bool)
(&&.) = unsafeSqlBinOp " AND "
(||.) :: SqlExpr (Value Bool) -> SqlExpr (Value Bool) -> SqlExpr (Value Bool)
(||.) = unsafeSqlBinOp " OR "
(+.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
(+.) = unsafeSqlBinOp " + "
(-.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
(-.) = unsafeSqlBinOp " - "
(/.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
(/.) = unsafeSqlBinOp " / "
(*.) :: PersistField a => SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value a)
(*.) = unsafeSqlBinOp " * "
-- | @BETWEEN@.
--
-- @since: 3.1.0
between :: PersistField a => SqlExpr (Value a) -> (SqlExpr (Value a), SqlExpr (Value a)) -> SqlExpr (Value Bool)
a `between` (b, c) = a >=. b &&. a <=. c
random_ :: (PersistField a, Num a) => SqlExpr (Value a)
random_ = unsafeSqlValue "RANDOM()"
round_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
round_ = unsafeSqlFunction "ROUND"
ceiling_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
ceiling_ = unsafeSqlFunction "CEILING"
floor_ :: (PersistField a, Num a, PersistField b, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
floor_ = unsafeSqlFunction "FLOOR"
sum_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b))
sum_ = unsafeSqlFunction "SUM"
min_ :: (PersistField a) => SqlExpr (Value a) -> SqlExpr (Value (Maybe a))
min_ = unsafeSqlFunction "MIN"
max_ :: (PersistField a) => SqlExpr (Value a) -> SqlExpr (Value (Maybe a))
max_ = unsafeSqlFunction "MAX"
avg_ :: (PersistField a, PersistField b) => SqlExpr (Value a) -> SqlExpr (Value (Maybe b))
avg_ = unsafeSqlFunction "AVG"
-- | Allow a number of one type to be used as one of another
-- type via an implicit cast. An explicit cast is not made,
-- this function changes only the types on the Haskell side.
--
-- /Caveat/: Trying to use @castNum@ from @Double@ to @Int@
-- will not result in an integer, the original fractional
-- number will still be used! Use 'round_', 'ceiling_' or
-- 'floor_' instead.
--
-- /Safety/: This operation is mostly safe due to the 'Num'
-- constraint between the types and the fact that RDBMSs
-- usually allow numbers of different types to be used
-- interchangeably. However, there may still be issues with
-- the query not being accepted by the RDBMS or @persistent@
-- not being able to parse it.
--
-- /Since: 2.2.9/
castNum :: (Num a, Num b) => SqlExpr (Value a) -> SqlExpr (Value b)
castNum = veryUnsafeCoerceSqlExprValue
-- | Same as 'castNum', but for nullable values.
--
-- /Since: 2.2.9/
castNumM :: (Num a, Num b) => SqlExpr (Value (Maybe a)) -> SqlExpr (Value (Maybe b))
castNumM = veryUnsafeCoerceSqlExprValue
-- | @COALESCE@ function. Evaluates the arguments in order and
-- returns the value of the first non-NULL SqlExpression, or NULL
-- (Nothing) otherwise. Some RDBMSs (such as SQLite) require
-- at least two arguments; please refer to the appropriate
-- documentation.
--
-- /Since: 1.4.3/
coalesce :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value (Maybe a))
coalesce = unsafeSqlFunctionParens "COALESCE"
-- | Like @coalesce@, but takes a non-nullable SqlExpression
-- placed at the end of the SqlExpression list, which guarantees
-- a non-NULL result.
--
-- /Since: 1.4.3/
coalesceDefault :: PersistField a => [SqlExpr (Value (Maybe a))] -> SqlExpr (Value a) -> SqlExpr (Value a)
coalesceDefault exprs = unsafeSqlFunctionParens "COALESCE" . (exprs ++) . return . just
-- | @LOWER@ function.
lower_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
lower_ = unsafeSqlFunction "LOWER"
-- | @UPPER@ function.
-- /Since: 3.3.0/
upper_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
upper_ = unsafeSqlFunction "UPPER"
-- | @TRIM@ function.
-- /Since: 3.3.0/
trim_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
trim_ = unsafeSqlFunction "TRIM"
-- | @RTRIM@ function.
-- /Since: 3.3.0/
rtrim_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
rtrim_ = unsafeSqlFunction "RTRIM"
-- | @LTRIM@ function.
-- /Since: 3.3.0/
ltrim_ :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s)
ltrim_ = unsafeSqlFunction "LTRIM"
-- | @LENGTH@ function.
-- /Since: 3.3.0/
length_ :: (SqlString s, Num a) => SqlExpr (Value s) -> SqlExpr (Value a)
length_ = unsafeSqlFunction "LENGTH"
-- | @LEFT@ function.
-- /Since: 3.3.0/
left_ :: (SqlString s, Num a) => (SqlExpr (Value s), SqlExpr (Value a)) -> SqlExpr (Value s)
left_ = unsafeSqlFunction "LEFT"
-- | @RIGHT@ function.
-- /Since: 3.3.0/
right_ :: (SqlString s, Num a) => (SqlExpr (Value s), SqlExpr (Value a)) -> SqlExpr (Value s)
right_ = unsafeSqlFunction "RIGHT"
-- | @LIKE@ operator.
like :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool)
like = unsafeSqlBinOp " LIKE "
-- | @ILIKE@ operator (case-insensitive @LIKE@).
--
-- Supported by PostgreSQL only.
--
-- /Since: 2.2.3/
ilike :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value Bool)
ilike = unsafeSqlBinOp " ILIKE "
-- | The string @'%'@. May be useful while using 'like' and
-- concatenation ('concat_' or '++.', depending on your
-- database). Note that you always have to type the parenthesis,
-- for example:
--
-- @
-- name `'like`` (%) ++. 'val' \"John\" ++. (%)
-- @
(%) :: SqlString s => SqlExpr (Value s)
(%) = unsafeSqlValue "'%'"
-- | The @CONCAT@ function with a variable number of
-- parameters. Supported by MySQL and PostgreSQL.
concat_ :: SqlString s => [SqlExpr (Value s)] -> SqlExpr (Value s)
concat_ = unsafeSqlFunction "CONCAT"
-- | The @||@ string concatenation operator (named after
-- Haskell's '++' in order to avoid naming clash with '||.').
-- Supported by SQLite and PostgreSQL.
(++.) :: SqlString s => SqlExpr (Value s) -> SqlExpr (Value s) -> SqlExpr (Value s)
(++.) = unsafeSqlBinOp " || "
-- | Cast a string type into 'Text'. This function
-- is very useful if you want to use @newtype@s, or if you want
-- to apply functions such as 'like' to strings of different
-- types.
--
-- /Safety:/ This is a slightly unsafe function, especially if
-- you have defined your own instances of 'SqlString'. Also,
-- since 'Maybe' is an instance of 'SqlString', it's possible
-- to turn a nullable value into a non-nullable one. Avoid
-- using this function if possible.
castString :: (SqlString s, SqlString r) => SqlExpr (Value s) -> SqlExpr (Value r)
castString = veryUnsafeCoerceSqlExprValue
-- | Execute a subquery @SELECT@ in an SqlExpression. Returns a
-- list of values.
subList_select :: PersistField a => SqlQuery (SqlExpr (Value a)) -> SqlExpr (ValueList a)
subList_select = EList . sub_select
-- | Lift a list of constant value from Haskell-land to the query.
valList :: PersistField typ => [typ] -> SqlExpr (ValueList typ)
valList [] = EEmptyList
valList vals = EList $ ERaw Parens $ const ( uncommas ("?" <$ vals)
, map toPersistValue vals )
-- | Same as 'just' but for 'ValueList'. Most of the time you
-- won't need it, though, because you can use 'just' from
-- inside 'subList_select' or 'Just' from inside 'valList'.
--
-- /Since: 2.2.12/
justList :: SqlExpr (ValueList typ) -> SqlExpr (ValueList (Maybe typ))
justList EEmptyList = EEmptyList
justList (EList v) = EList (just v)
-- | @IN@ operator. For example if you want to select all @Person@s by a list
-- of IDs:
--
-- @
-- SELECT *
-- FROM Person
-- WHERE Person.id IN (?)
-- @
--
-- In @esqueleto@, we may write the same query above as:
--
-- @
-- select $
-- 'from' $ \\person -> do
-- 'where_' $ person '^.' PersonId `'in_`` 'valList' personIds
-- return person
-- @
--
-- Where @personIds@ is of type @[Key Person]@.
in_ :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool)
v `in_` e = ifNotEmptyList e False $ unsafeSqlBinOp " IN " v (veryUnsafeCoerceSqlExprValueList e)
-- | @NOT IN@ operator.
notIn :: PersistField typ => SqlExpr (Value typ) -> SqlExpr (ValueList typ) -> SqlExpr (Value Bool)
v `notIn` e = ifNotEmptyList e True $ unsafeSqlBinOp " NOT IN " v (veryUnsafeCoerceSqlExprValueList e)
-- | @EXISTS@ operator. For example:
--
-- @
-- select $
-- 'from' $ \\person -> do
-- 'where_' $ 'exists' $
-- 'from' $ \\post -> do
-- 'where_' (post '^.' BlogPostAuthorId '==.' person '^.' PersonId)
-- return person
-- @
exists :: SqlQuery () -> SqlExpr (Value Bool)
exists = unsafeSqlFunction "EXISTS " . existsHelper
-- | @NOT EXISTS@ operator.
notExists :: SqlQuery () -> SqlExpr (Value Bool)
notExists = unsafeSqlFunction "NOT EXISTS " . existsHelper
-- | @SET@ clause used on @UPDATE@s. Note that while it's not
-- a type error to use this function on a @SELECT@, it will
-- most certainly result in a runtime error.
set :: PersistEntity val => SqlExpr (Entity val) -> [SqlExpr (Update val)] -> SqlQuery ()
set ent upds = Q $ W.tell mempty { sdSetClause = map apply upds }
where
apply (ESet f) = SetClause (f ent)
(=.) :: (PersistEntity val, PersistField typ) => EntityField val typ -> SqlExpr (Value typ) -> SqlExpr (Update val)
field =. expr = setAux field (const expr)
(+=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
field +=. expr = setAux field (\ent -> ent ^. field +. expr)
(-=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
field -=. expr = setAux field (\ent -> ent ^. field -. expr)
(*=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
field *=. expr = setAux field (\ent -> ent ^. field *. expr)
(/=.) :: (PersistEntity val, PersistField a) => EntityField val a -> SqlExpr (Value a) -> SqlExpr (Update val)
field /=. expr = setAux field (\ent -> ent ^. field /. expr)
-- | Apply a 'PersistField' constructor to @SqlExpr Value@ arguments.
(<#) :: (a -> b) -> SqlExpr (Value a) -> SqlExpr (Insertion b)
(<#) _ (ERaw _ f) = EInsert Proxy f
(<#) _ (ECompositeKey _) = throw (CompositeKeyErr ToInsertionError)
(<#) _ (EAliasedValue i _) = EInsert Proxy $ aliasedValueIdentToRawSql i
(<#) _ (EValueReference i i') = EInsert Proxy $ valueReferenceToRawSql i i'
-- | Apply extra @SqlExpr Value@ arguments to a 'PersistField' constructor
(<&>) :: SqlExpr (Insertion (a -> b)) -> SqlExpr (Value a) -> SqlExpr (Insertion b)
(EInsert _ f) <&> v = EInsert Proxy $ \x ->
let (fb, fv) = f x
(gb, gv) = g x
in (fb <> ", " <> gb, fv ++ gv)
where
g =
case v of
ERaw _ f' -> f'
EAliasedValue i _ -> aliasedValueIdentToRawSql i
EValueReference i i' -> valueReferenceToRawSql i i'
ECompositeKey _ -> throw (CompositeKeyErr CombineInsertionError)
-- | @CASE@ statement. For example:
--
-- @
-- select $
-- return $
-- 'case_'
-- [ 'when_'
-- ('exists' $
-- 'from' $ \\p -> do
-- 'where_' (p '^.' PersonName '==.' 'val' \"Mike\"))
-- 'then_'
-- ('sub_select' $
-- 'from' $ \\v -> do
-- let sub =
-- 'from' $ \\c -> do
-- 'where_' (c '^.' PersonName '==.' 'val' \"Mike\")
-- return (c '^.' PersonFavNum)
-- 'where_' (v '^.' PersonFavNum >. 'sub_select' sub)
-- return $ 'count' (v '^.' PersonName) +. 'val' (1 :: Int)) ]
-- ('else_' $ 'val' (-1))
-- @
--
-- This query is a bit complicated, but basically it checks if a person
-- named @\"Mike\"@ exists, and if that person does, run the subquery to find
-- out how many people have a ranking (by Fav Num) higher than @\"Mike\"@.
--
-- __NOTE:__ There are a few things to be aware about this statement.
--
-- * This only implements the full CASE statement, it does not
-- implement the \"simple\" CASE statement.
--
--
-- * At least one 'when_' and 'then_' is mandatory otherwise it will
-- emit an error.
--
--
-- * The 'else_' is also mandatory, unlike the SQL statement in which
-- if the @ELSE@ is omitted it will return a @NULL@. You can
-- reproduce this via 'nothing'.
--
-- /Since: 2.1.2/
case_ :: PersistField a => [(SqlExpr (Value Bool), SqlExpr (Value a))] -> SqlExpr (Value a) -> SqlExpr (Value a)
case_ = unsafeSqlCase
-- | Convert an entity's key into another entity's.
--
-- This function is to be used when you change an entity's @Id@ to be
-- that of another entity. For example:
--
-- @
-- Bar
-- barNum Int
-- Foo
-- bar BarId
-- fooNum Int
-- Primary bar
-- @
--
-- In this example, Bar is said to be the BaseEnt(ity), and Foo the child.
-- To model this in Esqueleto, declare:
--
-- @
-- instance ToBaseId Foo where
-- type BaseEnt Foo = Bar
-- toBaseIdWitness barId = FooKey barId
-- @
--
-- Now you're able to write queries such as:
--
-- @
-- 'select' $
-- 'from' $ \(bar `'InnerJoin`` foo) -> do
-- 'on' ('toBaseId' (foo '^.' FooId) '==.' bar '^.' BarId)
-- return (bar, foo)
-- @
--
-- Note: this function may be unsafe to use in conditions not like the
-- one of the example above.
