selectKeysList bug

When running selectKeysList on this table:

ThingOrder
  Id UUID default=uuid_generate_v1mc()
  userId UserId
  thingId ThingId
  UniqueThingId thingId
  position Int 

then we get an error:

   uncaught exception: ErrorCall
       selectKeysImpl: keyFromValues failed"DebitCardDisplayOrder: keyFromValues failed on: []"

Implementation:

    selectKeysRes filts opts = do
        conn <- ask
        srcRes <- rawQueryRes (sql conn) (getFiltsValues conn filts)
        return $ fmap (.| CL.mapM parse) srcRes
      where
        t = entityDef $ dummyFromFilts filts
        cols conn = T.intercalate "," $ toList $ dbIdColumns conn t


        wher conn = if null filts
                    then ""
                    else filterClause Nothing conn filts
        sql conn = connLimitOffset conn (limit,offset) $ mconcat
            [ "SELECT "
            , cols conn
            , " FROM "
            , connEscapeTableName conn t
            , wher conn
            , ord conn
            ]

        (limit, offset, orders) = limitOffsetOrder opts

        ord conn =
            case map (orderClause False conn) orders of
                [] -> ""
                ords -> " ORDER BY " <> T.intercalate "," ords

        parse xs = do
            keyvals <- case entityPrimary t of
                      Nothing ->
                        case xs of
                           [PersistInt64 x] -> return [PersistInt64 x]
                           [PersistDouble x] -> return [PersistInt64 (truncate x)] -- oracle returns Double
                           _ -> return xs
                      Just pdef ->
                           let pks = map fieldHaskell $ toList $ compositeFields pdef
                               keyvals = map snd $ filter (\(a, _) -> let ret=isJust (find (== a) pks) in ret) $ zip (map fieldHaskell $ getEntityFields t) xs
                           in return keyvals
            case keyFromValues keyvals of
                Right k -> return k
                Left err -> error $ "selectKeysImpl: keyFromValues failed" <> show err

So keyvals = [] which is our problem. We have a filter there which I suspect is dodgy.

Start with the selectKeysRes implementation in the issue and trace how getEntityFields, compositeFields, and keyFromValues produce keyvals. Reproduce the ThingOrder schema case, inspect why the filter yields an empty list, and verify that selectKeysList no longer fails while constructing the key.