serializers.py 文件源码

def _check_tag_data(self, instance, validated_data):
        tag_data = validated_data['tags']
        # For PUT, check that special tags are retained and unchanged.
        if not self.partial:
            for tag in instance.special_tags:
                if tag in instance.tags and tag not in tag_data:
                    raise serializers.ValidationError(detail={
                        'detail': 'PUT requests must retain all special tags. '
                        'Your request is missing the tag: {}'.format(tag)})
        # Check that special tags are unchanged.
        for tag in instance.special_tags:
            if (tag in instance.tags and tag in tag_data and
                    tag_data[tag] != instance.tags[tag]):
                raise serializers.ValidationError(detail={
                    'detail': 'Updates (PUT or PATCH) must not attempt '
                    'to change the values for special tags. Your request '
                    'attempts to change the value for tag '
                    "'{}' from '{}' to '{}'".format(
                        tag, instance.tags[tag], tag_data[tag])})
        return tag_data