--
-- /Since: 2.4.3/
toBaseId :: ToBaseId ent => SqlExpr (Value (Key ent)) -> SqlExpr (Value (Key (BaseEnt ent)))
toBaseId = veryUnsafeCoerceSqlExprValue
{-# DEPRECATED random_ "Since 2.6.0: `random_` is not uniform across all databases! Please use a specific one such as 'Database.Esqueleto.PostgreSQL.random_', 'Database.Esqueleto.MySQL.random_', or 'Database.Esqueleto.SQLite.random_'" #-}
{-# DEPRECATED rand "Since 2.6.0: `rand` ordering function is not uniform across all databases! To avoid accidental partiality it will be removed in the next major version." #-}
-- Fixity declarations
infixl 9 ^.
infixl 7 *., /.
infixl 6 +., -.
infixr 5 ++.
infix 4 ==., >=., >., <=., <., !=.
infixr 3 &&., =., +=., -=., *=., /=.
infixr 2 ||., `like`, `ilike`
infixl 2 `InnerJoin`, `CrossJoin`, `LeftOuterJoin`, `RightOuterJoin`, `FullOuterJoin`
-- | Syntax sugar for 'case_'.
--
-- /Since: 2.1.2/
when_ :: expr (Value Bool) -> () -> expr a -> (expr (Value Bool), expr a)
when_ cond _ expr = (cond, expr)
-- | Syntax sugar for 'case_'.
--
-- /Since: 2.1.2/
then_ :: ()
then_ = ()
-- | Syntax sugar for 'case_'.
--
-- /Since: 2.1.2/
else_ :: expr a -> expr a
else_ = id
-- | A single value (as opposed to a whole entity). You may use
-- @('^.')@ or @('?.')@ to get a 'Value' from an 'Entity'.
newtype Value a = Value { unValue :: a } deriving (Eq, Ord, Show, Typeable)
-- | /Since: 1.4.4/
instance Functor Value where
fmap f (Value a) = Value (f a)
instance Applicative Value where
(<*>) (Value f) (Value a) = Value (f a)
pure = Value
instance Monad Value where
(>>=) x f = valueJoin $ fmap f x
where valueJoin (Value v) = v
-- | A list of single values. There's a limited set of functions
-- able to work with this data type (such as 'subList_select',
-- 'valList', 'in_' and 'exists').
newtype ValueList a = ValueList a deriving (Eq, Ord, Show, Typeable)
-- | A wrapper type for for any @expr (Value a)@ for all a.
data SomeValue where
SomeValue :: SqlExpr (Value a) -> SomeValue
-- | A class of things that can be converted into a list of SomeValue. It has
-- instances for tuples and is the reason why 'groupBy' can take tuples, like
-- @'groupBy' (foo '^.' FooId, foo '^.' FooName, foo '^.' FooType)@.
class ToSomeValues a where
toSomeValues :: a -> [SomeValue]
instance ( ToSomeValues a
, ToSomeValues b
) => ToSomeValues (a, b) where
toSomeValues (a,b) = toSomeValues a ++ toSomeValues b
instance ( ToSomeValues a
, ToSomeValues b
, ToSomeValues c
) => ToSomeValues (a, b, c) where
toSomeValues (a,b,c) = toSomeValues a ++ toSomeValues b ++ toSomeValues c
instance ( ToSomeValues a
, ToSomeValues b
, ToSomeValues c
, ToSomeValues d
) => ToSomeValues (a, b, c, d) where
toSomeValues (a,b,c,d) = toSomeValues a ++ toSomeValues b ++ toSomeValues c ++
toSomeValues d
instance ( ToSomeValues a
, ToSomeValues b
, ToSomeValues c
, ToSomeValues d
, ToSomeValues e
) => ToSomeValues (a, b, c, d, e) where
toSomeValues (a,b,c,d,e) = toSomeValues a ++ toSomeValues b ++
toSomeValues c ++ toSomeValues d ++ toSomeValues e
instance ( ToSomeValues a
, ToSomeValues b
, ToSomeValues c
, ToSomeValues d
, ToSomeValues e
, ToSomeValues f
) => ToSomeValues (a, b, c, d, e, f) where
toSomeValues (a,b,c,d,e,f) = toSomeValues a ++ toSomeValues b ++
toSomeValues c ++ toSomeValues d ++ toSomeValues e ++ toSomeValues f
instance ( ToSomeValues a
, ToSomeValues b
, ToSomeValues c
, ToSomeValues d
, ToSomeValues e
, ToSomeValues f
, ToSomeValues g
) => ToSomeValues (a, b, c, d, e, f, g) where
toSomeValues (a,b,c,d,e,f,g) = toSomeValues a ++ toSomeValues b ++
toSomeValues c ++ toSomeValues d ++ toSomeValues e ++ toSomeValues f ++
toSomeValues g
instance ( ToSomeValues a
, ToSomeValues b
, ToSomeValues c
, ToSomeValues d
, ToSomeValues e
, ToSomeValues f
, ToSomeValues g
, ToSomeValues h
) => ToSomeValues (a, b, c, d, e, f, g, h) where
toSomeValues (a,b,c,d,e,f,g,h) = toSomeValues a ++ toSomeValues b ++
toSomeValues c ++ toSomeValues d ++ toSomeValues e ++ toSomeValues f ++
toSomeValues g ++ toSomeValues h
type family KnowResult a where
KnowResult (i -> o) = KnowResult o
KnowResult a = a
-- | A class for constructors or function which result type is known.
--
-- @since 3.1.3
class FinalResult a where
finalR :: a -> KnowResult a
instance FinalResult (Unique val) where
finalR = id
instance (FinalResult b) => FinalResult (a -> b) where
finalR f = finalR (f undefined)
-- | Convert a constructor for a 'Unique' key on a record to the 'UniqueDef' that defines it. You
-- can supply just the constructor itself, or a value of the type - the library is capable of figuring
-- it out from there.
--
-- @since 3.1.3
toUniqueDef :: forall a val. (KnowResult a ~ (Unique val), PersistEntity val,FinalResult a) =>
a -> UniqueDef
toUniqueDef uniqueConstructor = uniqueDef
where
proxy :: Proxy val
proxy = Proxy
unique :: Unique val
unique = finalR uniqueConstructor
-- there must be a better way to get the constrain name from a unique, make this not a list search
filterF = (==) (persistUniqueToFieldNames unique) . uniqueFields
uniqueDef = head . filter filterF . entityUniques . entityDef $ proxy
-- | Render updates to be use in a SET clause for a given sql backend.
--
-- @since 3.1.3
renderUpdates :: (BackendCompatible SqlBackend backend) =>
backend
-> [SqlExpr (Update val)]
-> (TLB.Builder, [PersistValue])
renderUpdates conn = uncommas' . concatMap renderUpdate
where
mk :: SqlExpr (Value ()) -> [(TLB.Builder, [PersistValue])]
mk (ERaw _ f) = [f info]
mk (ECompositeKey _) = throw (CompositeKeyErr MakeSetError) -- FIXME
mk (EAliasedValue i _) = [aliasedValueIdentToRawSql i info]
mk (EValueReference i i') = [valueReferenceToRawSql i i' info]
renderUpdate :: SqlExpr (Update val) -> [(TLB.Builder, [PersistValue])]
renderUpdate (ESet f) = mk (f undefined) -- second parameter of f is always unused
info = (projectBackend conn, initialIdentState)
-- | Data type that represents an @INNER JOIN@ (see 'LeftOuterJoin' for an example).
data InnerJoin a b = a `InnerJoin` b
-- | Data type that represents a @CROSS JOIN@ (see 'LeftOuterJoin' for an example).
data CrossJoin a b = a `CrossJoin` b
-- | Data type that represents a @LEFT OUTER JOIN@. For example,
--
-- @
-- select $
-- 'from' $ \\(person `'LeftOuterJoin`` pet) ->
-- ...
-- @
--
-- is translated into
--
-- @
-- SELECT ...
-- FROM Person LEFT OUTER JOIN Pet
-- ...
-- @
--
-- See also: 'from'.
data LeftOuterJoin a b = a `LeftOuterJoin` b
-- | Data type that represents a @RIGHT OUTER JOIN@ (see 'LeftOuterJoin' for an example).
data RightOuterJoin a b = a `RightOuterJoin` b
-- | Data type that represents a @FULL OUTER JOIN@ (see 'LeftOuterJoin' for an example).
data FullOuterJoin a b = a `FullOuterJoin` b
-- | (Internal) A kind of @JOIN@.
data JoinKind =
InnerJoinKind -- ^ @INNER JOIN@
| CrossJoinKind -- ^ @CROSS JOIN@
| LeftOuterJoinKind -- ^ @LEFT OUTER JOIN@
| RightOuterJoinKind -- ^ @RIGHT OUTER JOIN@
| FullOuterJoinKind -- ^ @FULL OUTER JOIN@
deriving (Eq, Show)
-- | (Internal) Functions that operate on types (that should be)
-- of kind 'JoinKind'.
class IsJoinKind join where
-- | (Internal) @smartJoin a b@ is a @JOIN@ of the correct kind.
smartJoin :: a -> b -> join a b
-- | (Internal) Reify a @JoinKind@ from a @JOIN@. This
-- function is non-strict.
reifyJoinKind :: join a b -> JoinKind
instance IsJoinKind InnerJoin where
smartJoin a b = a `InnerJoin` b
reifyJoinKind _ = InnerJoinKind
instance IsJoinKind CrossJoin where
smartJoin a b = a `CrossJoin` b
reifyJoinKind _ = CrossJoinKind
instance IsJoinKind LeftOuterJoin where
smartJoin a b = a `LeftOuterJoin` b
reifyJoinKind _ = LeftOuterJoinKind
instance IsJoinKind RightOuterJoin where
smartJoin a b = a `RightOuterJoin` b
reifyJoinKind _ = RightOuterJoinKind
instance IsJoinKind FullOuterJoin where
smartJoin a b = a `FullOuterJoin` b
reifyJoinKind _ = FullOuterJoinKind
-- | Exception thrown whenever 'on' is used to create an @ON@
-- clause but no matching @JOIN@ is found.
data OnClauseWithoutMatchingJoinException =
OnClauseWithoutMatchingJoinException String
deriving (Eq, Ord, Show, Typeable)
instance Exception OnClauseWithoutMatchingJoinException where
-- | (Internal) Phantom type used to process 'from' (see 'fromStart').
data PreprocessedFrom a
-- | Phantom type used by 'orderBy', 'asc' and 'desc'.
data OrderBy
-- | Phantom type used by 'distinctOn' and 'don'.
data DistinctOn
-- | Phantom type for a @SET@ operation on an entity of the given
-- type (see 'set' and '(=.)').
data Update typ
-- | Phantom type used by 'insertSelect'.
data Insertion a
-- | Different kinds of locking clauses supported by 'locking'.
--
-- Note that each RDBMS has different locking support. The
-- constructors of this datatype specify only the /syntax/ of the
-- locking mechanism, not its /semantics/. For example, even
-- though both MySQL and PostgreSQL support 'ForUpdate', there
-- are no guarantees that they will behave the same.
--
-- /Since: 2.2.7/
data LockingKind =
ForUpdate
-- ^ @FOR UPDATE@ syntax. Supported by MySQL, Oracle and
-- PostgreSQL.
--
-- /Since: 2.2.7/
| ForUpdateSkipLocked
-- ^ @FOR UPDATE SKIP LOCKED@ syntax. Supported by MySQL, Oracle and
-- PostgreSQL.
--
-- /Since: 2.2.7/
| ForShare
-- ^ @FOR SHARE@ syntax. Supported by PostgreSQL.
--
-- /Since: 2.2.7/
| LockInShareMode
-- ^ @LOCK IN SHARE MODE@ syntax. Supported by MySQL.
--
-- /Since: 2.2.7/
-- | Phantom class of data types that are treated as strings by the
-- RDBMS. It has no methods because it's only used to avoid type
-- errors such as trying to concatenate integers.
--
-- If you have a custom data type or @newtype@, feel free to make
-- it an instance of this class.
--
-- /Since: 2.4.0/
class PersistField a => SqlString a where
-- | /Since: 2.3.0/
instance (a ~ Char) => SqlString [a] where
-- | /Since: 2.3.0/
instance SqlString T.Text where
-- | /Since: 2.3.0/
instance SqlString TL.Text where
-- | /Since: 2.3.0/
instance SqlString B.ByteString where
-- | /Since: 2.3.0/
instance SqlString Html where
-- | /Since: 2.4.0/
instance SqlString a => SqlString (Maybe a) where
-- | Class that enables one to use 'toBaseId' to convert an entity's
-- key on a query into another (cf. 'toBaseId').
class ToBaseId ent where
-- | e.g. @type BaseEnt MyBase = MyChild@
type BaseEnt ent :: *
-- | Convert from the key of the BaseEnt(ity) to the key of the child entity.
-- This function is not actually called, but that it typechecks proves this operation is safe.
toBaseIdWitness :: Key (BaseEnt ent) -> Key ent
-- | @FROM@ clause: bring entities into scope.
--
-- Note that this function will be replaced by the one in
-- "Database.Esqueleto.Experimental" in version 4.0.0.0 of the library. The
-- @Experimental@ module has a dramatically improved means for introducing
-- tables and entities that provides more power and less potential for runtime
-- errors.
--
-- This function internally uses two type classes in order to
-- provide some flexibility of how you may call it. Internally
-- we refer to these type classes as the two different magics.
--
-- The innermost magic allows you to use @from@ with the
-- following types:
--
-- * @expr (Entity val)@, which brings a single entity into
-- scope.
--
-- * @expr (Maybe (Entity val))@, which brings a single entity
-- that may be @NULL@ into scope. Used for @OUTER JOIN@s.
--
-- * A @JOIN@ of any other two types allowed by the innermost
-- magic, where a @JOIN@ may be an 'InnerJoin', a 'CrossJoin', a
-- 'LeftOuterJoin', a 'RightOuterJoin', or a 'FullOuterJoin'.
