models.py

class PGArrayField(models.Field):
    """ Custom field for mapping between postgresql array and python list."""

    def __init__(self, element_field, **kwargs):
        self.element_field = element_field
        models.Field.__init__(self, **kwargs)

    def db_type(self, *connection):
        return '%s[]' % self.element_field.db_type(*connection)

    def to_python(self, value):
        # psycopg2 handles arrays with care
        return value