extra(select=None, where=None, params=None, tables=None, order_by=None, select_params=None)
Sometimes, the Django query syntax by itself can’t easily express a complex WHERE clause. For these edge cases, Django provides the extra() QuerySet modifier — a hook for injecting specific clauses into the SQL generated by a QuerySet.
Use this method as a last resort This is an old API that we aim to deprecate at some point in the future. Use it only if you cannot express your query using other quer