Explicitly disable FK constraints in SQLite editor

    sql_delete_table = "DROP TABLE %(table)s"

    sql_create_inline_fk = "REFERENCES %(to_table)s (%(to_column)s)"

    def __enter__(self):

        with self.connection.cursor() as c:

            # Some SQLite schema alterations need foreign key constraints to be

            # disabled. This is the default in SQLite but can be changed with a

            # build flag and might change in future, so can't be relied upon.

            # We enforce it here for the duration of the transaction.

            c.execute('PRAGMA foreign_keys')

            self._initial_pragma_fk = c.fetchone()[0]

            c.execute('PRAGMA foreign_keys = 0')

        return super(DatabaseSchemaEditor, self).__enter__()

    def __exit__(self, exc_type, exc_value, traceback):

        super(DatabaseSchemaEditor, self).__exit__(exc_type, exc_value, traceback)

        with self.connection.cursor() as c:

            # Restore initial FK setting - PRAGMA values can't be parametrized

            c.execute('PRAGMA foreign_keys = %s' % int(self._initial_pragma_fk))

    def quote_value(self, value):

        try:

            value = _sqlite3.adapt(value)