django - DRF多对一反向查询

Question

我有一个API端点，返回宠物及其主人。

每个所有者都有一个名字和一个或多个宠物

每只宠物都有一个名字和一个所有者

Django模型示例:

class Owner(models.Model):
    name = models.CharField(max_length=200)

class Pet(models.Model):
    owner = models.ForeignKey(Owner, on_delete=models.CASCADE)
    name = models.CharField(max_length=200)

我已经将我的API配置为返回JSON数据，如下所示:

[
    {
        "id": 2,
        "name": "Scotch",
        "owner": {
            "id": 2,
            "name": "Ben"
        }
    },
    {
        "id": 3,
        "name": "Fluffy",
        "owner": {
            "id": 1,
            "name": "Fred"
        }
    },
    {
        "id": 1,
        "name": "Spot",
        "owner": {
            "id": 1,
            "name": "Fred"
        }
    }
]

DRF序列化器示例:

class OwnerSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = Owner
        fields = ("id", "name")

class PetSerializer(serializers.HyperlinkedModelSerializer):
    owner = OwnerSerializer()
    class Meta:
        model = Pet
        fields = ("id", "name", "owner")

尽管这一切都很好，但我实际上想要一个可以返回所有者及其宠物列表的终结点。因此，我将获得以下数据:

[
    {
        "id": 1,
        "name": "Fred",
        "pets": [
            { "id": 1, "name": "Spot" },
            { "id": 3, "name": "Fluffy" }
        ]
    },
    {
        "id": 2,
        "name": "Ben",
        "pets": [
            { "id": 2, "name": "Scotch" }
        ]
    }
]

如何获得该输出？

Answer 1

您需要像这样将pet_set字段添加到OwnerSerializer:

class PetSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = Pet
        fields = ("id", "name")

class OwnerSerializer(serializers.HyperlinkedModelSerializer):
    pet_set = PetSerializer(many=True, read_only=True)
    class Meta:
        model = Owner
        fields = ("id", "name", "pet_set")

这将起作用，因为在您的情况下，多对一关系默认反向查找名称是<model>_set或pet_set。您可以使用related_name进行更改:

class Pet(models.Model):
    owner = models.ForeignKey(Owner, related_name='pets', on_delete=models.CASCADE)

在这种情况下，您可以在序列化程序中使用pets名称:

class OwnerSerializer(serializers.HyperlinkedModelSerializer):
    pets = PetSerializer(many=True, read_only=True)

现在在OwnerListView中，您可以使用此新的序列化器:

class OwnerListView(ListAPIView):
    queryset = Owner.objects.all()
    serializer_class = OwnerSerializer