Favourites updated immediately now; Links for Lecturers are shown

src/Foundation.hs

@@ -395,9 +395,9 @@ instance Yesod UniWorX where
     -- To add it, chain it together with the defaultMiddleware: yesodMiddleware = defaultYesodMiddleware . defaultCsrfMiddleware
     -- For details, see the CSRF documentation in the Yesod.Core.Handler module of the yesod-core package.
     yesodMiddleware handler = do
-      res <- defaultYesodMiddleware handler
       void . runMaybeT $ do
         route <- MaybeT getCurrentRoute
+        guardM . lift $ (== Authorized) <$> isAuthorized route False
         case route of -- update Course Favourites here
           CourseR tid csh _  -> do
             uid <- MaybeT maybeAuthId
@@ -420,6 +420,7 @@ instance Yesod UniWorX where
               lift $ mapM_ delete oldFavs
 
           _other -> return ()
+      res <- defaultYesodMiddleware handler -- handler is executed before Favourites are update
       return res
 
     defaultLayout widget = do
@@ -600,10 +601,15 @@ pageActions (CourseR tid csh CShowR) =
       , menuItemRoute = CourseR tid csh SheetListR
       , menuItemAccessCallback' = do --TODO always show for lecturer
           let sheetRouteAccess shn = (== Authorized) <$> (isAuthorized (CSheetR tid csh shn SShowR) False)
-          sheets <-runDB $ do
+          muid <- maybeAuthId
+          (sheets,lecturer) <- runDB $ do
             cid <- getKeyBy404 $ CourseTermShort tid csh
-            map (sheetName.entityVal) <$> selectList [SheetCourse ==. cid] [Desc SheetActiveFrom]
-          anyM sheets sheetRouteAccess
+            sheets <- map (sheetName.entityVal) <$> selectList [SheetCourse ==. cid] [Desc SheetActiveFrom]
+            lecturer <- case muid of
+                Nothing    -> return False
+                (Just uid) -> existsBy $ UniqueLecturer uid cid
+            return (sheets,lecturer)
+          or2M (return lecturer) $ anyM sheets sheetRouteAccess
       }
   , PageActionSecondary $ MenuItem
       { menuItemLabel = "Neues Übungsblatt anlegen"

src/Utils.hs

@@ -210,6 +210,9 @@ shortCircuitM sc mx my op = do
     False -> op <$> pure x <*> my
 
 
+guardM :: MonadPlus m => m Bool -> m ()
+guardM f = guard =<< f
+
 -- Some Utility Functions from Agda.Utils.Monad
 -- | Monadic if-then-else.
 ifM :: Monad m => m Bool -> m a -> m a -> m a

src/Utils/DB.hs

@@ -25,6 +25,10 @@ getKeyBy404 :: (PersistEntityBackend record ~ BaseBackend backend, PersistEntity
   => Unique record -> ReaderT backend m (Key record)
 getKeyBy404 = (fmap entityKey) . getBy404 -- TODO optimize this, so that DB does not deliver entire record!
 
+existsBy :: (PersistEntityBackend record ~ BaseBackend backend, PersistEntity record, PersistUniqueRead backend, MonadIO m)
+  => Unique record -> ReaderT backend m Bool
+existsBy = fmap isJust . getBy
+
 
 myReplaceUnique
     :: (MonadIO m