Changing Favourite Setting immediately deletes superfluous favorites.

src/Foundation.hs

@@ -417,7 +417,7 @@ instance Yesod UniWorX where
                                   [ Desc CourseFavouriteTime
                                   , OffsetBy $ userMaxFavourites user
                                   ]
-              lift $ mapM delete oldFavs
+              lift $ mapM_ delete oldFavs
 
           _other -> return ()
       return res

src/Handler/Profile.hs

@@ -47,9 +47,18 @@ getProfileR = do
   ((res,formWidget), formEnctype) <- runFormPost $ makeSettingForm settingsTemplate
   case res of
     (FormSuccess SettingsForm{..}) -> do
-        runDB $ update uid  [ UserMaxFavourites =. stgMaxFavourties
-                            , UserTheme         =. stgTheme
-                            ]
+        runDB $ do
+          update uid  [ UserMaxFavourites =. stgMaxFavourties
+                      , UserTheme         =. stgTheme
+                      ]
+          when (stgMaxFavourties < userMaxFavourites) $ do
+            -- prune Favourites to user-defined size
+            oldFavs <- selectKeysList [ CourseFavouriteUser ==. uid]
+                                      [ Desc CourseFavouriteTime
+                                      , OffsetBy $ stgMaxFavourties
+                                      ]
+            mapM_ delete oldFavs
+
         addMessageI "info" $ MsgSettingsUpdate
     (FormFailure msgs) -> forM_ msgs $ (addMessage "warning") . toHtml
     _ -> return ()