from rest_framework import serializers, fields

from apps.music.models import *


class AlbumSerializer(serializers.Serializer):
    # 设置外键PrimaryKeyRelatedField
    artist = serializers.PrimaryKeyRelatedField(label='音乐家', queryset=Musician.objects.all(), many=False,
                                                allow_null=False)
    name = serializers.CharField(label='专辑名', required=True, max_length=10)
    # 修改字段名称并映射数据模型字段，source为指定模型的字段的字符串形式
    publish_date = serializers.DateField(label='发行日期', required=False, source='Album.release_date')
    num_stars = serializers.IntegerField(label='好评度')


class MusicianSerializer(serializers.Serializer):
    first_name = serializers.CharField(max_length=20, required=True)
    last_name = serializers.CharField(max_length=20, required=True)
    instrument = serializers.CharField(max_length=50)
    # 根据外键的关联关系，将AlbumNameSerializer做为扩展信息
    album_musician = AlbumSerializer(many=True)

    # 重写create方法
    def create(self, validated_data):
        albums_data = validated_data.pop('album_musician')
        musician = Musician.objects.create(**validated_data)
        # 插入专辑数据，artist为上一步中插入后返回的对象
        for album in albums_data:
            Album.objects.create(artist=musician, **album)
        return musician

    def update(self, instance, validated_data):
        pass


# class AlbumModelSerializer(serializers.ModelSerializer):
#     class Meta:
#         model = Album
#         fields = ('id', 'artist', 'name', 'release_date', 'num_stars')


class MusicianModelSerializer(serializers.ModelSerializer):
    # album_musician = AlbumSerializer(read_only=True, many=True)  # 定义只读外键字段后在fields中添加此键
    album_musician = AlbumSerializer(many=True)  # 定义只读外键字段后在fields中添加此键，如果需要写入create和update方法，则不应设置readonly

    class Meta:
        model = Musician
        fields = ('id', 'first_name', 'last_name', 'instrument', 'album_musician')

    # 定义创建数据的方法，用于处理外键的存储
    def create(self, validated_data):
        print(validated_data)
        albums_data = validated_data.pop('album_musician')  # 将album_musician对应的数据取出，还原Musician的原始数据格式
        musician = Musician.objects.create(**validated_data)  # 将musician数据入库， 获取返回的musician_id
        print(musician)
        for album in albums_data:
            Album.objects.create(artist=musician, **album)  # 遍历albums数据将数据入库
        return musician

    # 定义创修改的方法，用于处理外键存储
    def update(self, instance, validated_data):  # instance为pk指定的数据库对象实例
        print(instance)
        print(validated_data)
        albums_data_req = validated_data.pop('album_musician')  # 将album_musician对应的数据取出，还原Musician的原始数据格式
        albums_db = instance.album_musician.all()  # 获取原始的album外键数据
        albums_db = list(albums_db)
        print(albums_db)
        # 从validated_data中获取字段的值，如果没有获取到就取数据库实例的对应值,并且更新数据
        instance.first_name = validated_data.get('first_name', instance.first_name)
        instance.last_name = validated_data.get('last_name', instance.last_name)
        instance.instrument = validated_data.get('instrument', instance.instrument)
        instance.save()

        # 更新album数据
        for album_data_req in albums_data_req:
            album_db = albums_db.pop(0)
            album_db.name = album_data_req.get('name', album_db.name)
            album_db.release_date = album_data_req.get('release_date', album_db.release_date)
            album_db.num_stars = album_data_req.get('num_stars', album_db.num_stars)
            album_db.save()
        return instance