-- The @JOINs@ have left fixity.
--
-- The outermost magic allows you to use @from@ on any tuples of
-- types supported by innermost magic (and also tuples of tuples,
-- and so on), up to 8-tuples.
--
-- Note that using @from@ for the same entity twice does work and
-- corresponds to a self-join. You don't even need to use two
-- different calls to @from@, you may use a @JOIN@ or a tuple.
--
-- The following are valid examples of uses of @from@ (the types
-- of the arguments of the lambda are inside square brackets):
--
-- @
-- 'from' $ \\person -> ...
-- 'from' $ \\(person, blogPost) -> ...
-- 'from' $ \\(p `'LeftOuterJoin`` mb) -> ...
-- 'from' $ \\(p1 `'InnerJoin`` f `'InnerJoin`` p2) -> ...
-- 'from' $ \\((p1 `'InnerJoin`` f) `'InnerJoin`` p2) -> ...
-- @
--
-- The types of the arguments to the lambdas above are,
-- respectively:
--
-- @
-- person
-- :: ( Esqueleto query expr backend
-- , PersistEntity Person
-- , PersistEntityBackend Person ~ backend
-- ) => expr (Entity Person)
-- (person, blogPost)
-- :: (...) => (expr (Entity Person), expr (Entity BlogPost))
-- (p `'LeftOuterJoin`` mb)
-- :: (...) => InnerJoin (expr (Entity Person)) (expr (Maybe (Entity BlogPost)))
-- (p1 `'InnerJoin`` f `'InnerJoin`` p2)
-- :: (...) => InnerJoin
-- (InnerJoin (expr (Entity Person))
-- (expr (Entity Follow)))
-- (expr (Entity Person))
-- (p1 `'InnerJoin`` (f `'InnerJoin`` p2)) ::
-- :: (...) => InnerJoin
-- (expr (Entity Person))
-- (InnerJoin (expr (Entity Follow))
-- (expr (Entity Person)))
-- @
--
-- Note that some backends may not support all kinds of @JOIN@s.
from :: From a => (a -> SqlQuery b) -> SqlQuery b
from = (from_ >>=)
-- | (Internal) Class that implements the tuple 'from' magic (see
-- 'fromStart').
class From a where
from_ :: SqlQuery a
instance ( FromPreprocess (SqlExpr (Entity val))
) => From (SqlExpr (Entity val)) where
from_ = fromPreprocess >>= fromFinish
instance ( FromPreprocess (SqlExpr (Maybe (Entity val)))
) => From (SqlExpr (Maybe (Entity val))) where
from_ = fromPreprocess >>= fromFinish
instance ( FromPreprocess (InnerJoin a b)
) => From (InnerJoin a b) where
from_ = fromPreprocess >>= fromFinish
instance ( FromPreprocess (CrossJoin a b)
) => From (CrossJoin a b) where
from_ = fromPreprocess >>= fromFinish
instance ( FromPreprocess (LeftOuterJoin a b)
) => From (LeftOuterJoin a b) where
from_ = fromPreprocess >>= fromFinish
instance ( FromPreprocess (RightOuterJoin a b)
) => From (RightOuterJoin a b) where
from_ = fromPreprocess >>= fromFinish
instance ( FromPreprocess (FullOuterJoin a b)
) => From (FullOuterJoin a b) where
from_ = fromPreprocess >>= fromFinish
instance ( From a
, From b
) => From (a, b) where
from_ = (,) <$> from_ <*> from_
instance ( From a
, From b
, From c
) => From (a, b, c) where
from_ = (,,) <$> from_ <*> from_ <*> from_
instance ( From a
, From b
, From c
, From d
) => From (a, b, c, d) where
from_ = (,,,) <$> from_ <*> from_ <*> from_ <*> from_
instance ( From a
, From b
, From c
, From d
, From e
) => From (a, b, c, d, e) where
from_ = (,,,,) <$> from_ <*> from_ <*> from_ <*> from_ <*> from_
instance ( From a
, From b
, From c
, From d
, From e
, From f
) => From (a, b, c, d, e, f) where
from_ = (,,,,,) <$> from_ <*> from_ <*> from_ <*> from_ <*> from_ <*> from_
instance ( From a
, From b
, From c
, From d
, From e
, From f
, From g
) => From (a, b, c, d, e, f, g) where
from_ = (,,,,,,) <$> from_ <*> from_ <*> from_ <*> from_ <*> from_ <*> from_ <*> from_
instance ( From a
, From b
, From c
, From d
, From e
, From f
, From g
, From h
) => From (a, b, c, d, e, f, g, h) where
from_ = (,,,,,,,) <$> from_ <*> from_ <*> from_ <*> from_ <*> from_ <*> from_ <*> from_ <*> from_
-- | (Internal) Class that implements the @JOIN@ 'from' magic
-- (see 'fromStart').
class FromPreprocess a where
fromPreprocess :: SqlQuery (SqlExpr (PreprocessedFrom a))
instance ( PersistEntity val
, BackendCompatible SqlBackend (PersistEntityBackend val)
) => FromPreprocess (SqlExpr (Entity val)) where
fromPreprocess = fromStart
instance ( PersistEntity val
, BackendCompatible SqlBackend (PersistEntityBackend val)
) => FromPreprocess (SqlExpr (Maybe (Entity val))) where
fromPreprocess = fromStartMaybe
instance ( FromPreprocess a
, FromPreprocess b
, IsJoinKind join
) => FromPreprocess (join a b) where
fromPreprocess = do
a <- fromPreprocess
b <- fromPreprocess
fromJoin a b
-- | Exception data type for @esqueleto@ internal errors
data EsqueletoError =
CompositeKeyErr CompositeKeyError
| AliasedValueErr UnexpectedValueError
| UnexpectedCaseErr UnexpectedCaseError
| SqlBinOpCompositeErr SqlBinOpCompositeError
deriving (Show)
instance Exception EsqueletoError
data UnexpectedValueError =
NotError
| ToInsertionError
| CombineInsertionError
| FoldHelpError
| SqlCaseError
| SqlCastAsError
| SqlFunctionError
| MakeOnClauseError
| MakeExcError
| MakeSetError
| MakeWhereError
| MakeHavingError
| FilterWhereAggError
| FilterWhereClauseError
deriving (Show)
type CompositeKeyError = UnexpectedValueError
data UnexpectedCaseError =
EmptySqlExprValueList
| MakeFromError
| UnsupportedSqlInsertIntoType
| InsertionFinalError
| NewIdentForError
| UnsafeSqlCaseError
| OperationNotSupported
| NotImplemented
deriving (Show)
data SqlBinOpCompositeError =
MismatchingLengthsError
| NullPlaceholdersError
| DeconstructionError
deriving (Show)
-- | SQL backend for @esqueleto@ using 'SqlPersistT'.
newtype SqlQuery a =
Q { unQ :: W.WriterT SideData (S.State IdentState) a }
instance Functor SqlQuery where
fmap f = Q . fmap f . unQ
instance Monad SqlQuery where
return = Q . return
m >>= f = Q (unQ m >>= unQ . f)
instance Applicative SqlQuery where
pure = return
(<*>) = ap
-- | Constraint synonym for @persistent@ entities whose backend
-- is 'SqlPersistT'.
type SqlEntity ent = (PersistEntity ent, PersistEntityBackend ent ~ SqlBackend)
----------------------------------------------------------------------
-- | Side data written by 'SqlQuery'.
data SideData = SideData { sdDistinctClause :: !DistinctClause
, sdFromClause :: ![FromClause]
, sdSetClause :: ![SetClause]
, sdWhereClause :: !WhereClause
, sdGroupByClause :: !GroupByClause
, sdHavingClause :: !HavingClause
, sdOrderByClause :: ![OrderByClause]
, sdLimitClause :: !LimitClause
, sdLockingClause :: !LockingClause
, sdCteClause :: ![CommonTableExpressionClause]
}
instance Semigroup SideData where
SideData d f s w g h o l k c <> SideData d' f' s' w' g' h' o' l' k' c' =
SideData (d <> d') (f <> f') (s <> s') (w <> w') (g <> g') (h <> h') (o <> o') (l <> l') (k <> k') (c <> c')
instance Monoid SideData where
mempty = SideData mempty mempty mempty mempty mempty mempty mempty mempty mempty mempty
mappend = (<>)
-- | The @DISTINCT@ "clause".
data DistinctClause =
DistinctAll -- ^ The default, everything.
| DistinctStandard -- ^ Only @DISTINCT@, SQL standard.
| DistinctOn [SqlExpr DistinctOn] -- ^ @DISTINCT ON@, PostgreSQL extension.
instance Semigroup DistinctClause where
DistinctOn a <> DistinctOn b = DistinctOn (a <> b)
DistinctOn a <> _ = DistinctOn a
DistinctStandard <> _ = DistinctStandard
DistinctAll <> b = b
instance Monoid DistinctClause where
mempty = DistinctAll
mappend = (<>)
-- | A part of a @FROM@ clause.
data FromClause =
FromStart Ident EntityDef
| FromJoin FromClause JoinKind FromClause (Maybe (SqlExpr (Value Bool)))
| OnClause (SqlExpr (Value Bool))
| FromQuery Ident (IdentInfo -> (TLB.Builder, [PersistValue])) SubQueryType
| FromIdent Ident
data CommonTableExpressionKind
= RecursiveCommonTableExpression
| NormalCommonTableExpression
deriving Eq
data CommonTableExpressionClause =
CommonTableExpressionClause CommonTableExpressionKind Ident (IdentInfo -> (TLB.Builder, [PersistValue]))
data SubQueryType
= NormalSubQuery
| LateralSubQuery
deriving Show
collectIdents :: FromClause -> Set Ident
collectIdents fc = case fc of
FromStart i _ -> Set.singleton i
FromJoin lhs _ rhs _ -> collectIdents lhs <> collectIdents rhs
OnClause _ -> mempty
FromQuery _ _ _ -> mempty
FromIdent _ -> mempty
instance Show FromClause where
show fc = case fc of
FromStart i _ ->
"(FromStart " <> show i <> ")"
FromJoin lhs jk rhs mexpr ->
mconcat
[ "(FromJoin "
, show lhs
, " "
, show jk
, " "
, case mexpr of
Nothing -> "(no on clause)"
Just expr -> "(" <> render' expr <> ")"
, " "
, show rhs
, ")"
]
OnClause expr ->
"(OnClause " <> render' expr <> ")"
FromQuery ident _ subQueryType ->
"(FromQuery " <> show ident <> " " <> show subQueryType <> ")"
FromIdent ident ->
"(FromIdent " <> show ident <> ")"
where
dummy = SqlBackend
{ connEscapeName = \(DBName x) -> x
}
render' = T.unpack . renderExpr dummy
-- | A part of a @SET@ clause.
newtype SetClause = SetClause (SqlExpr (Value ()))
-- | Collect 'OnClause's on 'FromJoin's. Returns the first
-- unmatched 'OnClause's data on error. Returns a list without
-- 'OnClauses' on success.
collectOnClauses
:: SqlBackend
-> [FromClause]
-> Either (SqlExpr (Value Bool)) [FromClause]
collectOnClauses sqlBackend = go Set.empty []
-- . (\fc -> Debug.trace ("From Clauses: " <> show fc) fc)
where
go is [] (f@(FromStart i _) : fs) =
fmap (f:) (go (Set.insert i is) [] fs) -- fast path
go idents acc (OnClause expr : fs) = do
(idents', a) <- findMatching idents acc expr
go idents' a fs
go idents acc (f:fs) =
go idents (f:acc) fs
go _ acc [] =
return $ reverse acc
findMatching
:: Set Ident
-> [FromClause]
-> SqlExpr (Value Bool)
-> Either (SqlExpr (Value Bool)) (Set Ident, [FromClause])
findMatching idents fromClauses expr =
-- Debug.trace ("From Clause: " <> show fromClauses) $
case fromClauses of
f : acc ->
let
idents' =
idents
<> Set.fromList (Maybe.catMaybes [findLeftmostIdent f, findRightmostIdent f])
in
case tryMatch idents' expr f of
Just (idents'', f') ->
return (idents'', f' : acc)
Nothing ->
fmap (f:) <$> findMatching idents' acc expr
[] ->
Left expr
findRightmostIdent (FromStart i _) = Just i
findRightmostIdent (FromJoin _ _ r _) = findRightmostIdent r
findRightmostIdent (OnClause {}) = Nothing
findRightmostIdent (FromQuery _ _ _) = Nothing
findRightmostIdent (FromIdent _) = Nothing
findLeftmostIdent (FromStart i _) = Just i
findLeftmostIdent (FromJoin l _ _ _) = findLeftmostIdent l
findLeftmostIdent (OnClause {}) = Nothing
findLeftmostIdent (FromQuery _ _ _) = Nothing
findLeftmostIdent (FromIdent _) = Nothing
tryMatch
:: Set Ident
-> SqlExpr (Value Bool)
-> FromClause
-> Maybe (Set Ident, FromClause)
tryMatch idents expr fromClause =
case fromClause of
FromJoin l k r onClause ->
matchTable <|> matchR <|> matchC <|> matchL <|> matchPartial -- right to left
where
matchR = fmap (\r' -> FromJoin l k r' onClause)
<$> tryMatch idents expr r
matchL = fmap (\l' -> FromJoin l' k r onClause)
<$> tryMatch idents expr l
matchPartial = do
--Debug.traceM $ "matchPartial"
--Debug.traceM $ "matchPartial: identsInOnClause: " <> show identsInOnClause
i1 <- findLeftmostIdent l
i2 <- findLeftmostIdent r
let leftIdents = collectIdents l
-- Debug.traceM $ "matchPartial: i1: " <> show i1
-- Debug.traceM $ "matchPartial: i2: " <> show i2
-- Debug.traceM $ "matchPartial: idents: " <> show idents
guard $
Set.isSubsetOf
identsInOnClause
(Set.fromList [i1, i2] <> leftIdents)
guard $ k /= CrossJoinKind
guard $ Maybe.isNothing onClause
pure (idents, FromJoin l k r (Just expr))
matchC =
case onClause of
Nothing
| "?" `T.isInfixOf` renderedExpr ->
return (idents, FromJoin l k r (Just expr))
| Set.null identsInOnClause ->
return (idents, FromJoin l k r (Just expr))
| otherwise ->
Nothing
Just _ ->
Nothing
matchTable = do
i1 <- findLeftmostIdent r
i2 <- findRightmostIdent l
guard $ Set.fromList [i1, i2] `Set.isSubsetOf` identsInOnClause
guard $ k /= CrossJoinKind
guard $ Maybe.isNothing onClause
pure (Set.fromList [i1, i2] <> idents, FromJoin l k r (Just expr))
_ ->
Nothing
where
identsInOnClause =
onExprToTableIdentifiers
renderedExpr =
renderExpr sqlBackend expr
onExprToTableIdentifiers =
Set.map (I . tableAccessTable)
. either error id
. parseOnExpr sqlBackend
$ renderedExpr
-- | A complete @WHERE@ clause.
