我正在尝试设置此API,以便可以使用“PUT”更新模型“MOVIE”中某个项目上的一个/多个“TAG”。标签是MOVIE上的M2M。我正在电影中发布该商品的PK。

我的httpie工作(返回200OK),但未创建任何内容。当我发布整个JSON(使用访存)时,它只是创建TAG,但在MOVIE(link)上没有M2M关系。

httpie

http -f PUT http://localhost:8000/api/Edit/3/ tag:='{"name": "TEST"}'

型号
class Tag(models.Model):
    name = models.CharField("Name", max_length=5000, blank=True)
    taglevel = models.IntegerField("Tag level", null=True, blank=True)

class Movie(models.Model):
    title = models.CharField("Whats happening?", max_length=10000, blank=True)
    tag = models.ManyToManyField('Tag', blank=True)

Serializers.py
class Tag1Serializer(serializers.ModelSerializer):
    class Meta:
        model = Tag
        fields = ('name',)

class EditSerializer(serializers.ModelSerializer):
    tag = Tag1Serializer(many=True, read_only=True)
    class Meta:
            model = Movie
            fields = ('title', 'tag', 'info', 'created',  'status')

    def update(self, instance, validated_data):
        import pdb; pdb.set_trace()
        tags_data = validated_data.pop('tag')
        for tag_data in tags_data:
            tag_qs = Tag.objects.filter(name__iexact=tag_data['name'])
            if tag_qs.exists():
                tag = tag_qs.first()
            else:
                tag = Tag.objects.get(**tag_data)
            instance.tag.add(tag)
        return movie

Views.py
class MovieViewSet(viewsets.ModelViewSet):
    queryset = Movie.objects.all()
    serializer_class = MovieSerializer

错误:
Traceback
    tags_data = validated_data.pop('tag')
KeyError: 'tag'

最佳答案

好的。我答应了,我答应回来。这可能不是完全数据安全的,因为django尚未验证传入的数据,因此我在对python和django的相对了解中做出了一些假设。如果比我聪明的人都可以扩展这个答案,请打我一下。

注意:我坚决遵守书写软件的清洁代码标准。这些年来,它为我提供了很好的服务。我知道这不是Python代码的元数据,但是如果没有小型且重点突出的方法,它会显得草率。

Views.py

如果没有重复对象,则必须先清除相关对象,然后才能添加新对象。这是我可以为自己的用例可靠地删除m2m的唯一方法。我需要确保没有重复,并且希望有一个原子模型。你的旅费可能会改变。

class MovieViewSet(viewsets.ModelViewSet):
    queryset = Movie.objects.all()
    serializer_class = MovieSerializer

    def update(self, requiest, *args, **kwargs):
        movie = self.get_object()
        movie.tags.clear()
        return super().update(request, *args, **kwargs)

Serializers.py

由于验证器忽略m2m字段,因此必须挂接to_internal_value序列化器方法以获取所需的数据。
class Tag1Serializer(serializers.ModelSerializer):
    class Meta:
        model = Tag
        fields = ('name',)

class EditSerializer(serializers.ModelSerializer):
    tag = Tag1Serializer(many=True, read_only=True)
    class Meta:
        model = Movie
        fields = ('title', 'tag', 'info', 'created',  'status')

    def to_internal_value(self, data):
        movie_id = data.get('id')
        #if it's new, we can safely assume there's no related objects.
        #you can skip this bit if you can't make that assumption.
        if self.check_is_new_movie(movie_id):
            return super().to_internal_value(data)
        #it's not new, handle relations and then let the default do its thing
        self.save_data(movie_id, data)
        return super().to_internal_value(data)

    def check_is_new_movie(self, movie_id):
        return not movie_id

    def save_data(self, movie_id, data):
        movie = Movie.objects.filter(id=movie_id).first()
        #the data we have is raw json (string).  Listify converts it to python primitives.
        tags_data = Utils.listify(data.get('tags'))

        for tag_data in tags_data:
            tag_qs = Tag.objects.filter(name__iexact=tag_data['name'])
            #I am also assuming that the tag already exists.
            #If it doesn't, you have to handle that.
            if tag_qs.exists():
                tag = tag_qs.first()
                movie.tags.add(tag)

Utils.py
from types import *
class Utils:
#python treats strings as iterables; this utility casts a string as a list and ignores iterables
def listify(arg):
    if Utils.is_sequence(arg) and not isinstance(arg, dict):
        return arg
    return [arg,]

 def is_sequence(arg):
     if isinstance(arg, str):
         return False
     if hasattr(arg, "__iter__"):
         return True

Test.py

调整网址以使其正常工作。逻辑应该正确,但可能需要进行一些调整才能正确反射(reflect)您的模型和序列化器。这更加复杂,因为我们必须为APIClient创建json数据以与put请求一起发送。
class MovieAPITest(APITestCase):
    def setUp(self):
        self.url = '/movies/'

    def test_add_tag(self):
        movie = Movie.objects.create(name="add_tag_movie")
        tag = Tag.objects.create(name="add_tag")
        movie_id = str(movie.id)
        url = self.url + movie_id + '/'

        data = EditSerializer(movie).data
        data.update({'tags': Tag1Serializer(tag).data})
        json_data = json.dumps(data)

        self.client.put(url, json_data, content_type='application/json')
        self.assertEqual(movie.tags.count(), 1)

10-08 06:00