Change aliased val to be legal value by waiting until expr materialization in select clause before adding AS <alias>

src/Database/Esqueleto/Experimental/ToAlias.hs

@@ -16,15 +16,11 @@ class ToAlias a where
     toAlias :: a -> SqlQuery a
 
 instance ToAlias (SqlExpr (Value a)) where
-    toAlias (ERaw m f) =
-        case sqlExprMetaAlias m of
-            Just _ -> pure $ ERaw m f
-            Nothing -> do
-                ident <- newIdentFor (DBName "v")
-                pure $ ERaw noMeta{sqlExprMetaAlias = Just ident} $ \_ info ->
-                    let (b, v) = f Never info
-                    in (b <> " AS " <> useIdent info ident, v)
-
+    toAlias e@(ERaw m f)
+      | Just _ <- sqlExprMetaAlias m, not (sqlExprMetaIsReference m) = pure e
+      | otherwise = do
+            ident <- newIdentFor (DBName "v")
+            pure $ ERaw noMeta{sqlExprMetaAlias = Just ident} f
 
 instance ToAlias (SqlExpr (Entity a)) where
     toAlias (ERaw m f) = do

src/Database/Esqueleto/Internal/Internal.hs

@@ -3044,11 +3044,11 @@ instance PersistField a => SqlSelect (SqlExpr (Value a)) (Value a) where
 
 -- | Materialize a @SqlExpr (Value a)@.
 materializeExpr :: IdentInfo -> SqlExpr (Value a) -> (TLB.Builder, [PersistValue])
-materializeExpr info v
-    | ERaw m _ <- v, Just f <- sqlExprMetaCompositeFields m = 
-        let bs = f info
-        in (uncommas $ map (parensM Parens) bs, [])
-    | ERaw _ f <- v = f Parens info
+materializeExpr info (ERaw m f)
+    | Just fields <- sqlExprMetaCompositeFields m = (uncommas $ fmap parens $ fields info, [])
+    | Just alias <- sqlExprMetaAlias m
+    , not (sqlExprMetaIsReference m) = first (<> " AS " <> useIdent info alias) (f Parens info)
+    | otherwise = f Parens info
 
 
 -- | You may return tuples (up to 16-tuples) and tuples of tuples