使用 ManyToManyField 的序列化模型缺少数据

Question

这是我的例子：

models.py：

class Example(models.Model):
    title = models.CharField(...)
    description = models.CharField(...)

class Foo(models.Model):
    example = models.ManyToManyField(Example)

serializers.py：

class FooSerializer(serializers.ModelSerializer):
    class Meta:
        model = Foo
        fields = '__all__'
        depth = 1

views.py：

...
serialized_data = [FooSerializer(foo).data for foo in Foo.objects.all().get]

在输出中，我只收到Example 的 ID，但有什么方法可以让我也获得标题和描述字段（m2mfield 的详细信息）？据我了解，Foo.objects.all().get 根本不包含此数据，但也许我可以以某种方式获取并使用它？ 如果需要，我也可以重建模型，但目前我使用 m2mf，因为需要包含与此模型数据相关的多个对象。

更新

models.py：

class Event(models.Model):
    ts = models.BigIntegerField(editable=False)

class Foo(Event):
    user = models.ForeignKey(User, ...)
    example = *...(remains to be the same)*
    foos = models.ForeignKey('self', **somemore** null=True)

serializers.py：

class EventSerializer(serializers.ModelSerializer):

    class Meta:
        model = Event
        fields = '__all__'

    def to_representation(self, instance):
        result = {'ts': instance.ts}
        if isinstance(instance, Foo):
            result['foo'] = FooSerializer(instance).data
        return result

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        fields = ('id', 'username')

class FooSerializer(serializers.ModelSerializer):
   # user = UserSerializer(read_only=True) # with this I have an error: Got AttributeError when attempting to get a value for field 'username' on #serializer 'UserSerializer'

    class Meta:
        model = Foo
        fields = '__all__'
        depth = 1

Answer 1

您可以使用depth 属性来实现所需的输出。

默认的 ModelSerializer 使用主键来表示关系，但是 您还可以使用 depth 轻松生成嵌套表示 option.The depth 选项应该设置为一个整数值 表示之前应该遍历的关系深度 恢复为平面表示。

class FooSerializer(serializers.ModelSerializer):
    class Meta:
        model = Foo
        fields = '__all__'
        depth = 1

除了答案，我想更改您的 views.py 代码，因为它看起来很糟糕 :(。在 DRF 方式 上做

serialized_data = FooSerializer(Foo.objects.all(), many=True).data<br>

示例视图

from rest_framework.viewsets import ModelViewSet


class FooViewset(ModelViewSet):
    serializer_class = FooSerializer
    queryset = Foo.objects.all()

UPDATE-1

class UserSerializer(serializers.ModelSerializer):
    class Meta:
        model = User
        exclude = ('password',) # add fields that are need to be excluded 


class FooSerializer(serializers.ModelSerializer):
    user = UserSerializer()

    class Meta:
        model = Foo
        fields = '__all__'
        depth = 1

depth = 1将序列化model中的all字段，（与在序列化的Meta类中设置fields=='__all__'相同）


UPDATE-2

class FooSerializer(serializers.ModelSerializer):
    user = UserSerializer()

    class Meta:
        model = Foo
        fields = '__all__'
        depth = 1

    def to_representation(self, instance):
        real_data = super().to_representation(instance).copy()
        # DO YOUR EXTRA CHECKS
        child = UserSerializer(instance.child_foo).data
        if child:
            real_data.update({"child_data": child})
        # After your checks, add it to "real_data"
        return real_data

我假设我有一个Foo 模型

class Foo(models.Model):
    example = models.ManyToManyField(Example)
    user = models.ForeignKey(User)
    child_foo = models.ForeignKey('self', null=True, blank=True)

Answer 2

在您的序列化程序中添加深度 = 1。“用户”是相关字段的示例：

FooSerializer(serializers.ModelSerializer):
    class Meta:
        model = Foo
        fields = ('id', 'account_name', 'users', 'created')
        depth = 1