class CommentCreateSerializer(serializers.ModelSerializer):
    commenter_pw = serializers.CharField(max_length=32, write_only=True,
        required=False)


class Meta:
    model = Comment
fields = ('email', 'author', 'url', 'content', 'ip', 'post_title',
    'post_url', 'commenter_pw')
Adding field that isn't in model to serializer in Django REST framework