def autoname(self):

        """Mimic the database's automatic constraint names"""

        return "%s_pkey" % self.table.name

class ForeignKeyConstraint(ConstraintChangeset, schema.ForeignKeyConstraint):

    """Construct ForeignKeyConstraint

    Migrate's additional parameters:

    :param columns: Columns in constraint

    :param table: If columns are passed as strings, this kw is required

    :type table: Table instance

    :type columns: list of strings or Column instances

    :type refcolumns: list of strings or Column instances

    """

    __migrate_visit_name__ = 'migrate_foreign_key_constraint'

    def __init__(self, columns, refcolumns, *args, **kwargs):

        colnames, table = self._normalize_columns(columns)

        table = kwargs.pop('table', table)

        refcolnames, reftable = self._normalize_columns(refcolumns,