尝试获取字段值时出现 AttributeError

Question

**尝试从一个端点创建两个对象（没有嵌套序列化器）。registration_no当尝试获取序列化器上的字段值时，我收到错误 ERROR: AttributeError at /migratestudent Got AttributeError StudentDataMigrateSerializer。序列化程序字段可能命名不正确，并且与Student实例上的任何属性或键不匹配。原始异常文本是：'Student' object has no attribute 'registration_no'。

class Student(models.Model):
    name = models.CharField(max_length=300)
    sex  = models.CharField(choices=SEX_CHOICES,max_length=255, null=True)
    Category = models.CharField(max_length=100, null=True)

    def __str__(self):
        return self.name


class Registration(models.Model):
    registration_no = models.CharField(max_length=255, unique=True)
    student = models.OneToOneField(Student, 
    on_delete= models.CASCADE, related_name='registration')

    def __str__(self):
    return self.registration_no

class StudentDataMigrateSerializer(serializers.Serializer):

    name = serializers.CharField()
    sex = serializers.CharField()
    registration_no = serializers.CharField()
    #registration_no = serializers.CharField()


    def create(self,validated_data):
        name = validated_data.pop('name')
        sex = validated_data.pop('sex')
        registration_no= validated_data.pop('registration_no')
        #registration_no = validated_data.pop('registration_no')
        #check for existence of registration number

        #Student.objects.CheckRegistration(name, '4')

        try:
            regn = Registration.objects.get('registration_no')
        except:
            student = Student.objects.create(name=name, sex=sex)
            registration = Registration.objects.create(
                    registration_no=registration_no,
                    student=student)

        return student

class StudentDataMigrateCreateAPIVIew(ListCreateAPIView):
    serializer_class= StudentDataMigrateSerializer

    def get_queryset(self):
        student = Student.objects.all()
        return student

Answer 1

您在序列化器上定义这些字段：

class StudentDataMigrateSerializer(serializers.Serializer):
    name = serializers.CharField()
    sex = serializers.CharField()
    registration_no = serializers.CharField()

并在您的方法中返回student对象create：

    def create(self,validated_data):
        ...
        return student

当您向此端点发出发布请求时，StudentDataMigrateCreateAPIVIew正在使用请求数据创建序列化程序 ( StudentDataMigrateSerializer) 并验证它。如果验证通过，它将调用create序列化器的方法。到现在为止一切都还好。创建实例后，视图还必须返回响应。所以它返回data序列化器的属性。

此时，serializer.data实际上是您在方法中返回的学生对象的表示create。您的序列化程序尝试根据其中定义的字段返回表示形式。

这些是您在序列化上定义的字段：name, sex, registration_no。但是Student模型，因此student对象没有registration_no字段。因此，当您的序列化程序尝试在对象上获取此字段时，它会失败student。

您可以创建registration_no字段write_only，使其不会在响应中返回。

class StudentDataMigrateSerializer(serializers.Serializer):
    name = serializers.CharField()
    sex = serializers.CharField()
    registration_no = serializers.CharField(write_only=True)