Question

我有以下模特：

class Song(models.Model):
    name = models.CharField(max_length=64)

    def __unicode__(self):
        return self.name

class UserProfile(AbstractUser):
    current = models.ManyToManyField(Song, related_name="in_current", blank=True)
    saved = models.ManyToManyField(Song, related_name="in_saved", blank=True)
    whatever = models.ManyToManyField(Song, related_name="in_whatever", blank=True)

    def __unicode__(self):
        return self.get_username()

以及以下序列化程序：

class SongSerializer(serializers.ModelSerializer):
    class Meta:
        model = Song

class UserProfileSongsSerializer(serializers.ModelSerializer):
    current = SongSerializer(many=True)
    saved = SongSerializer(many=True)
    whatever = SongSerializer(many=True)

    class Meta:
        model = UserProfile
        fields = ("id", "current", "saved", "whatever")

我正在使用UpdateAPIView：

class UserProfileSongsUpdate(generics.UpdateAPIView):
    queryset = UserProfile.objects.all()
    serializer_class = UserProfileSongsSerializer

问题：我无法将歌曲（即使它已经存在于数据库中）添加到任何（当前，已保存，无论如何），我只能删除它。

curl -X PUT -d '{"current": [{"id": 1, "name": "sialalalal"}, {"id": 2, "name": "imissmykitty"}], "saved": [{"id": 3, "name": "kittyontheroad"}], "whatever": []}' -H "Content-Type:application/json" localhost:8000/userprofile/1/songs/update/

这将删除当前集合中的所有其他歌曲（这很好:)），但是当我尝试将现有歌曲添加到当前集合时它会告诉我一个错误：

curl -X PUT -d '{"current": [{"id": 1, "name": "sialalalal"}, {"id": 2, "name": "imissmykitty"}, {"id": 7, "name": "vivalakita"}], "saved": [{"id": 3, "name": "kittyontheroad"}], "whatever": []}' -H "Content-Type:application/json" localhost:8000/userprofile/1/songs/update/

我明白了：

{"current": [{}, {}, {"non_field_errors": ["Cannot create a new item, only existing items may be updated."]}]}

BUT！如果我删除序列化字段：

class UserProfileSongsSerializer(serializers.ModelSerializer):

    class Meta:
        model = UserProfile
        fields = ("id", "current", "saved", "whatever")

我做了：

curl -X PUT -d '{"current": [1, 2, 7], "saved": [3], "whatever": []}' -H "Content-Type:application/json" localhost:8000/userprofile/1/songs/update/

它添加了没有任何问题的歌曲......

我可以使用序列化程序作为字段添加和删除当前和已保存等集合中的歌曲吗？

Answer 1

是的，你可以。您需要将allow_add_remove设置为True，将read_only设置为False：

current = SongSerializer(many=True, allow_add_remove=True, read_only=False)

请注意，嵌套序列化程序的当前实现将从DB中删除整个Song对象，而不仅仅是关系。

使用序列化程序作为字段时，无法更新m2m

1 个答案: