Django REST外键问题

Question

尝试实现和测试我自己的序列化程序，我遇到了以下问题：

搜索了包括此错误消息在内的许多问题，但我没有找到任何解决问题的方法。

DRF 外键误用？

ValueError: Cannot assign "'effcad53-bc45-41fa-be43-4f22c0376eb5'": "Product.related_workspace" must be a "Workspace" instance.

工作区类：

class Workspace(models.Model):
    id = models.UUIDField(
            primary_key=True,
            default=uuid.uuid4,
    )
    related_login = models.ForeignKey(
            Login,
            on_delete=models.PROTECT,
    )
    description = models.CharField(
            max_length=150,
    )

    def __str__(self):
        login = Login.objects.get(pk=self.related_login_id)
        return f'{login.username} ({self.description})'

    class Meta:
        db_table = 'workspaces'

产品类：

class Product(models.Model):
    id = models.UUIDField(
            primary_key=True,
            default=uuid.uuid4,
    )
    related_workspace = models.ForeignKey(
            Workspace,
            on_delete=models.PROTECT,
    )
    code = models.CharField(
            max_length=50,
    )
    description = models.CharField(
            max_length=150,
    )

    class Meta:
        db_table = 'products'
        unique_together = ('related_workspace', 'code',)

ProductSerializer 类：

class ProductSerializer(serializers.Serializer):
    id = serializers.UUIDField(read_only=True)
    related_workspace = serializers.UUIDField()
    code = serializers.CharField()
    description = serializers.CharField()

    def create(self, validated_data):
        return Product.objects.create(**validated_data)

    def update(self, instance, validated_data):
        instance.related_workspace = validated_data.get('related_workspace', instance.related_workspace)
        instance.code = validated_data.get('code', instance.code)
        instance.description = validated_data.get('description', instance.description)
        instance.save()
        return instance

我用来测试序列化程序的脚本：

PROJECT_NAME = 'api'


def main():
    #
    from api.applications.product.models import Product
    from api.applications.product.serializers import ProductSerializer
    #
    # Create a product
    #
    code = 'P001'
    description = f'Product {code}'
    #
    # This is a valid workspace id!
    #
    related_workspace = 'effcad53-bc45-41fa-be43-4f22c0376eb5'
    #
    product = Product(
            code=code,
            description=description,
            related_workspace=related_workspace,
    )
    product.save()
    #
    serializer = ProductSerializer(product)
    print('serializer.data:', serializer.data)


if __name__ == '__main__':
    import os

    os.environ.setdefault('DJANGO_SETTINGS_MODULE', '%s.settings' % PROJECT_NAME)
    import django

    django.setup()
    main()

关于我缺少什么的任何建议？

Answer 1

首先，当您在 Django 中测试任何东西时，最简单的方法是在 test 模块中编写测试类并使用 manage.py 来运行它们。您正在执行的所有设置逻辑都已在 manage.py 中。

python manage.py test my_app.tests.my_test_class

在您的序列化程序中，您将外键设置为related_workspace = serializers.UUIDField()，而不是您想要嵌套您的序列化程序 (docs)，以便提取工作区数据、序列化、保存并返回工作区对象。你应该有两个序列化程序，它们应该看起来像这样，我将使用ModelSerializer。

from rest_framework import serializers

# Workspace Serializer
class WorkspaceSerializer(serializers.ModelSerializer):
    class Meta:
        model = Workspace
        fields = "__all__"

class ProductSerializer(serializers.ModelSerializer):
    related_workspace = WorkspaceSerializer()

    class Meta:
        model = Product
        fields = ["id", "related_workspace", "code", "description"]

    def create(self, validated_data):
        workspace_data = validated_data.pop('related_workspace')

        workspace_serializer = WorkspaceSerializer(data=workspace_data)
        if workspace_serializer.is_valid(reaise_exception=True):
            workspace = workspace_serializer.save()
            product = Product.objects.create(related_workspace = workspace, **validated_data)
            return product

我们想要删除工作区数据，然后将其提供给它自己的序列化程序，如果该数据有效，我们保存序列化程序并获得一个 Workspace 对象作为回报。然后我们可以使用返回的工作区对象创建我们的 Product 对象。

Answer 2

深入搜索，我的错误在于我创建 Product 实例的方式...

在我的测试脚本中，我刚刚更新了：

    product = Product(
            code=code,
            description=description,
            related_workspace=related_workspace,
    )

收件人：

    product = Product(
            code=code,
            description=description,
            related_workspace=Workspace.objects.get(pk=related_workspace)
    )