Improve AvatarR performance by only fetching the avatar from the DB, not the whole User

src/Handler/Avatars.hs

@@ -1,12 +1,17 @@
+{-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE OverloadedStrings #-}
 module Handler.Avatars where
 
-import Import
+import Import hiding ( (==.) )
 
-import Model.Cache ( getCached )
+import Database.Esqueleto
 import Settings.StaticR ( staticR ) 
 
 getAvatarR :: UserId -> Handler ()
-getAvatarR = redirect <=< fmap (avatarR . entityVal) . getCached
-    where avatarR user = staticR ["img", userAvatar user]
+getAvatarR = responseFrom <=< runDB . select . from . queryAvatar
+    where responseFrom (a:_) = redirect $ staticR ["img", unValue a]
+          responseFrom    [] = notFound
+          queryAvatar userId user = do
+              where_ $ user ^. UserId ==. val userId
+              return $ user ^. UserAvatar