data WhereClause = Where (SqlExpr (Value Bool))
| NoWhere
instance Semigroup WhereClause where
NoWhere <> w = w
w <> NoWhere = w
Where e1 <> Where e2 = Where (e1 &&. e2)
instance Monoid WhereClause where
mempty = NoWhere
mappend = (<>)
-- | A @GROUP BY@ clause.
newtype GroupByClause = GroupBy [SomeValue]
instance Semigroup GroupByClause where
GroupBy fs <> GroupBy fs' = GroupBy (fs <> fs')
instance Monoid GroupByClause where
mempty = GroupBy []
mappend = (<>)
-- | A @HAVING@ cause.
type HavingClause = WhereClause
-- | A @ORDER BY@ clause.
type OrderByClause = SqlExpr OrderBy
-- | A @LIMIT@ clause.
data LimitClause = Limit (Maybe Int64) (Maybe Int64)
deriving Eq
instance Semigroup LimitClause where
Limit l1 o1 <> Limit l2 o2 =
Limit (l2 `mplus` l1) (o2 `mplus` o1)
-- More than one 'limit' or 'offset' is issued, we want to
-- keep the latest one. That's why we use mplus with
-- "reversed" arguments.
instance Monoid LimitClause where
mempty = Limit mzero mzero
mappend = (<>)
-- | A locking clause.
type LockingClause = Monoid.Last LockingKind
----------------------------------------------------------------------
-- | Identifier used for table names.
newtype Ident = I T.Text
deriving (Eq, Ord, Show)
-- | List of identifiers already in use and supply of temporary
-- identifiers.
newtype IdentState = IdentState { inUse :: HS.HashSet T.Text }
initialIdentState :: IdentState
initialIdentState = IdentState mempty
-- | Create a fresh 'Ident'. If possible, use the given
-- 'DBName'.
newIdentFor :: DBName -> SqlQuery Ident
newIdentFor (DBName original) = Q $ lift $ findFree Nothing
where
findFree msuffix = do
let
withSuffix =
maybe id (\suffix -> (<> T.pack (show suffix))) msuffix original
isInUse <- S.gets (HS.member withSuffix . inUse)
if isInUse
then findFree (succ <$> (msuffix <|> Just (1 :: Int)))
else do
S.modify (\s -> s { inUse = HS.insert withSuffix (inUse s) })
pure (I withSuffix)
-- | Information needed to escape and use identifiers.
type IdentInfo = (SqlBackend, IdentState)
-- | Use an identifier.
useIdent :: IdentInfo -> Ident -> TLB.Builder
useIdent info (I ident) = fromDBName info $ DBName ident
-- | An expression on the SQL backend.
--
-- There are many comments describing the constructors of this
-- data type. However, Haddock doesn't like GADTs, so you'll have to read them by hitting \"Source\".
data SqlExpr a where
-- An entity, created by 'from' (cf. 'fromStart').
EEntity :: Ident -> SqlExpr (Entity val)
-- Base Table
EAliasedEntity :: Ident -> Ident -> SqlExpr (Entity val)
-- Source Base
EAliasedEntityReference :: Ident -> Ident -> SqlExpr (Entity val)
-- Just a tag stating that something is nullable.
EMaybe :: SqlExpr a -> SqlExpr (Maybe a)
-- Raw expression: states whether parenthesis are needed
-- around this expression, and takes information about the SQL
-- connection (mainly for escaping names) and returns both an
-- string ('TLB.Builder') and a list of values to be
-- interpolated by the SQL backend.
ERaw :: NeedParens -> (IdentInfo -> (TLB.Builder, [PersistValue])) -> SqlExpr (Value a)
-- A raw expression with an alias
EAliasedValue :: Ident -> SqlExpr (Value a) -> SqlExpr (Value a)
-- A reference to an aliased field in a table or subquery
EValueReference :: Ident -> (IdentInfo -> Ident) -> SqlExpr (Value a)
-- A composite key.
--
-- Persistent uses the same 'PersistList' constructor for both
-- fields which are (homogeneous) lists of values and the
-- (probably heterogeneous) values of a composite primary key.
--
-- We need to treat composite keys as fields. For example, we
-- have to support using ==., otherwise you wouldn't be able to
-- join. OTOH, lists of values should be treated exactly the
-- same as any other scalar value.
--
-- In particular, this is valid for persistent via rawSql for
-- an F field that is a list:
--
-- A.F in ? -- [PersistList [foo, bar]]
--
-- However, this is not for a composite key entity:
--
-- A.ID = ? -- [PersistList [foo, bar]]
--
-- The ID field doesn't exist on the DB for a composite key
-- table, it exists only on the Haskell side. Those variations
-- also don't work:
--
-- (A.KeyA, A.KeyB) = ? -- [PersistList [foo, bar]]
-- [A.KeyA, A.KeyB] = ? -- [PersistList [foo, bar]]
--
-- We have to generate:
--
-- A.KeyA = ? AND A.KeyB = ? -- [foo, bar]
--
-- Note that the PersistList had to be deconstructed into its
-- components.
--
-- In order to disambiguate behaviors, this constructor is used
-- /only/ to represent a composite field access. It does not
-- represent a 'PersistList', not even if the 'PersistList' is
-- used in the context of a composite key. That's because it's
-- impossible, e.g., for 'val' to disambiguate between these
-- uses.
ECompositeKey :: (IdentInfo -> [TLB.Builder]) -> SqlExpr (Value a)
-- 'EList' and 'EEmptyList' are used by list operators.
EList :: SqlExpr (Value a) -> SqlExpr (ValueList a)
EEmptyList :: SqlExpr (ValueList a)
-- A 'SqlExpr' accepted only by 'orderBy'.
EOrderBy :: OrderByType -> SqlExpr (Value a) -> SqlExpr OrderBy
EOrderRandom :: SqlExpr OrderBy
-- A 'SqlExpr' accepted only by 'distinctOn'.
EDistinctOn :: SqlExpr (Value a) -> SqlExpr DistinctOn
-- A 'SqlExpr' accepted only by 'set'.
ESet :: (SqlExpr (Entity val) -> SqlExpr (Value ())) -> SqlExpr (Update val)
-- An internal 'SqlExpr' used by the 'from' hack.
EPreprocessedFrom :: a -> FromClause -> SqlExpr (PreprocessedFrom a)
-- Used by 'insertSelect'.
EInsert :: Proxy a -> (IdentInfo -> (TLB.Builder, [PersistValue])) -> SqlExpr (Insertion a)
EInsertFinal :: PersistEntity a => SqlExpr (Insertion a) -> SqlExpr InsertFinal
-- | Phantom type used to mark a @INSERT INTO@ query.
data InsertFinal
data NeedParens = Parens | Never
deriving Eq
parensM :: NeedParens -> TLB.Builder -> TLB.Builder
parensM Never = id
parensM Parens = parens
data OrderByType = ASC | DESC
instance ToSomeValues (SqlExpr (Value a)) where
toSomeValues a = [SomeValue a]
fieldName :: (PersistEntity val, PersistField typ)
=> IdentInfo -> EntityField val typ -> TLB.Builder
fieldName info = fromDBName info . fieldDB . persistFieldDef
-- FIXME: Composite/non-id pKS not supported on set
setAux :: (PersistEntity val, PersistField typ)
=> EntityField val typ
-> (SqlExpr (Entity val) -> SqlExpr (Value typ))
-> SqlExpr (Update val)
setAux field mkVal = ESet $ \ent -> unsafeSqlBinOp " = " name (mkVal ent)
where name = ERaw Never $ \info -> (fieldName info field, mempty)
sub :: PersistField a => Mode -> SqlQuery (SqlExpr (Value a)) -> SqlExpr (Value a)
sub mode query = ERaw Parens $ \info -> toRawSql mode info query
fromDBName :: IdentInfo -> DBName -> TLB.Builder
fromDBName (conn, _) = TLB.fromText . connEscapeName conn
existsHelper :: SqlQuery () -> SqlExpr (Value Bool)
existsHelper = sub SELECT . (>> return true)
where
true :: SqlExpr (Value Bool)
true = val True
ifNotEmptyList :: SqlExpr (ValueList a) -> Bool -> SqlExpr (Value Bool) -> SqlExpr (Value Bool)
ifNotEmptyList EEmptyList b _ = val b
ifNotEmptyList (EList _) _ x = x
----------------------------------------------------------------------
-- | (Internal) Create a case statement.
--
-- Since: 2.1.1
unsafeSqlCase :: PersistField a => [(SqlExpr (Value Bool), SqlExpr (Value a))] -> SqlExpr (Value a) -> SqlExpr (Value a)
unsafeSqlCase when v = ERaw Never buildCase
where
buildCase :: IdentInfo -> (TLB.Builder, [PersistValue])
buildCase info =
let (elseText, elseVals) = valueToSql v info
(whenText, whenVals) = mapWhen when info
in ( "CASE" <> whenText <> " ELSE " <> elseText <> " END", whenVals <> elseVals)
mapWhen :: [(SqlExpr (Value Bool), SqlExpr (Value a))] -> IdentInfo -> (TLB.Builder, [PersistValue])
mapWhen [] _ = throw (UnexpectedCaseErr UnsafeSqlCaseError)
mapWhen when' info = foldl (foldHelp info) (mempty, mempty) when'
foldHelp :: IdentInfo -> (TLB.Builder, [PersistValue]) -> (SqlExpr (Value Bool), SqlExpr (Value a)) -> (TLB.Builder, [PersistValue])
foldHelp _ _ (ECompositeKey _, _) = throw (CompositeKeyErr FoldHelpError)
foldHelp _ _ (_, ECompositeKey _) = throw (CompositeKeyErr FoldHelpError)
foldHelp info (b0, vals0) (v1, v2) =
let (b1, vals1) = valueToSql v1 info
(b2, vals2) = valueToSql v2 info
in ( b0 <> " WHEN " <> b1 <> " THEN " <> b2, vals0 <> vals1 <> vals2 )
valueToSql :: SqlExpr (Value a) -> IdentInfo -> (TLB.Builder, [PersistValue])
valueToSql (ERaw p f) = (first (parensM p)) . f
valueToSql (ECompositeKey _) = throw (CompositeKeyErr SqlCaseError)
valueToSql (EAliasedValue i _) = aliasedValueIdentToRawSql i
valueToSql (EValueReference i i') = valueReferenceToRawSql i i'
-- | (Internal) Create a custom binary operator. You /should/
-- /not/ use this function directly since its type is very
-- general, you should always use it with an explicit type
-- signature. For example:
--
-- @
-- (==.) :: SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value Bool)
-- (==.) = unsafeSqlBinOp " = "
-- @
--
-- In the example above, we constraint the arguments to be of the
-- same type and constraint the result to be a boolean value.
unsafeSqlBinOp :: TLB.Builder -> SqlExpr (Value a) -> SqlExpr (Value b) -> SqlExpr (Value c)
unsafeSqlBinOp op (ERaw p1 f1) (ERaw p2 f2) = ERaw Parens f
where
f info = let (b1, vals1) = f1 info
(b2, vals2) = f2 info
in ( parensM p1 b1 <> op <> parensM p2 b2
, vals1 <> vals2 )
unsafeSqlBinOp op a b = unsafeSqlBinOp op (construct a) (construct b)
where construct :: SqlExpr (Value a) -> SqlExpr (Value a)
construct (ERaw p f) = ERaw (if p == Never then Parens else Never) $ \info ->
let (b1, vals) = f info
build ("?", [PersistList vals']) =
(uncommas $ replicate (length vals') "?", vals')
build expr = expr
in build (parensM p b1, vals)
construct (ECompositeKey f) =
ERaw Parens $ \info -> (uncommas $ f info, mempty)
construct (EAliasedValue i _) =
ERaw Never $ aliasedValueIdentToRawSql i
construct (EValueReference i i') =
ERaw Never $ valueReferenceToRawSql i i'
{-# INLINE unsafeSqlBinOp #-}
-- | Similar to 'unsafeSqlBinOp', but may also be applied to
-- composite keys. Uses the operator given as the second
-- argument whenever applied to composite keys.
--
-- Usage example:
--
-- @
-- (==.) :: SqlExpr (Value a) -> SqlExpr (Value a) -> SqlExpr (Value Bool)
-- (==.) = unsafeSqlBinOpComposite " = " " AND "
-- @
--
-- Persistent has a hack for implementing composite keys (see
-- 'ECompositeKey' doc for more details), so we're forced to use
-- a hack here as well. We deconstruct 'ERaw' values based on
-- two rules:
--
-- - If it is a single placeholder, then it's assumed to be
-- coming from a 'PersistList' and thus its components are
-- separated so that they may be applied to a composite key.
