74 lines
2.4 KiB
Haskell
74 lines
2.4 KiB
Haskell
{-# OPTIONS_GHC -fno-warn-orphans #-}
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module Database.Esqueleto.Utils
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( true, false
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, isInfixOf, hasInfix
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, any, all
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, SqlIn(..)
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, mkInFilter
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) where
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import ClassyPrelude.Yesod hiding (isInfixOf, any, all)
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import qualified Data.Set as Set
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import qualified Data.Foldable as F
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import qualified Database.Esqueleto as E
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import Database.Esqueleto.Utils.TH
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--
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-- Description : Convenience for using @Esqueleto@,
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-- intended to be imported qualified
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-- just like Esqueleto
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-- ezero = E.val (0 :: Int64)
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-- | Often needed with this concrete type
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true :: E.SqlExpr (E.Value Bool)
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true = E.val True
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-- | Often needed with this concrete type
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false :: E.SqlExpr (E.Value Bool)
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false = E.val False
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-- | Check if the first string is contained in the text derived from the second argument
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isInfixOf :: (E.Esqueleto query expr backend, E.SqlString s2) =>
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Text -> expr (E.Value s2) -> expr (E.Value Bool)
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isInfixOf needle strExpr = E.castString strExpr `E.ilike` (E.%) E.++. E.val needle E.++. (E.%)
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hasInfix :: (E.Esqueleto query expr backend, E.SqlString s2) =>
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expr (E.Value s2) -> Text -> expr (E.Value Bool)
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hasInfix = flip isInfixOf
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-- | Given a test and a set of values, check whether anyone succeeds the test
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-- WARNING: SQL leaves it explicitely unspecified whether || is short curcuited (i.e. lazily evaluated)
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any :: Foldable f =>
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(a -> E.SqlExpr (E.Value Bool)) -> f a -> E.SqlExpr (E.Value Bool)
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any test = F.foldr (\needle acc -> acc E.||. test needle) false
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-- | Given a test and a set of values, check whether all succeeds the test
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-- WARNING: SQL leaves it explicitely unspecified whether && is short curcuited (i.e. lazily evaluated)
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all :: Foldable f =>
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(a -> E.SqlExpr (E.Value Bool)) -> f a -> E.SqlExpr (E.Value Bool)
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all test = F.foldr (\needle acc -> acc E.&&. test needle) true
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$(sqlInTuples [2..16])
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-- | generic filter creation for dbTable
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-- Given a lens-like function, make filter
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-- What I thought:
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-- mkFilter :: (Foldable f, E.From query expr backend a)
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-- => (a -> E.SqlExpr (E.Value b))
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-- -> a
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-- -> f b
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-- -> E.SqlExpr (E.Value Bool)
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-- What is inferred:
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mkInFilter :: (PersistField a)
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=> (t -> E.SqlExpr (E.Value a))
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-> t
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-> Set.Set a
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-> E.SqlExpr (E.Value Bool)
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mkInFilter lenslike row criterias
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| Set.null criterias = true
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| otherwise = (lenslike row) `E.in_` E.valList (Set.toList criterias) |