Util-Sheet vergessen

src/Handler/Utils/Sheet.hs

@@ -0,0 +1,49 @@
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+
+module Handler.Utils.Sheet where
+
+import Import
+
+import qualified Database.Esqueleto as E
+import qualified Database.Esqueleto.Internal.Sql as E
+
+
+
+
+fetchSheetAux ::  ( BaseBackend backend ~ SqlBackend
+                  , E.SqlSelect b a
+                  , Typeable a, MonadHandler m, IsPersistBackend backend
+                  , PersistQueryRead backend, PersistUniqueRead backend
+                  )
+  =>  (E.SqlExpr (Entity Sheet) -> b)
+      -> TermId -> Text -> Text -> ReaderT backend m a
+fetchSheetAux prj tid csh shn =
+    let cachId = encodeUtf8 $ tshow (tid,csh,shn)
+    in  cachedBy cachId $ do
+    -- Mit Yesod:
+    -- cid <- getKeyBy404 $ CourseTermShort tid csh
+    -- getBy404 $ CourseSheet cid shn
+    -- Mit Esqueleto:
+        sheetList <- E.select . E.from $ \(course `E.InnerJoin` sheet) -> do
+            E.on     $ course E.^. CourseId E.==. sheet E.^. SheetCourseId
+            E.where_ $ course E.^. CourseTermId    E.==. E.val tid
+                E.&&. course E.^. CourseShorthand E.==. E.val csh
+                E.&&. sheet  E.^. SheetName       E.==. E.val shn
+            return $ prj sheet
+        case sheetList of
+          [sheet] -> return sheet
+          _other  -> notFound
+
+fetchSheet :: TermId -> Text -> Text -> YesodDB UniWorX (Entity Sheet)
+fetchSheet = fetchSheetAux id
+
+fetchSheetId :: TermId -> Text -> Text -> YesodDB UniWorX (Key Sheet)
+fetchSheetId tid cid shn = E.unValue <$> fetchSheetAux (E.^. SheetId) tid cid shn