--
-- - If it is not a single placeholder, then it's assumed to be
-- a foreign (composite or not) key, so we enforce that it has
-- no placeholders and split it on the commas.
unsafeSqlBinOpComposite :: TLB.Builder -> TLB.Builder -> SqlExpr (Value a) -> SqlExpr (Value b) -> SqlExpr (Value c)
unsafeSqlBinOpComposite op sep a b
| isCompositeKey a || isCompositeKey b = ERaw Parens $ compose (listify a) (listify b)
| otherwise = unsafeSqlBinOp op a b
where
isCompositeKey :: SqlExpr (Value x) -> Bool
isCompositeKey (ECompositeKey _) = True
isCompositeKey _ = False
listify :: SqlExpr (Value x) -> IdentInfo -> ([TLB.Builder], [PersistValue])
listify (ECompositeKey f) = flip (,) [] . f
listify (ERaw _ f) = deconstruct . f
listify (EAliasedValue i _) = deconstruct . (aliasedValueIdentToRawSql i)
listify (EValueReference i i') = deconstruct . (valueReferenceToRawSql i i')
deconstruct :: (TLB.Builder, [PersistValue]) -> ([TLB.Builder], [PersistValue])
deconstruct ("?", [PersistList vals]) = (replicate (length vals) "?", vals)
deconstruct (b', []) = (TLB.fromLazyText <$> TL.splitOn "," (TLB.toLazyText b'), [])
deconstruct _ = throw (SqlBinOpCompositeErr DeconstructionError)
compose f1 f2 info
| not (null v1 || null v2) = throw (SqlBinOpCompositeErr NullPlaceholdersError)
| length b1 /= length b2 = throw (SqlBinOpCompositeErr MismatchingLengthsError)
| otherwise = (bc, vc)
where
(b1, v1) = f1 info
(b2, v2) = f2 info
bc = intersperseB sep [x <> op <> y | (x, y) <- zip b1 b2]
vc = v1 <> v2
-- | (Internal) A raw SQL value. The same warning from
-- 'unsafeSqlBinOp' applies to this function as well.
unsafeSqlValue :: TLB.Builder -> SqlExpr (Value a)
unsafeSqlValue v = ERaw Never $ const (v, mempty)
{-# INLINE unsafeSqlValue #-}
valueToFunctionArg :: IdentInfo -> SqlExpr (Value a) -> (TLB.Builder, [PersistValue])
valueToFunctionArg info v =
case v of
ERaw _ f -> f info
EAliasedValue i _ -> aliasedValueIdentToRawSql i info
EValueReference i i' -> valueReferenceToRawSql i i' info
ECompositeKey _ -> throw (CompositeKeyErr SqlFunctionError)
-- | (Internal) A raw SQL function. Once again, the same warning
-- from 'unsafeSqlBinOp' applies to this function as well.
unsafeSqlFunction :: UnsafeSqlFunctionArgument a =>
TLB.Builder -> a -> SqlExpr (Value b)
unsafeSqlFunction name arg =
ERaw Never $ \info ->
let (argsTLB, argsVals) =
uncommas' $ map (valueToFunctionArg info) $ toArgList arg
in (name <> parens argsTLB, argsVals)
-- | (Internal) An unsafe SQL function to extract a subfield from a compound
-- field, e.g. datetime. See 'unsafeSqlBinOp' for warnings.
--
-- Since: 1.3.6.
unsafeSqlExtractSubField :: UnsafeSqlFunctionArgument a =>
TLB.Builder -> a -> SqlExpr (Value b)
unsafeSqlExtractSubField subField arg =
ERaw Never $ \info ->
let (argsTLB, argsVals) =
uncommas' $ map (valueToFunctionArg info) $ toArgList arg
in ("EXTRACT" <> parens (subField <> " FROM " <> argsTLB), argsVals)
-- | (Internal) A raw SQL function. Preserves parentheses around arguments.
-- See 'unsafeSqlBinOp' for warnings.
unsafeSqlFunctionParens :: UnsafeSqlFunctionArgument a =>
TLB.Builder -> a -> SqlExpr (Value b)
unsafeSqlFunctionParens name arg =
ERaw Never $ \info ->
let
valueToFunctionArgParens v =
case v of
ERaw p f -> first (parensM p) (f info)
EAliasedValue i _ -> aliasedValueIdentToRawSql i info
EValueReference i i' -> valueReferenceToRawSql i i' info
ECompositeKey _ -> throw (CompositeKeyErr SqlFunctionError)
(argsTLB, argsVals) =
uncommas' $ map valueToFunctionArgParens $ toArgList arg
in (name <> parens argsTLB, argsVals)
-- | (Internal) An explicit SQL type cast using CAST(value as type).
-- See 'unsafeSqlBinOp' for warnings.
unsafeSqlCastAs :: T.Text -> SqlExpr (Value a) -> SqlExpr (Value b)
unsafeSqlCastAs t v = ERaw Never ((first (\value -> "CAST" <> parens (value <> " AS " <> TLB.fromText t))) . valueToText)
where
valueToText info =
case v of
(ERaw p f) ->
let (b, vals) = f info
in (parensM p b, vals)
EAliasedValue i _ -> aliasedValueIdentToRawSql i info
EValueReference i i' -> valueReferenceToRawSql i i' info
ECompositeKey _ -> throw (CompositeKeyErr SqlCastAsError)
-- | (Internal) This class allows 'unsafeSqlFunction' to work with different
-- numbers of arguments; specifically it allows providing arguments to a sql
-- function via an n-tuple of @SqlExpr (Value _)@ values, which are not all
-- necessarily required to be the same type. There are instances for up to
-- 10-tuples, but for sql functions which take more than 10 arguments, you can
-- also nest tuples, as e.g. @toArgList ((a,b),(c,d))@ is the same as
-- @toArgList (a,b,c,d)@.
class UnsafeSqlFunctionArgument a where
toArgList :: a -> [SqlExpr (Value ())]
-- | Useful for 0-argument functions, like @now@ in Postgresql.
--
-- @since 3.2.1
instance UnsafeSqlFunctionArgument () where
toArgList _ = []
instance (a ~ Value b) => UnsafeSqlFunctionArgument (SqlExpr a) where
toArgList = (:[]) . veryUnsafeCoerceSqlExprValue
instance UnsafeSqlFunctionArgument a =>
UnsafeSqlFunctionArgument [a] where
toArgList = concatMap toArgList
instance ( UnsafeSqlFunctionArgument a
, UnsafeSqlFunctionArgument b
) => UnsafeSqlFunctionArgument (a, b) where
toArgList (a, b) = toArgList a ++ toArgList b
instance ( UnsafeSqlFunctionArgument a
, UnsafeSqlFunctionArgument b
, UnsafeSqlFunctionArgument c
) => UnsafeSqlFunctionArgument (a, b, c) where
toArgList = toArgList . from3
instance ( UnsafeSqlFunctionArgument a
, UnsafeSqlFunctionArgument b
, UnsafeSqlFunctionArgument c
, UnsafeSqlFunctionArgument d
) => UnsafeSqlFunctionArgument (a, b, c, d) where
toArgList = toArgList . from4
-- | @since 3.2.3
instance ( UnsafeSqlFunctionArgument a
, UnsafeSqlFunctionArgument b
, UnsafeSqlFunctionArgument c
, UnsafeSqlFunctionArgument d
, UnsafeSqlFunctionArgument e
) => UnsafeSqlFunctionArgument (a, b, c, d, e) where
toArgList = toArgList . from5
-- | @since 3.2.3
instance ( UnsafeSqlFunctionArgument a
, UnsafeSqlFunctionArgument b
, UnsafeSqlFunctionArgument c
, UnsafeSqlFunctionArgument d
, UnsafeSqlFunctionArgument e
, UnsafeSqlFunctionArgument f
) => UnsafeSqlFunctionArgument (a, b, c, d, e, f) where
toArgList = toArgList . from6
-- | @since 3.2.3
instance ( UnsafeSqlFunctionArgument a
, UnsafeSqlFunctionArgument b
, UnsafeSqlFunctionArgument c
, UnsafeSqlFunctionArgument d
, UnsafeSqlFunctionArgument e
, UnsafeSqlFunctionArgument f
, UnsafeSqlFunctionArgument g
) => UnsafeSqlFunctionArgument (a, b, c, d, e, f, g) where
toArgList = toArgList . from7
-- | @since 3.2.3
instance ( UnsafeSqlFunctionArgument a
, UnsafeSqlFunctionArgument b
, UnsafeSqlFunctionArgument c
, UnsafeSqlFunctionArgument d
, UnsafeSqlFunctionArgument e
, UnsafeSqlFunctionArgument f
, UnsafeSqlFunctionArgument g
, UnsafeSqlFunctionArgument h
) => UnsafeSqlFunctionArgument (a, b, c, d, e, f, g, h) where
toArgList = toArgList . from8
-- | @since 3.2.3
instance ( UnsafeSqlFunctionArgument a
, UnsafeSqlFunctionArgument b
, UnsafeSqlFunctionArgument c
, UnsafeSqlFunctionArgument d
, UnsafeSqlFunctionArgument e
, UnsafeSqlFunctionArgument f
, UnsafeSqlFunctionArgument g
, UnsafeSqlFunctionArgument h
, UnsafeSqlFunctionArgument i
) => UnsafeSqlFunctionArgument (a, b, c, d, e, f, g, h, i) where
toArgList = toArgList . from9
-- | @since 3.2.3
instance ( UnsafeSqlFunctionArgument a
, UnsafeSqlFunctionArgument b
, UnsafeSqlFunctionArgument c
, UnsafeSqlFunctionArgument d
, UnsafeSqlFunctionArgument e
, UnsafeSqlFunctionArgument f
, UnsafeSqlFunctionArgument g
, UnsafeSqlFunctionArgument h
, UnsafeSqlFunctionArgument i
, UnsafeSqlFunctionArgument j
) => UnsafeSqlFunctionArgument (a, b, c, d, e, f, g, h, i, j) where
toArgList = toArgList . from10
-- | (Internal) Coerce a value's type from 'SqlExpr (Value a)' to
-- 'SqlExpr (Value b)'. You should /not/ use this function
-- unless you know what you're doing!
veryUnsafeCoerceSqlExprValue :: SqlExpr (Value a) -> SqlExpr (Value b)
veryUnsafeCoerceSqlExprValue (ERaw p f) = ERaw p f
veryUnsafeCoerceSqlExprValue (ECompositeKey f) = ECompositeKey f
veryUnsafeCoerceSqlExprValue (EAliasedValue i v) = EAliasedValue i (veryUnsafeCoerceSqlExprValue v)
veryUnsafeCoerceSqlExprValue (EValueReference i i') = EValueReference i i'
-- | (Internal) Coerce a value's type from 'SqlExpr (ValueList
-- a)' to 'SqlExpr (Value a)'. Does not work with empty lists.
veryUnsafeCoerceSqlExprValueList :: SqlExpr (ValueList a) -> SqlExpr (Value a)
veryUnsafeCoerceSqlExprValueList (EList v) = v
veryUnsafeCoerceSqlExprValueList EEmptyList = throw (UnexpectedCaseErr EmptySqlExprValueList)
----------------------------------------------------------------------
-- | (Internal) Execute an @esqueleto@ @SELECT@ 'SqlQuery' inside
-- @persistent@'s 'SqlPersistT' monad.
rawSelectSource :: ( SqlSelect a r
, MonadIO m1
, MonadIO m2
)
=> Mode
-> SqlQuery a
-> SqlReadT m1 (Acquire (C.ConduitT () r m2 ()))
rawSelectSource mode query =
do
conn <- projectBackend <$> R.ask
let _ = conn :: SqlBackend
res <- R.withReaderT (const conn) (run conn)
return $ (C..| massage) `fmap` res
where
run conn =
uncurry rawQueryRes $
first builderToText $
toRawSql mode (conn, initialIdentState) query
massage = do
mrow <- C.await
case process <$> mrow of
Just (Right r) -> C.yield r >> massage
Just (Left err) -> liftIO $ throwIO $ PersistMarshalError err
Nothing -> return ()
process = sqlSelectProcessRow
-- | Execute an @esqueleto@ @SELECT@ query inside @persistent@'s
-- 'SqlPersistT' monad and return a 'C.Source' of rows.
selectSource :: ( SqlSelect a r
, BackendCompatible SqlBackend backend
, IsPersistBackend backend
, PersistQueryRead backend
, PersistStoreRead backend, PersistUniqueRead backend
, MonadResource m )
=> SqlQuery a
-> C.ConduitT () r (R.ReaderT backend m) ()
selectSource query = do
res <- lift $ rawSelectSource SELECT query
(key, src) <- lift $ allocateAcquire res
src
lift $ release key
-- | Execute an @esqueleto@ @SELECT@ query inside @persistent@'s
-- 'SqlPersistT' monad and return a list of rows.
--
-- We've seen that 'from' has some magic about which kinds of
-- things you may bring into scope. This 'select' function also
-- has some magic for which kinds of things you may bring back to
-- Haskell-land by using @SqlQuery@'s @return@:
--
-- * You may return a @SqlExpr ('Entity' v)@ for an entity @v@
-- (i.e., like the @*@ in SQL), which is then returned to
-- Haskell-land as just @Entity v@.
--
-- * You may return a @SqlExpr (Maybe (Entity v))@ for an entity
-- @v@ that may be @NULL@, which is then returned to
-- Haskell-land as @Maybe (Entity v)@. Used for @OUTER JOIN@s.
--
-- * You may return a @SqlExpr ('Value' t)@ for a value @t@
-- (i.e., a single column), where @t@ is any instance of
-- 'PersistField', which is then returned to Haskell-land as
-- @Value t@. You may use @Value@ to return projections of an
-- @Entity@ (see @('^.')@ and @('?.')@) or to return any other
-- value calculated on the query (e.g., 'countRows' or
-- 'subSelect').
--
-- The @SqlSelect a r@ class has functional dependencies that
-- allow type information to flow both from @a@ to @r@ and
-- vice-versa. This means that you'll almost never have to give
-- any type signatures for @esqueleto@ queries. For example, the
-- query @'select' $ from $ \\p -> return p@ alone is ambiguous, but
-- in the context of
--
-- @
-- do ps <- 'select' $
-- 'from' $ \\p ->
-- return p
-- liftIO $ mapM_ (putStrLn . personName . entityVal) ps
-- @
--
-- we are able to infer from that single @personName . entityVal@
-- function composition that the @p@ inside the query is of type
-- @SqlExpr (Entity Person)@.
select :: ( SqlSelect a r
, MonadIO m
)
=> SqlQuery a -> SqlReadT m [r]
select query = do
res <- rawSelectSource SELECT query
conn <- R.ask
liftIO $ with res $ flip R.runReaderT conn . runSource
-- | (Internal) Run a 'C.Source' of rows.
runSource :: Monad m =>
C.ConduitT () r (R.ReaderT backend m) ()
-> R.ReaderT backend m [r]
runSource src = C.runConduit $ src C..| CL.consume
----------------------------------------------------------------------
-- | (Internal) Execute an @esqueleto@ statement inside
-- @persistent@'s 'SqlPersistT' monad.
rawEsqueleto :: ( MonadIO m, SqlSelect a r, BackendCompatible SqlBackend backend)
=> Mode
-> SqlQuery a
-> R.ReaderT backend m Int64
rawEsqueleto mode query = do
conn <- R.ask
uncurry rawExecuteCount $
first builderToText $
toRawSql mode (conn, initialIdentState) query
-- | Execute an @esqueleto@ @DELETE@ query inside @persistent@'s
-- 'SqlPersistT' monad. Note that currently there are no type
-- checks for statements that should not appear on a @DELETE@
-- query.
--
-- Example of usage:
--
-- @
-- 'delete' $
-- 'from' $ \\appointment ->
-- 'where_' (appointment '^.' AppointmentDate '<.' 'val' now)
-- @
--
-- Unlike 'select', there is a useful way of using 'delete' that
-- will lead to type ambiguities. If you want to delete all rows
-- (i.e., no 'where_' clause), you'll have to use a type signature:
--
-- @
-- 'delete' $
-- 'from' $ \\(appointment :: 'SqlExpr' ('Entity' Appointment)) ->
-- return ()
-- @
delete :: ( MonadIO m )
=> SqlQuery ()
-> SqlWriteT m ()
delete = void . deleteCount
-- | Same as 'delete', but returns the number of rows affected.
deleteCount :: ( MonadIO m )
=> SqlQuery ()
-> SqlWriteT m Int64
deleteCount = rawEsqueleto DELETE
-- | Execute an @esqueleto@ @UPDATE@ query inside @persistent@'s
-- 'SqlPersistT' monad. Note that currently there are no type
-- checks for statements that should not appear on a @UPDATE@
-- query.
--
-- Example of usage:
--
-- @
-- 'update' $ \\p -> do
-- 'set' p [ PersonAge '=.' 'just' ('val' thisYear) -. p '^.' PersonBorn ]
-- 'where_' $ isNothing (p '^.' PersonAge)
-- @
update
::
( MonadIO m, PersistEntity val
, BackendCompatible SqlBackend (PersistEntityBackend val)
)
=> (SqlExpr (Entity val) -> SqlQuery ())
-> SqlWriteT m ()
update = void . updateCount
-- | Same as 'update', but returns the number of rows affected.
updateCount
::
( MonadIO m, PersistEntity val
, BackendCompatible SqlBackend (PersistEntityBackend val)
)
=> (SqlExpr (Entity val) -> SqlQuery ())
-> SqlWriteT m Int64
updateCount = rawEsqueleto UPDATE . from
----------------------------------------------------------------------
builderToText :: TLB.Builder -> T.Text
builderToText = TL.toStrict . TLB.toLazyTextWith defaultChunkSize
where
defaultChunkSize = 1024 - 32
-- | (Internal) Pretty prints a 'SqlQuery' into a SQL query.
--
-- Note: if you're curious about the SQL query being generated by
-- @esqueleto@, instead of manually using this function (which is
-- possible but tedious), see the 'renderQueryToText' function (along with
-- 'renderQuerySelect', 'renderQueryUpdate', etc).
toRawSql
:: (SqlSelect a r, BackendCompatible SqlBackend backend)
=> Mode -> (backend, IdentState) -> SqlQuery a -> (TLB.Builder, [PersistValue])
toRawSql mode (conn, firstIdentState) query =
let ((ret, sd), finalIdentState) =
flip S.runState firstIdentState $
W.runWriterT $
unQ query
SideData distinctClause
fromClauses
setClauses
whereClauses
groupByClause
havingClause
orderByClauses
limitClause
lockingClause
cteClause = sd
-- Pass the finalIdentState (containing all identifiers
-- that were used) to the subsequent calls. This ensures
-- that no name clashes will occur on subqueries that may
-- appear on the expressions below.
info = (projectBackend conn, finalIdentState)
in mconcat
[ makeCte info cteClause
, makeInsertInto info mode ret
, makeSelect info mode distinctClause ret
, makeFrom info mode fromClauses
, makeSet info setClauses
, makeWhere info whereClauses
, makeGroupBy info groupByClause
, makeHaving info havingClause
, makeOrderBy info orderByClauses
, makeLimit info limitClause orderByClauses
, makeLocking lockingClause
]
-- | Renders a 'SqlQuery' into a 'Text' value along with the list of
-- 'PersistValue's that would be supplied to the database for @?@ placeholders.
--
-- You must ensure that the 'Mode' you pass to this function corresponds with
-- the actual 'SqlQuery'. If you pass a query that uses incompatible features
-- (like an @INSERT@ statement with a @SELECT@ mode) then you'll get a weird
-- result.
--
-- @since 3.1.1
renderQueryToText
:: (SqlSelect a r, BackendCompatible SqlBackend backend, Monad m)
=> Mode
-- ^ Whether to render as an 'SELECT', 'DELETE', etc.
-> SqlQuery a
-- ^ The SQL query you want to render.
-> R.ReaderT backend m (T.Text, [PersistValue])
renderQueryToText mode query = do
backend <- R.ask
let (builder, pvals) = toRawSql mode (backend, initialIdentState) query
pure (builderToText builder, pvals)
-- | Renders a 'SqlQuery' into a 'Text' value along with the list of
-- 'PersistValue's that would be supplied to the database for @?@ placeholders.
--
-- @since 3.1.1
renderQuerySelect
:: (SqlSelect a r, BackendCompatible SqlBackend backend, Monad m)
=> SqlQuery a
-- ^ The SQL query you want to render.
-> R.ReaderT backend m (T.Text, [PersistValue])
renderQuerySelect = renderQueryToText SELECT
-- | Renders a 'SqlQuery' into a 'Text' value along with the list of
-- 'PersistValue's that would be supplied to the database for @?@ placeholders.
--
-- @since 3.1.1
renderQueryDelete
:: (SqlSelect a r, BackendCompatible SqlBackend backend, Monad m)
=> SqlQuery a
-- ^ The SQL query you want to render.
-> R.ReaderT backend m (T.Text, [PersistValue])
renderQueryDelete = renderQueryToText DELETE
-- | Renders a 'SqlQuery' into a 'Text' value along with the list of
-- 'PersistValue's that would be supplied to the database for @?@ placeholders.
--
-- @since 3.1.1
renderQueryUpdate
:: (SqlSelect a r, BackendCompatible SqlBackend backend, Monad m)
=> SqlQuery a
-- ^ The SQL query you want to render.
-> R.ReaderT backend m (T.Text, [PersistValue])
renderQueryUpdate = renderQueryToText UPDATE
-- | Renders a 'SqlQuery' into a 'Text' value along with the list of
-- 'PersistValue's that would be supplied to the database for @?@ placeholders.
--
-- @since 3.1.1
renderQueryInsertInto
:: (SqlSelect a r, BackendCompatible SqlBackend backend, Monad m)
=> SqlQuery a
-- ^ The SQL query you want to render.
-> R.ReaderT backend m (T.Text, [PersistValue])
renderQueryInsertInto = renderQueryToText INSERT_INTO
-- | (Internal) Mode of query being converted by 'toRawSql'.
data Mode =
SELECT
| DELETE
| UPDATE
| INSERT_INTO
uncommas :: [TLB.Builder] -> TLB.Builder
uncommas = intersperseB ", "
intersperseB :: TLB.Builder -> [TLB.Builder] -> TLB.Builder
intersperseB a = mconcat . intersperse a . filter (/= mempty)
uncommas' :: Monoid a => [(TLB.Builder, a)] -> (TLB.Builder, a)
uncommas' = (uncommas *** mconcat) . unzip
makeCte :: IdentInfo -> [CommonTableExpressionClause] -> (TLB.Builder, [PersistValue])
makeCte info cteClauses =
let
withCteText
| hasRecursive = "WITH RECURSIVE "
| otherwise = "WITH "
where
hasRecursive =
any (== RecursiveCommonTableExpression) $
fmap (\(CommonTableExpressionClause cteKind _ _) -> cteKind) cteClauses
cteClauseToText (CommonTableExpressionClause _ cteIdent cteFn) =
first (\tlb ->
useIdent info cteIdent <> " AS " <> parens tlb
) $ cteFn info
cteBody =
mconcat $
intersperse (",\n", mempty) $
fmap cteClauseToText cteClauses
in
if length cteClauses == 0 then
mempty
else
first (\tlb -> withCteText <> tlb <> "\n") cteBody
makeInsertInto :: SqlSelect a r => IdentInfo -> Mode -> a -> (TLB.Builder, [PersistValue])
makeInsertInto info INSERT_INTO ret = sqlInsertInto info ret
makeInsertInto _ _ _ = mempty
makeSelect :: SqlSelect a r => IdentInfo -> Mode -> DistinctClause -> a -> (TLB.Builder, [PersistValue])
makeSelect info mode_ distinctClause ret = process mode_
where
process mode =
case mode of
SELECT -> withCols selectKind
DELETE -> plain "DELETE "
UPDATE -> plain "UPDATE "
INSERT_INTO -> process SELECT
selectKind =
case distinctClause of
DistinctAll -> ("SELECT ", [])
DistinctStandard -> ("SELECT DISTINCT ", [])
DistinctOn exprs -> first (("SELECT DISTINCT ON (" <>) . (<> ") ")) $
uncommas' (processExpr <$> exprs)
where processExpr (EDistinctOn f) = materializeExpr info f
withCols v = v <> sqlSelectCols info ret
plain v = (v, [])
makeFrom
:: IdentInfo
-> Mode
-> [FromClause]
-> (TLB.Builder, [PersistValue])
makeFrom _ _ [] = mempty
makeFrom info mode fs = ret
where
ret = case collectOnClauses (fst info) fs of
Left expr -> throw $ mkExc expr
Right fs' -> keyword $ uncommas' (map (mk Never) fs')
keyword = case mode of
UPDATE -> id
_ -> first ("\nFROM " <>)
mk _ (FromStart i def) = base i def
mk paren (FromJoin lhs kind rhs monClause) =
first (parensM paren) $
mconcat [ mk Never lhs
, (fromKind kind, mempty)
, mk Parens rhs
, maybe mempty makeOnClause monClause
]
mk _ (OnClause _) = throw (UnexpectedCaseErr MakeFromError)
mk _ (FromQuery ident f subqueryType) =
let (queryText, queryVals) = f info
lateralKeyword =
case subqueryType of
NormalSubQuery -> ""
LateralSubQuery -> "LATERAL "
in (lateralKeyword <> (parens queryText) <> " AS " <> useIdent info ident, queryVals)
mk _ (FromIdent ident) =
(useIdent info ident, mempty)
base ident@(I identText) def =
let db@(DBName dbText) = entityDB def
in ( if dbText == identText
then fromDBName info db
else fromDBName info db <> (" AS " <> useIdent info ident)
, mempty )
fromKind InnerJoinKind = " INNER JOIN "
fromKind CrossJoinKind = " CROSS JOIN "
fromKind LeftOuterJoinKind = " LEFT OUTER JOIN "
fromKind RightOuterJoinKind = " RIGHT OUTER JOIN "
fromKind FullOuterJoinKind = " FULL OUTER JOIN "
makeOnClause (ERaw _ f) = first (" ON " <>) (f info)
makeOnClause (ECompositeKey _) = throw (CompositeKeyErr MakeOnClauseError)
makeOnClause (EAliasedValue _ _) = throw (AliasedValueErr MakeOnClauseError)
makeOnClause (EValueReference _ _) = throw (AliasedValueErr MakeOnClauseError)
mkExc :: SqlExpr (Value Bool) -> OnClauseWithoutMatchingJoinException
mkExc (ERaw _ f) =
OnClauseWithoutMatchingJoinException $
TL.unpack $ TLB.toLazyText $ fst (f info)
mkExc (ECompositeKey _) = throw (CompositeKeyErr MakeExcError)
mkExc (EAliasedValue _ _) = throw (AliasedValueErr MakeExcError)
mkExc (EValueReference _ _) = throw (AliasedValueErr MakeExcError)
makeSet :: IdentInfo -> [SetClause] -> (TLB.Builder, [PersistValue])
makeSet _ [] = mempty
makeSet info os = first ("\nSET " <>) . uncommas' $ concatMap mk os
where
mk (SetClause (ERaw _ f)) = [f info]
mk (SetClause (ECompositeKey _)) = throw (CompositeKeyErr MakeSetError) -- FIXME
mk (SetClause (EAliasedValue i _)) = [aliasedValueIdentToRawSql i info]
mk (SetClause (EValueReference i i')) = [valueReferenceToRawSql i i' info]
makeWhere :: IdentInfo -> WhereClause -> (TLB.Builder, [PersistValue])
makeWhere _ NoWhere = mempty
makeWhere info (Where v) = first ("\nWHERE " <>) $ x info
where
x =
case v of
ERaw _ f -> f
EAliasedValue i _ -> aliasedValueIdentToRawSql i
EValueReference i i' -> valueReferenceToRawSql i i'
ECompositeKey _ -> throw (CompositeKeyErr MakeWhereError)
makeGroupBy :: IdentInfo -> GroupByClause -> (TLB.Builder, [PersistValue])
makeGroupBy _ (GroupBy []) = (mempty, [])
makeGroupBy info (GroupBy fields) = first ("\nGROUP BY " <>) build
where
build :: (TLB.Builder, [PersistValue])
build = uncommas' $ map match fields
match :: SomeValue -> (TLB.Builder, [PersistValue])
match (SomeValue (ERaw _ f)) = f info
match (SomeValue (ECompositeKey f)) = (mconcat $ f info, mempty)
match (SomeValue (EAliasedValue i _)) = aliasedValueIdentToRawSql i info
match (SomeValue (EValueReference i i')) = valueReferenceToRawSql i i' info
makeHaving :: IdentInfo -> WhereClause -> (TLB.Builder, [PersistValue])
makeHaving _ NoWhere = mempty
makeHaving info (Where v) = first ("\nHAVING " <>) $ x info
where
x =
case v of
ERaw _ f -> f
EAliasedValue i _ -> aliasedValueIdentToRawSql i
EValueReference i i' -> valueReferenceToRawSql i i'
ECompositeKey _ -> throw (CompositeKeyErr MakeHavingError)
-- makeHaving, makeWhere and makeOrderBy
makeOrderByNoNewline ::
IdentInfo -> [OrderByClause] -> (TLB.Builder, [PersistValue])
makeOrderByNoNewline _ [] = mempty
makeOrderByNoNewline info os = first ("ORDER BY " <>) . uncommas' $ concatMap mk os
where
mk :: OrderByClause -> [(TLB.Builder, [PersistValue])]
mk (EOrderBy t (ECompositeKey f)) =
let fs = f info
vals = repeat []
in zip (map (<> orderByType t) fs) vals
mk (EOrderBy t v) =
let x = case v of
ERaw p f -> (first (parensM p)) . f
EAliasedValue i _ -> aliasedValueIdentToRawSql i
EValueReference i i' -> valueReferenceToRawSql i i'
ECompositeKey _ -> undefined -- defined above
in [ first (<> orderByType t) $ x info ]
mk EOrderRandom = [first (<> "RANDOM()") mempty]
orderByType ASC = " ASC"
orderByType DESC = " DESC"
makeOrderBy :: IdentInfo -> [OrderByClause] -> (TLB.Builder, [PersistValue])
makeOrderBy _ [] = mempty
makeOrderBy info is =
let (tlb, vals) = makeOrderByNoNewline info is
in ("\n" <> tlb, vals)
{-# DEPRECATED EOrderRandom "Since 2.6.0: `rand` ordering function is not uniform across all databases! To avoid accidental partiality it will be removed in the next major version." #-}
makeLimit :: IdentInfo -> LimitClause -> [OrderByClause] -> (TLB.Builder, [PersistValue])
makeLimit (conn, _) (Limit ml mo) orderByClauses =
let limitRaw = connLimitOffset conn (v ml, v mo) hasOrderClause "\n"
hasOrderClause = not (null orderByClauses)
v = maybe 0 fromIntegral
in (TLB.fromText limitRaw, mempty)
makeLocking :: LockingClause -> (TLB.Builder, [PersistValue])
makeLocking = flip (,) [] . maybe mempty toTLB . Monoid.getLast
where
toTLB ForUpdate = "\nFOR UPDATE"
toTLB ForUpdateSkipLocked = "\nFOR UPDATE SKIP LOCKED"
toTLB ForShare = "\nFOR SHARE"
toTLB LockInShareMode = "\nLOCK IN SHARE MODE"
parens :: TLB.Builder -> TLB.Builder
parens b = "(" <> (b <> ")")
aliasedValueIdentToRawSql :: Ident -> IdentInfo -> (TLB.Builder, [PersistValue])
aliasedValueIdentToRawSql i info =
(useIdent info i, mempty)
valueReferenceToRawSql :: Ident -> (IdentInfo -> Ident) -> IdentInfo -> (TLB.Builder, [PersistValue])
valueReferenceToRawSql sourceIdent columnIdentF info =
(useIdent info sourceIdent <> "." <> useIdent info (columnIdentF info), mempty)
aliasedEntityColumnIdent :: Ident -> FieldDef -> Ident
aliasedEntityColumnIdent (I baseIdent) field =
I (baseIdent <> "_" <> (unDBName $ fieldDB field))
aliasedColumnName :: Ident -> IdentInfo -> T.Text -> TLB.Builder
aliasedColumnName (I baseIdent) info columnName =
useIdent info (I (baseIdent <> "_" <> columnName))
----------------------------------------------------------------------
-- | (Internal) Class for mapping results coming from 'SqlQuery'
-- into actual results.
