belongsToJust ::
  ( PersistStoreRead backend
  , PersistEntity ent1
  , PersistRecordBackend ent2 backend
  , MonadIO m
  )
  => (ent1 -> Key ent2) -> ent1 -> ReaderT backend m ent2
belongsToJust getForeignKey model = getJust $ getForeignKey model
belongsToJust ::
  ( PersistStoreRead backend
  , PersistEntity ent1
  , PersistRecordBackend ent2 backend
  , MonadIO m
  )
  => (ent1 -> Key ent2) -> ent1 -> ReaderT backend m ent2
belongsToJust getForeignKey model = getJust $ getForeignKey model
belongsToJust getForeignKey model = getJust $ getForeignKey model