在 Django 中使用嵌套序列化程序创建 2 个相关模型的实例

Question

我是 Django 的新手，我在我的代码中遇到过这个问题。我有一个自定义用户模型和一个帐户模型，它们由多对多字段关联。

在注册过程中，系统会要求用户创建或不创建帐户（通过 link 加入其他帐户）。

如果用户创建了一个帐户，那么他就是该帐户的所有者，其他用户可以加入该帐户。(Did not finish the code for ownership)
一个用户可以同时是多个帐户的一部分。
在注册视图中创建（或不创建）帐户和用户。

我在文档中阅读了有关嵌套序列化程序的信息，我认为这应该创建两个模型实例。如何使用嵌套序列化程序在一个视图中创建关系？解决问题的其他方法？

型号

class Account(models.Model):
    AccountName = models.TextField(max_length=100, blank=False, null=False)

class User(AbstractBaseUser):
    AccountName = models.ManyToManyField(Account)
    CreateAccount = models.BooleanField(blank=False, null=False)
    EmailId = models.EmailField(max_length=128, blank=False, null=False, unique=True)

    is_admin = models.BooleanField(default=False)
    is_active = models.BooleanField(default=True)
    is_staff = models.BooleanField(default=False)
    is_superuser = models.BooleanField(default=False)

    USERNAME_FIELD = 'EmailId'
    REQUIRED_FIELDS = ['AccountName', 'CreateAccount',]

    # Implemented the other req. functions

    objects = MyAccountManager()

序列化程序

class AccountCreationSerializer(ModelSerializer):
    class Meta:
        model = Account
        fields = ['AccountName']

class SignUpSerializer(ModelSerializer):

    AccountName = AccountCreationSerializer()

    class Meta:
        model = User
        fields = ['EmailId', 'AccountName', 'CreateAccount', 'password']
        extra_kwargs = {'password': {'write_only': True, 'required': True}}

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

        if validated_data['CreateAccount']: #Create only when this is True
            Account.objects.create(AccountName=AccountName, **AccountName)

        userAcc = User.objects.create_user(**validated_data)

        return userAcc

查看

class SignUpView(APIView):

    def post(request):
        # to edit
        signup_serializer = SignUpSerializer(data=request.data)
        
        # rest of the view

要求 // 忽略引号

EmailID: xyz@gmail.com
AccountName: TestAcc
CreateAccount: False
Password: ****

错误： Direct assignment to the forward side of a many-to-many set is prohibited. Use AccountName.set() instead.

Create_user 自定义模型

    def create_user(self, EmailId, AccountName, CreateAccount, password):
        if not EmailId:
            raise ValueError("Users must have an email")

        user = self.model(
            EmailId=self.normalize_email(EmailId),
            AccountName=AccountName,
            CreateAccount=CreateAccount,
        )

        user.set_password(password)
        user.save(using=self._db)
        return user

我很确定我在 manytomany 领域犯了一些错误，但一直无法找出解决方案。任何帮助都会对我有益。 TIA！

Answer 1

您不能将值直接保存到 many-to-many 字段。数据库不允许你这样做。它只允许您添加它们以关联两个表之间的关系（ i.e User, Account ）。将 Serializer 文件的代码段替换为以下代码段。

class AccountCreationSerializer(ModelSerializer):
    class Meta:
        model = Account
        fields = ['AccountName']


class SignUpSerializer(ModelSerializer):
    AccountName = serializers.SerializerMethodField()

    class Meta:
        model = User
        fields = ['EmailId', 'AccountName', 'CreateAccount', 'password']
        extra_kwargs = {'password': {'write_only': True, 'required': True}}

    def validate(self, attrs):
        attrs = super(SignUpSerializer, self).validate(attrs=attrs)
        attrs.update({"AccountName": self.initial_data.get("AccountName")})
        return attrs

    def create(self, validated_data):
        AccountName = validated_data.pop('AccountName')
        acc = Account.objects.create(AccountName=AccountName) if "CreateAccount" in validated_data and validated_data['CreateAccount'] else None

        userAcc = User.objects.create_user(**validated_data)
        if acc:
            userAcc.AccountName.add(acc)

        return userAcc

最后，将你的SignUpViewclass替换成下面的方式：

class SignUpView(APIView):
    serializer_class = SignUpSerializer

    def post(self, request, *args, **kwargs):
        serializer = self.serializer_class(data=request.data)
        is_valid_serializer = serializer.is_valid(raise_exception=True)
        if is_valid_serializer:
            with transaction.atomic():
                serializer.save()
        # Rest of your code segments to finalize the response

更新

您的 create_user 方法有问题。您在这里传递了 many-to-many 字段引用 (AccountName)，这是您不应该传递的。正如我前面提到的，您不能直接保存 many-to-many 字段。你只需要关联它们之间的关系。忽略它，它将起作用！！！

遵循此方法的新定义 (create_user)。

    def create_user(self, EmailId, CreateAccount, password):
        if not EmailId:
            raise ValueError("Users must have an email")

        user = self.model(EmailId=self.normalize_email(EmailId), CreateAccount=CreateAccount)

        user.set_password(password)
        user.save(using=self._db)
        return user

在 Django 中使用嵌套序列化程序创建 2 个相关模型的实例

Creating instances of 2 related models using nested serializer in Django

python

django

many-to-many

django-rest-framework