--
-- This looks very similar to @RawSql@, and it is! However,
-- there are some crucial differences and ultimately they're
-- different classes.
class SqlSelect a r | a -> r, r -> a where
-- | Creates the variable part of the @SELECT@ query and
-- returns the list of 'PersistValue's that will be given to
-- 'rawQuery'.
sqlSelectCols :: IdentInfo -> a -> (TLB.Builder, [PersistValue])
-- | Number of columns that will be consumed.
sqlSelectColCount :: Proxy a -> Int
-- | Transform a row of the result into the data type.
sqlSelectProcessRow :: [PersistValue] -> Either T.Text r
-- | Create @INSERT INTO@ clause instead.
sqlInsertInto :: IdentInfo -> a -> (TLB.Builder, [PersistValue])
sqlInsertInto = throw (UnexpectedCaseErr UnsupportedSqlInsertIntoType)
-- | @INSERT INTO@ hack.
instance SqlSelect (SqlExpr InsertFinal) InsertFinal where
sqlInsertInto info (EInsertFinal (EInsert p _)) =
let fields = uncommas $
map (fromDBName info . fieldDB) $
entityFields $
entityDef p
table = fromDBName info . entityDB . entityDef $ p
in ("INSERT INTO " <> table <> parens fields <> "\n", [])
sqlSelectCols info (EInsertFinal (EInsert _ f)) = f info
sqlSelectColCount = const 0
sqlSelectProcessRow =
const (Right (throw (UnexpectedCaseErr InsertionFinalError)))
-- | Not useful for 'select', but used for 'update' and 'delete'.
instance SqlSelect () () where
sqlSelectCols _ _ = ("1", [])
sqlSelectColCount _ = 1
sqlSelectProcessRow _ = Right ()
unescapedColumnNames :: EntityDef -> [DBName]
unescapedColumnNames ent =
(if hasCompositeKey ent
then [] else [fieldDB (entityId ent)])
<> map fieldDB (entityFields ent)
-- | You may return an 'Entity' from a 'select' query.
instance PersistEntity a => SqlSelect (SqlExpr (Entity a)) (Entity a) where
sqlSelectCols info expr@(EEntity ident) = ret
where
process ed = uncommas $
map ((name <>) . TLB.fromText) $
entityColumnNames ed (fst info)
-- 'name' is the biggest difference between 'RawSql' and
-- 'SqlSelect'. We automatically create names for tables
-- (since it's not the user who's writing the FROM
-- clause), while 'rawSql' assumes that it's just the
-- name of the table (which doesn't allow self-joins, for
-- example).
name = useIdent info ident <> "."
ret = let ed = entityDef $ getEntityVal $ return expr
in (process ed, mempty)
sqlSelectCols info expr@(EAliasedEntity aliasIdent tableIdent) = ret
where
process ed = uncommas $
map ((name <>) . aliasName) $
unescapedColumnNames ed
aliasName columnName = (fromDBName info columnName) <> " AS " <> aliasedColumnName aliasIdent info (unDBName columnName)
name = useIdent info tableIdent <> "."
ret = let ed = entityDef $ getEntityVal $ return expr
in (process ed, mempty)
sqlSelectCols info expr@(EAliasedEntityReference sourceIdent baseIdent) = ret
where
process ed = uncommas $
map ((name <>) . aliasedColumnName baseIdent info . unDBName) $
unescapedColumnNames ed
name = useIdent info sourceIdent <> "."
ret = let ed = entityDef $ getEntityVal $ return expr
in (process ed, mempty)
sqlSelectColCount = entityColumnCount . entityDef . getEntityVal
sqlSelectProcessRow = parseEntityValues ed
where ed = entityDef $ getEntityVal (Proxy :: Proxy (SqlExpr (Entity a)))
getEntityVal :: Proxy (SqlExpr (Entity a)) -> Proxy a
getEntityVal = const Proxy
-- | You may return a possibly-@NULL@ 'Entity' from a 'select' query.
instance PersistEntity a => SqlSelect (SqlExpr (Maybe (Entity a))) (Maybe (Entity a)) where
sqlSelectCols info (EMaybe ent) = sqlSelectCols info ent
sqlSelectColCount = sqlSelectColCount . fromEMaybe
where
fromEMaybe :: Proxy (SqlExpr (Maybe e)) -> Proxy (SqlExpr e)
fromEMaybe = const Proxy
sqlSelectProcessRow cols
| all (== PersistNull) cols = return Nothing
| otherwise = Just <$> sqlSelectProcessRow cols
-- | You may return any single value (i.e. a single column) from
-- a 'select' query.
instance PersistField a => SqlSelect (SqlExpr (Value a)) (Value a) where
sqlSelectCols = materializeExpr
sqlSelectColCount = const 1
sqlSelectProcessRow [pv] = Value <$> fromPersistValue pv
sqlSelectProcessRow pvs = Value <$> fromPersistValue (PersistList pvs)
-- | Materialize a @SqlExpr (Value a)@.
materializeExpr :: IdentInfo -> SqlExpr (Value a) -> (TLB.Builder, [PersistValue])
materializeExpr info (ERaw p f) =
let (b, vals) = f info
in (parensM p b, vals)
materializeExpr info (ECompositeKey f) =
let bs = f info
in (uncommas $ map (parensM Parens) bs, [])
materializeExpr info (EAliasedValue ident x) =
let (b, vals) = materializeExpr info x
in (b <> " AS " <> (useIdent info ident), vals)
materializeExpr info (EValueReference sourceIdent columnIdent) =
valueReferenceToRawSql sourceIdent columnIdent info
-- | You may return tuples (up to 16-tuples) and tuples of tuples
-- from a 'select' query.
instance ( SqlSelect a ra
, SqlSelect b rb
) => SqlSelect (a, b) (ra, rb) where
sqlSelectCols esc (a, b) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
]
sqlSelectColCount = uncurry (+) . (sqlSelectColCount *** sqlSelectColCount) . fromTuple
where
fromTuple :: Proxy (a,b) -> (Proxy a, Proxy b)
fromTuple = const (Proxy, Proxy)
sqlSelectProcessRow =
let x = getType processRow
getType :: SqlSelect a r => (z -> Either y (r,x)) -> Proxy a
getType = const Proxy
colCountFst = sqlSelectColCount x
processRow row =
let (rowFst, rowSnd) = splitAt colCountFst row
in (,) <$> sqlSelectProcessRow rowFst
<*> sqlSelectProcessRow rowSnd
in colCountFst `seq` processRow
-- Avoids recalculating 'colCountFst'.
