更新M2M关系django rest框架（很多= true）

时间：2013-04-23 08:20:06

标签： django django-rest-framework

我尝试更新频道：

PUT
content [{'url': 'http://localhost:8000/api/movies/2', 'title': u'Ariel', 'backdrop_path': u'/z2QUexmccqrvw1kDMw3R8TxAh5E.jpg', 'popularity': 0.082, 'poster_path': u'/8ld3BEg8gnynRsfj2AzbLocD8NR.jpg', 'release_date': datetime.date(1988, 10, 21), 'runtime': 69L, 'tagline': u'', 'vote_average': 9.0, 'vote_count': 0L}]
csrfmiddlewaretoken XXXXXXXXXXXXXXXXXXXXXXXXXXx
name    cody private
owner   http://localhost:8000/api/users/1
private 1

我收到了这个错误：

instance should be a queryset or other iterable with many=True

以下是您需要了解正在发生的事情的代码。

class Channel(models.Model):
    """
    A channel is a "container" for a users movies and television shows.
    """
    PUBLIC_VISIBILITY, PRIVATE_VISIBILITY = 0, 1
    VISIBILITY_CHOICES = (
        (PUBLIC_VISIBILITY, 'public'),
        (PRIVATE_VISIBILITY, 'private'),
    )
    owner = models.ForeignKey(User, related_name='owned_channels')
    name = models.CharField(max_length=60)
    content = models.ManyToManyField(Movie, db_table='channel_contents',
                                     related_name='channels', null=True, blank=True, default=None)
    subscribers = models.ManyToManyField(User, db_table='channel_subscribers',
                                         related_name='subscribed_channels', null=True, blank=True, default=None)
    created = models.DateTimeField(auto_now_add=True)
    last_mod = models.DateTimeField(auto_now=True)
    query = models.CharField(max_length=255, default='')
    private = models.IntegerField(choices=VISIBILITY_CHOICES, default=PRIVATE_VISIBILITY)

    default = models.BooleanField(default=False)


class Movie(models.Model):
    id = models.BigIntegerField(primary_key=True)
    adult = models.BooleanField()
    backdrop_path = models.ImageField(upload_to='backdrop/')
    budget = models.IntegerField(blank=True, null=True)
    genres = models.ManyToManyField('Genre',
                                    through='MovieGenre',
                                    blank=True, null=True)
    homepage = models.URLField(blank=True, null=True)
    imdb_id = models.CharField(max_length=20, blank=True, null=True)
    original_title = models.CharField(max_length=100)
    overview = models.TextField(blank=True, null=True)
    popularity = models.FloatField(blank=True, null=True)
    poster_path = models.ImageField(upload_to='poster/')
    release_date = models.DateField(blank=True, null=True)
    revenue = models.IntegerField(blank=True, null=True)
    runtime = models.IntegerField(blank=True, null=True)
    tagline = models.CharField(max_length=200, blank=True, null=True)
    title = models.CharField(max_length=100, db_index=True)
    vote_average = models.FloatField(blank=True, null=True)
    vote_count = models.IntegerField(blank=True, null=True)
    actors = models.ManyToManyField('Actor',
                                    through='MovieActor',
                                    blank=True, null=True)
    directors = models.ManyToManyField('Director',
                                       through='MovieDirector',
                                       blank=True, null=True)
    production_companies = models.ManyToManyField(
        'ProductionCompany',
        through='MovieProduction',
        blank=True, null=True)

频道序列化代码：

# Routes
url(r'^channels$', ChannelList.as_view(), name='channel-list'),
url(r'^channels/(?P<pk>\d+)$', ChannelDetail.as_view(), name='channel-detail'),

# Views
class ChannelList(generics.ListCreateAPIView):
    """
    API endpoint that represents a list of users.
    """
    model = Channel
    serializer_class = ChannelSerializer

class ChannelDetail(generics.RetrieveUpdateDestroyAPIView):
    """
    API endpoint that represents a single users.
    """
    model = Channel
    serializer_class = ChannelSerializer

