That's how it was working initially - I've passed it to constructor, but it turns out it only needed in `to_sql` method to resolve full column name (`table.column` VS just `column`). The problem that I am also using `OrderClause` in view helper `current_sort` which does not have direct access to active admin config object. It never calls `to_sql` in fact, so making `active_admin_config` an optional constructor parameter will work (assuming that some exception will be raised in `to_sql` if `active_admin_config` was not set), but I still think it should be passed as parameter to `to_sql`.