Fix location header for inserted objects with nulls

src/App.hs

@@ -112,7 +112,7 @@ app v1schema reqBody req =
             then inserted
             else filterWithKey (const . (`elem` primaryKeys)) inserted
         let params = urlEncodeVars
-              $ map (\t -> (cs $ fst t, "eq." <> cs (unquoted $ snd t)))
+              $ map (\t -> (cs $ fst t, cs (paramFilter $ snd t)))
               $ sortBy (comparing fst) $ toList primaries
         return $ responseLBS status201
           [ jsonH

src/PgQuery.hs

@@ -237,3 +237,7 @@ unquoted _ = ""
 insertableValue :: JSON.Value -> T.Text
 insertableValue JSON.Null = "null"
 insertableValue v = ((<> "::unknown") . pgFmtLit . unquoted) v
+
+paramFilter :: JSON.Value -> T.Text
+paramFilter JSON.Null = "is.null"
+paramFilter v = "eq." <> unquoted v