# Serializer
class ChannelSerializer(serializers.HyperlinkedModelSerializer):
    content = MovieSerializer(many=True)

    class Meta:
        model = Channel
        fields = ('url', 'owner', 'name', 'content', 'private')

3 个答案:

答案 0 :(得分：3)

正如您可以阅读here，嵌套关系当前不支持写操作。请改用HyperlinkedRelatedField或编写自定义序列化程序，以实现您需要的功能。

答案 1 :(得分：2)

如果您想更新嵌套关系，可以这样做，

      class SchoolSerializer(serializers.HyperlinkedModelSerializer):

                students = StudentSerializer(many=True, read_only=True)
                students_ids = serializers.PrimaryKeyRelatedField(many=True,\
                read_only=False, queryset=Student.objects.all(),\ 
                source='students')

                class Meta:
                    model = School
                    fields = ('name', 'image', 'address', 'url',\
                    'students', 'students_ids')

使用PrimaryKeyRelatedField这将允许您通过传递id列表来创建，更新，嵌套关系（多对多字段） 学生会给你嵌套数据， students_ids可用于写操作 DRF Browsable api

答案 2 :(得分：0)

这有点过时，但是对于寻找这个问题的潜在解决方案的未来人们，我发现修补视图集很有用。

你不能两次阅读post params，这是阻止一个人传递相关更新的主键并在post_save中执行m2m更新的唯一方法

我基于ModelViewSet创建了一个自定义视图集，其中包含更新的创建和更新语句：

在您的应用中，您可以创建一个名为viewsets.py的模块：

# -*- coding: utf-8 -*-

from rest_framework import mixins
from rest_framework import status
from rest_framework.response import Response
from rest_framework.viewsets import GenericViewSet

class RelatedCreateModelMixin(mixins.CreateModelMixin):

    '''
    Monkey patch the UpdateModel for ModelViewSet Mixin to support data
    transferrance from pre - to - save - to - post
    '''

    def create(self, request, *args, **kwargs):
        data = request.DATA
        serializer = self.get_serializer(data=data, files=request.FILES)

        if serializer.is_valid():
            self.pre_save(serializer.object, data=data)
            self.object = serializer.save(force_insert=True)
            self.post_save(self.object, created=True, data=data)
            headers = self.get_success_headers(serializer.data)
            return Response(serializer.data, status=status.HTTP_201_CREATED,
                            headers=headers)

        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

class RelatedUpdateModelMixin(mixins.UpdateModelMixin):

    def update(self, request, *args, **kwargs):
        partial = kwargs.pop('partial', False)
        self.object = self.get_object_or_none()

        data = request.DATA

        serializer = self.get_serializer(self.object, data=data,
                                         files=request.FILES, partial=partial)

        if not serializer.is_valid():
            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

        try:
            self.pre_save(serializer.object, data=data)
        except ValidationError as err:
            # full_clean on model instance may be called in pre_save,
            # so we have to handle eventual errors.
            return Response(err.message_dict, status=status.HTTP_400_BAD_REQUEST)

        if self.object is None:
            self.object = serializer.save(force_insert=True)
            self.post_save(self.object, data=data, created=True)
            return Response(serializer.data, status=status.HTTP_201_CREATED)

        self.object = serializer.save(force_update=True)
        self.post_save(self.object, created=False)
        return Response(serializer.data, status=status.HTTP_200_OK)


class RelatedModelViewSet(RelatedCreateModelMixin,
                          mixins.RetrieveModelMixin,
                          RelatedUpdateModelMixin,
                          mixins.DestroyModelMixin,
                          mixins.ListModelMixin,
                          GenericViewSet):
    pass

然后，在您的视图中，改为使用：

from MYAPP import viewsets

这使您可以按照以下方式执行某些操作：

def post_save(self, obj, *args, **kwargs):
    data = kwargs.get('data')
    model_id = data.get('id')
    parent_obj = Model.objects.get(id=model_id)
    method = self.request.method
    if method == 'POST':
        parent_obj.m2m.add(obj)
    elif method == 'PUT':
        parent_obj.m2m.remove(obj)

不是最优雅的解决方案，但我发现它更适合编写自定义序列化程序

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