from rest_framework import serializers
from user_info.serializers import UserDescSerializer
from comment.models import Comment


class CommentChildrenSerializer(serializers.ModelSerializer):
    url = serializers.HyperlinkedIdentityField(view_name='comment-detail')
    author = UserDescSerializer(read_only=True)

    class Meta:
        model = Comment
        exclude = [  # 不需要的字段
            'parent',
            'article',
        ]


class CommentSerializer(serializers.ModelSerializer):
    """评论的序列化器"""
    # HyperlinkedIdentityField用于自身
    url = serializers.HyperlinkedIdentityField(view_name='comment-detail')
    author = UserDescSerializer(read_only=True)
    # 设置为超链接，HyperlinkedRelatedField用于对外键关系
    article = serializers.HyperlinkedRelatedField(view_name='article-detail', read_only=True)
    # 需要知道是哪篇文章的评论
    article_id = serializers.IntegerField(write_only=True, allow_null=False, required=True)
    # parent为父评论
    parent = CommentChildrenSerializer(read_only=True)
    # 本身是父评论则不需要该字段
    parent_id = serializers.IntegerField(write_only=True, allow_null=True, required=False)

    class Meta:
        model = Comment
        fields = '__all__'
        extra_kwargs = {'created': {'read_only': True}}

    # 父评论只能在创建时被关联，后续不能更改
    def update(self, instance, validated_data):
        validated_data.pop('parent_id', None)  # 更新时忽略parent_id参数
        validated_data.pop('article_id', None)  # 更新时忽略article_id参数
        return super(CommentSerializer, self).update(instance, validated_data)