def prepare_value(self, value):
    if isinstance(value, ModelBase):
        value = ('%s.%s' % (value._meta.app_label, value._meta.model_name))
    return value
def prepare_value(self, value):
    if isinstance(value, ModelBase):
        value = ('%s.%s' % (value._meta.app_label, value._meta.model_name))
    return value