Django REST Framework注册接口触发RecursionError问题求助

问题描述 #

使用Django REST Framework开发的用户注册接口此前运行正常，近期测试时触发RecursionError: maximum recursion depth exceeded错误。

相关代码 #

serializers.py #

class RegisterSerializer(serializers.ModelSerializer):
    password = serializers.CharField(
        write_only=True,
        max_length=68,
        min_length=8,
        error_messages={"min_length": f"Password must be longer than {MIN_LENGTH}characters"},
        required=True,
        validators=[validate_password]
    )
    password2 = serializers.CharField(
        write_only=True,
        max_length=68,
        min_length=8,
        error_messages={"min_length": f"Password must be longer than {MIN_LENGTH}characters"},
        required=True
    )

    class Meta:
        model = User
        fields = ('username','phone','password','password2')

    # 错误位置：extra_kwargs定义在Meta类外部
    extra_kwargs = {
        'password': {'write_only': True},
        'password2': {'write_only': True}
    }
    
    def validate(self,data):
        if data["password"]!=data["password2"]:
            raise serializers.ValidationError("password does not match!")
        return data

    def create(self,validated_data):
        # 不规范：使用self.validated_data而非传入的参数
        user = User.objects.create(
            phone=self.validated_data['phone'],
            username=self.validated_data['username'],
        )
        user.set_password(validated_data['password'])
        user.save()
        return user 

views.py #

class RegisterViewSet(viewsets.ModelViewSet):
    http_method_names = ['post']
    '''This endpoint is made to register all user with phone number and password'''
    queryset = User.objects.all()
    serializer_class = RegisterSerializer

错误原因 #

1. extra_kwargs配置位置错误：ModelSerializer的extra_kwargs必须定义在class Meta内部，当前定义在外部会导致DRF无法识别该配置，进而在序列化返回的用户对象时，无法正确应用write_only属性，触发无限递归的字段处理逻辑。
2. create方法参数使用不规范：create方法中使用self.validated_data而非传入的validated_data参数，虽不直接引发递归，但不符合DRF序列化器的规范写法，可能引发潜在的上下文问题。

解决方法 #

1. 修正extra_kwargs的位置 #

将extra_kwargs移动到class Meta内部：

class RegisterSerializer(serializers.ModelSerializer):
    password = serializers.CharField(
        write_only=True,
        max_length=68,
        min_length=8,
        error_messages={"min_length": f"Password must be longer than {MIN_LENGTH}characters"},
        required=True,
        validators=[validate_password]
    )
    password2 = serializers.CharField(
        write_only=True,
        max_length=68,
        min_length=8,
        error_messages={"min_length": f"Password must be longer than {MIN_LENGTH}characters"},
        required=True
    )

    class Meta:
        model = User
        fields = ('username','phone','password','password2')
        # 修正：extra_kwargs移至Meta内部
        extra_kwargs = {
            'password': {'write_only': True},
            'password2': {'write_only': True}
        }
    
    # 剩余方法保持不变（后续修正create方法）

2. 规范create方法的参数使用 #

将self.validated_data替换为方法传入的validated_data参数：

def create(self, validated_data):
    user = User.objects.create(
        phone=validated_data['phone'],
        username=validated_data['username'],
    )
    user.set_password(validated_data['password'])
    user.save()
    return user 

3. 可选优化（避免重复配置） #

由于已经在extra_kwargs中设置了write_only=True，可以移除字段显式定义中的write_only=True，减少重复配置：

password = serializers.CharField(
    max_length=68,
    min_length=8,
    error_messages={"min_length": f"Password must be longer than {MIN_LENGTH}characters"},
    required=True,
    validators=[validate_password]
)
password2 = serializers.CharField(
    max_length=68,
    min_length=8,
    error_messages={"min_length": f"Password must be longer than {MIN_LENGTH}characters"},
    required=True
)

验证 #

修改完成后重新测试注册接口，RecursionError应被解决，接口可正常创建用户并返回序列化后的用户数据（password字段不会出现在响应中）。

内容的提问来源于stack exchange，提问作者siaka karl