from django.db.backends.postgresql.introspection import DatabaseIntrospection as PostgresDatabaseIntrospection

class DatabaseIntrospection(PostgresDatabaseIntrospection):

    def get_relations(self, cursor, table_name):

        """

        Returns a dictionary of {field_index: (field_index_other_table, other_table)}

        representing all relationships to the given table. Indexes are 0-based.

        """

        cursor.execute("""

            SELECT con.conkey, con.confkey, c2.relname

            FROM pg_constraint con, pg_class c1, pg_class c2

            WHERE c1.oid = con.conrelid

                AND c2.oid = con.confrelid

                AND c1.relname = %s

                AND con.contype = 'f'""", [table_name])

        relations = {}

        for row in cursor.fetchall():

            # row[0] and row[1] are single-item lists, so grab the single item.

            relations[row[0][0] - 1] = (row[1][0] - 1, row[2])

        return relations