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
) => SqlSelect (a, b, c) (ra, rb, rc) where
sqlSelectCols esc (a, b, c) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
]
sqlSelectColCount = sqlSelectColCount . from3P
sqlSelectProcessRow = fmap to3 . sqlSelectProcessRow
from3P :: Proxy (a,b,c) -> Proxy ((a,b),c)
from3P = const Proxy
from3 :: (a,b,c) -> ((a,b),c)
from3 (a,b,c) = ((a,b),c)
to3 :: ((a,b),c) -> (a,b,c)
to3 ((a,b),c) = (a,b,c)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
) => SqlSelect (a, b, c, d) (ra, rb, rc, rd) where
sqlSelectCols esc (a, b, c, d) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
]
sqlSelectColCount = sqlSelectColCount . from4P
sqlSelectProcessRow = fmap to4 . sqlSelectProcessRow
from4P :: Proxy (a,b,c,d) -> Proxy ((a,b),(c,d))
from4P = const Proxy
from4 :: (a,b,c,d) -> ((a,b),(c,d))
from4 (a,b,c,d) = ((a,b),(c,d))
to4 :: ((a,b),(c,d)) -> (a,b,c,d)
to4 ((a,b),(c,d)) = (a,b,c,d)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
) => SqlSelect (a, b, c, d, e) (ra, rb, rc, rd, re) where
sqlSelectCols esc (a, b, c, d, e) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
]
sqlSelectColCount = sqlSelectColCount . from5P
sqlSelectProcessRow = fmap to5 . sqlSelectProcessRow
from5P :: Proxy (a,b,c,d,e) -> Proxy ((a,b),(c,d),e)
from5P = const Proxy
from5 :: (a,b,c,d,e) -> ((a,b),(c,d),e)
from5 (a,b,c,d,e) = ((a,b),(c,d),e)
to5 :: ((a,b),(c,d),e) -> (a,b,c,d,e)
to5 ((a,b),(c,d),e) = (a,b,c,d,e)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
) => SqlSelect (a, b, c, d, e, f) (ra, rb, rc, rd, re, rf) where
sqlSelectCols esc (a, b, c, d, e, f) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
]
sqlSelectColCount = sqlSelectColCount . from6P
sqlSelectProcessRow = fmap to6 . sqlSelectProcessRow
from6P :: Proxy (a,b,c,d,e,f) -> Proxy ((a,b),(c,d),(e,f))
from6P = const Proxy
from6 :: (a,b,c,d,e,f) -> ((a,b),(c,d),(e,f))
from6 (a,b,c,d,e,f) = ((a,b),(c,d),(e,f))
to6 :: ((a,b),(c,d),(e,f)) -> (a,b,c,d,e,f)
to6 ((a,b),(c,d),(e,f)) = (a,b,c,d,e,f)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
) => SqlSelect (a, b, c, d, e, f, g) (ra, rb, rc, rd, re, rf, rg) where
sqlSelectCols esc (a, b, c, d, e, f, g) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
]
sqlSelectColCount = sqlSelectColCount . from7P
sqlSelectProcessRow = fmap to7 . sqlSelectProcessRow
from7P :: Proxy (a,b,c,d,e,f,g) -> Proxy ((a,b),(c,d),(e,f),g)
from7P = const Proxy
from7 :: (a,b,c,d,e,f,g) -> ((a,b),(c,d),(e,f),g)
from7 (a,b,c,d,e,f,g) = ((a,b),(c,d),(e,f),g)
to7 :: ((a,b),(c,d),(e,f),g) -> (a,b,c,d,e,f,g)
to7 ((a,b),(c,d),(e,f),g) = (a,b,c,d,e,f,g)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
, SqlSelect h rh
) => SqlSelect (a, b, c, d, e, f, g, h) (ra, rb, rc, rd, re, rf, rg, rh) where
sqlSelectCols esc (a, b, c, d, e, f, g, h) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
, sqlSelectCols esc h
]
sqlSelectColCount = sqlSelectColCount . from8P
sqlSelectProcessRow = fmap to8 . sqlSelectProcessRow
from8P :: Proxy (a,b,c,d,e,f,g,h) -> Proxy ((a,b),(c,d),(e,f),(g,h))
from8P = const Proxy
from8 :: (a,b,c,d,e,f,g,h) -> ((a,b),(c,d),(e,f),(g,h))
from8 (a,b,c,d,e,f,g,h) = ((a,b),(c,d),(e,f),(g,h))
to8 :: ((a,b),(c,d),(e,f),(g,h)) -> (a,b,c,d,e,f,g,h)
to8 ((a,b),(c,d),(e,f),(g,h)) = (a,b,c,d,e,f,g,h)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
, SqlSelect h rh
, SqlSelect i ri
) => SqlSelect (a, b, c, d, e, f, g, h, i) (ra, rb, rc, rd, re, rf, rg, rh, ri) where
sqlSelectCols esc (a, b, c, d, e, f, g, h, i) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
, sqlSelectCols esc h
, sqlSelectCols esc i
]
sqlSelectColCount = sqlSelectColCount . from9P
sqlSelectProcessRow = fmap to9 . sqlSelectProcessRow
from9P :: Proxy (a,b,c,d,e,f,g,h,i) -> Proxy ((a,b),(c,d),(e,f),(g,h),i)
from9P = const Proxy
from9 :: (a,b,c,d,e,f,g,h,i) -> ((a,b),(c,d),(e,f),(g,h),i)
from9 (a,b,c,d,e,f,g,h,i) = ((a,b),(c,d),(e,f),(g,h),i)
to9 :: ((a,b),(c,d),(e,f),(g,h),i) -> (a,b,c,d,e,f,g,h,i)
to9 ((a,b),(c,d),(e,f),(g,h),i) = (a,b,c,d,e,f,g,h,i)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
, SqlSelect h rh
, SqlSelect i ri
, SqlSelect j rj
) => SqlSelect (a, b, c, d, e, f, g, h, i, j) (ra, rb, rc, rd, re, rf, rg, rh, ri, rj) where
sqlSelectCols esc (a, b, c, d, e, f, g, h, i, j) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
, sqlSelectCols esc h
, sqlSelectCols esc i
, sqlSelectCols esc j
]
sqlSelectColCount = sqlSelectColCount . from10P
sqlSelectProcessRow = fmap to10 . sqlSelectProcessRow
from10P :: Proxy (a,b,c,d,e,f,g,h,i,j) -> Proxy ((a,b),(c,d),(e,f),(g,h),(i,j))
from10P = const Proxy
from10 :: (a,b,c,d,e,f,g,h,i,j) -> ((a,b),(c,d),(e,f),(g,h),(i,j))
from10 (a,b,c,d,e,f,g,h,i,j) = ((a,b),(c,d),(e,f),(g,h),(i,j))
to10 :: ((a,b),(c,d),(e,f),(g,h),(i,j)) -> (a,b,c,d,e,f,g,h,i,j)
to10 ((a,b),(c,d),(e,f),(g,h),(i,j)) = (a,b,c,d,e,f,g,h,i,j)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
, SqlSelect h rh
, SqlSelect i ri
, SqlSelect j rj
, SqlSelect k rk
) => SqlSelect (a, b, c, d, e, f, g, h, i, j, k) (ra, rb, rc, rd, re, rf, rg, rh, ri, rj, rk) where
sqlSelectCols esc (a, b, c, d, e, f, g, h, i, j, k) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
, sqlSelectCols esc h
, sqlSelectCols esc i
, sqlSelectCols esc j
, sqlSelectCols esc k
]
sqlSelectColCount = sqlSelectColCount . from11P
sqlSelectProcessRow = fmap to11 . sqlSelectProcessRow
from11P :: Proxy (a,b,c,d,e,f,g,h,i,j,k) -> Proxy ((a,b),(c,d),(e,f),(g,h),(i,j),k)
from11P = const Proxy
to11 :: ((a,b),(c,d),(e,f),(g,h),(i,j),k) -> (a,b,c,d,e,f,g,h,i,j,k)
to11 ((a,b),(c,d),(e,f),(g,h),(i,j),k) = (a,b,c,d,e,f,g,h,i,j,k)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
, SqlSelect h rh
, SqlSelect i ri
, SqlSelect j rj
, SqlSelect k rk
, SqlSelect l rl
) => SqlSelect (a, b, c, d, e, f, g, h, i, j, k, l) (ra, rb, rc, rd, re, rf, rg, rh, ri, rj, rk, rl) where
sqlSelectCols esc (a, b, c, d, e, f, g, h, i, j, k, l) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
, sqlSelectCols esc h
, sqlSelectCols esc i
, sqlSelectCols esc j
, sqlSelectCols esc k
, sqlSelectCols esc l
]
sqlSelectColCount = sqlSelectColCount . from12P
sqlSelectProcessRow = fmap to12 . sqlSelectProcessRow
from12P :: Proxy (a,b,c,d,e,f,g,h,i,j,k,l) -> Proxy ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l))
from12P = const Proxy
to12 :: ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l)) -> (a,b,c,d,e,f,g,h,i,j,k,l)
to12 ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l)) = (a,b,c,d,e,f,g,h,i,j,k,l)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
, SqlSelect h rh
, SqlSelect i ri
, SqlSelect j rj
, SqlSelect k rk
, SqlSelect l rl
, SqlSelect m rm
) => SqlSelect (a, b, c, d, e, f, g, h, i, j, k, l, m) (ra, rb, rc, rd, re, rf, rg, rh, ri, rj, rk, rl, rm) where
sqlSelectCols esc (a, b, c, d, e, f, g, h, i, j, k, l, m) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
, sqlSelectCols esc h
, sqlSelectCols esc i
, sqlSelectCols esc j
, sqlSelectCols esc k
, sqlSelectCols esc l
, sqlSelectCols esc m
]
sqlSelectColCount = sqlSelectColCount . from13P
sqlSelectProcessRow = fmap to13 . sqlSelectProcessRow
from13P :: Proxy (a,b,c,d,e,f,g,h,i,j,k,l,m) -> Proxy ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),m)
from13P = const Proxy
to13 :: ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),m) -> (a,b,c,d,e,f,g,h,i,j,k,l,m)
to13 ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),m) = (a,b,c,d,e,f,g,h,i,j,k,l,m)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
, SqlSelect h rh
, SqlSelect i ri
, SqlSelect j rj
, SqlSelect k rk
, SqlSelect l rl
, SqlSelect m rm
, SqlSelect n rn
) => SqlSelect (a, b, c, d, e, f, g, h, i, j, k, l, m, n) (ra, rb, rc, rd, re, rf, rg, rh, ri, rj, rk, rl, rm, rn) where
sqlSelectCols esc (a, b, c, d, e, f, g, h, i, j, k, l, m, n) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
, sqlSelectCols esc h
, sqlSelectCols esc i
, sqlSelectCols esc j
, sqlSelectCols esc k
, sqlSelectCols esc l
, sqlSelectCols esc m
, sqlSelectCols esc n
]
sqlSelectColCount = sqlSelectColCount . from14P
sqlSelectProcessRow = fmap to14 . sqlSelectProcessRow
from14P :: Proxy (a,b,c,d,e,f,g,h,i,j,k,l,m,n) -> Proxy ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),(m,n))
from14P = const Proxy
to14 :: ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),(m,n)) -> (a,b,c,d,e,f,g,h,i,j,k,l,m,n)
to14 ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),(m,n)) = (a,b,c,d,e,f,g,h,i,j,k,l,m,n)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
, SqlSelect h rh
, SqlSelect i ri
, SqlSelect j rj
, SqlSelect k rk
, SqlSelect l rl
, SqlSelect m rm
, SqlSelect n rn
, SqlSelect o ro
) => SqlSelect (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) (ra, rb, rc, rd, re, rf, rg, rh, ri, rj, rk, rl, rm, rn, ro) where
sqlSelectCols esc (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
, sqlSelectCols esc h
, sqlSelectCols esc i
, sqlSelectCols esc j
, sqlSelectCols esc k
, sqlSelectCols esc l
, sqlSelectCols esc m
, sqlSelectCols esc n
, sqlSelectCols esc o
]
sqlSelectColCount = sqlSelectColCount . from15P
sqlSelectProcessRow = fmap to15 . sqlSelectProcessRow
from15P :: Proxy (a,b,c,d,e,f,g,h,i,j,k,l,m,n, o) -> Proxy ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),(m,n),o)
from15P = const Proxy
to15 :: ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),(m,n),o) -> (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o)
to15 ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),(m,n),o) = (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o)
instance ( SqlSelect a ra
, SqlSelect b rb
, SqlSelect c rc
, SqlSelect d rd
, SqlSelect e re
, SqlSelect f rf
, SqlSelect g rg
, SqlSelect h rh
, SqlSelect i ri
, SqlSelect j rj
, SqlSelect k rk
, SqlSelect l rl
, SqlSelect m rm
, SqlSelect n rn
, SqlSelect o ro
, SqlSelect p rp
) => SqlSelect (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) (ra, rb, rc, rd, re, rf, rg, rh, ri, rj, rk, rl, rm, rn, ro, rp) where
sqlSelectCols esc (a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p) =
uncommas'
[ sqlSelectCols esc a
, sqlSelectCols esc b
, sqlSelectCols esc c
, sqlSelectCols esc d
, sqlSelectCols esc e
, sqlSelectCols esc f
, sqlSelectCols esc g
, sqlSelectCols esc h
, sqlSelectCols esc i
, sqlSelectCols esc j
, sqlSelectCols esc k
, sqlSelectCols esc l
, sqlSelectCols esc m
, sqlSelectCols esc n
, sqlSelectCols esc o
, sqlSelectCols esc p
]
sqlSelectColCount = sqlSelectColCount . from16P
sqlSelectProcessRow = fmap to16 . sqlSelectProcessRow
from16P :: Proxy (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p) -> Proxy ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),(m,n),(o,p))
from16P = const Proxy
to16 :: ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),(m,n),(o,p)) -> (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p)
to16 ((a,b),(c,d),(e,f),(g,h),(i,j),(k,l),(m,n),(o,p)) = (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p)
-- | Insert a 'PersistField' for every selected value.
--
-- /Since: 2.4.2/
insertSelect :: (MonadIO m, PersistEntity a) =>
SqlQuery (SqlExpr (Insertion a)) -> SqlWriteT m ()
insertSelect = void . insertSelectCount
-- | Insert a 'PersistField' for every selected value, return the count afterward
insertSelectCount :: (MonadIO m, PersistEntity a) =>
SqlQuery (SqlExpr (Insertion a)) -> SqlWriteT m Int64
insertSelectCount = rawEsqueleto INSERT_INTO . fmap EInsertFinal
-- | Renders an expression into 'Text'. Only useful for creating a textual
-- representation of the clauses passed to an "On" clause.
--
-- @since 3.2.0
renderExpr :: SqlBackend -> SqlExpr (Value Bool) -> T.Text
renderExpr sqlBackend e =
case e of
ERaw _ mkBuilderValues -> do
let (builder, _) = mkBuilderValues (sqlBackend, initialIdentState)
in (builderToText builder)
ECompositeKey mkInfo ->
throw
. RenderExprUnexpectedECompositeKey
. builderToText
. mconcat
. mkInfo
$ (sqlBackend, initialIdentState)
EAliasedValue i _ ->
builderToText $ useIdent (sqlBackend, initialIdentState) i
EValueReference i i' ->
let (builder, _) = valueReferenceToRawSql i i' (sqlBackend, initialIdentState)
in (builderToText builder)
-- | An exception thrown by 'RenderExpr' - it's not designed to handle composite
-- keys, and will blow up if you give it one.
--
-- @since 3.2.0
data RenderExprException = RenderExprUnexpectedECompositeKey T.Text
deriving Show
-- |
--
-- @since 3.2.0
instance Exception RenderExprException
----------------------------------------------------------------------
-- | @valkey i = 'val' . 'toSqlKey'@
-- (<https://github.com/prowdsponsor/esqueleto/issues/9>).
valkey :: (ToBackendKey SqlBackend entity, PersistField (Key entity)) =>
Int64 -> SqlExpr (Value (Key entity))
valkey = val . toSqlKey
-- | @valJ@ is like @val@ but for something that is already a @Value@. The use
-- case it was written for was, given a @Value@ lift the @Key@ for that @Value@
-- into the query expression in a type safe way. However, the implementation is
-- more generic than that so we call it @valJ@.
--
-- Its important to note that the input entity and the output entity are
-- constrained to be the same by the type signature on the function
-- (<https://github.com/prowdsponsor/esqueleto/pull/69>).
--
-- /Since: 1.4.2/
valJ :: (PersistField (Key entity)) =>
Value (Key entity) -> SqlExpr (Value (Key entity))
valJ = val . unValue
----------------------------------------------------------------------
-- | Synonym for 'Database.Persist.Store.delete' that does not
-- clash with @esqueleto@'s 'delete'.
deleteKey :: ( PersistStore backend
, BaseBackend backend ~ PersistEntityBackend val
, MonadIO m
, PersistEntity val )
=> Key val -> R.ReaderT backend m ()
deleteKey = Database.Persist.delete
-- | Avoid N+1 queries and join entities into a map structure
-- @
-- getFoosAndNestedBarsFromParent :: ParentId -> (Map (Key Foo) (Foo, [Maybe (Entity Bar)]))
-- getFoosAndNestedBarsFromParent parentId = 'fmap' associateJoin $ 'select' $
-- 'from' $ \\(foo `'LeftOuterJoin`` bar) -> do
-- 'on' (bar '?.' BarFooId '==.' foo '^.' FooId)
-- 'where_' (foo '^.' FooParentId '==.' 'val' parentId)
-- 'pure' (foo, bar)
-- @
--
-- @since 3.1.2
associateJoin
:: forall e1 e0
. Ord (Key e0)
=> [(Entity e0, e1)]
-> Map.Map (Key e0) (e0, [e1])
associateJoin = foldr f start
where
start = Map.empty
f (one, many) =
Map.insertWith
(\(oneOld, manyOld) (_, manyNew) -> (oneOld, manyNew ++ manyOld ))
(entityKey one)
(entityVal one, [many])
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