Method get_extra_restriction

django/db/models/fields/related.py:869–881

Return a pair condition used for joining and subquery pushdown. The condition is something that responds to as_sql(compiler, connection) method. Note that currently referring both the 'alias' and 'related_alias' will not work in some conditions, like subquer

(self, alias, related_alias)

        return {}

    def get_extra_restriction(self, alias, related_alias):
        """
        Return a pair condition used for joining and subquery pushdown. The
        condition is something that responds to as_sql(compiler, connection)
        method.

        Note that currently referring both the 'alias' and 'related_alias'
        will not work in some conditions, like subquery pushdown.

        A parallel method is get_extra_descriptor_filter() which is used in
        instance.fieldname related object fetching.
        """
        return None

    def get_path_info(self, filtered_relation=None):
        """Get path from this field to the related model."""