AttributeError: at / 'User‘对象没有属性'standard’

Question

serializers.py：

from django.forms import widgets
from rest_framework import serializers
from .models import Classname, Sectionname, Teachername, Attendancename
from django.contrib.auth.models import User


class UserSerializer(serializers.HyperlinkedModelSerializer):
    standard = serializers.PrimaryKeyRelatedField(many=True, queryset=Classname.objects.all())
    section = serializers.PrimaryKeyRelatedField(many=True, queryset=Sectionname.objects.all())
    teacher = serializers.PrimaryKeyRelatedField(many=True, queryset=Teachername.objects.all())
    attend = serializers.PrimaryKeyRelatedField(many=True, queryset=Attendancename.objects.all())

    class Meta:
        model = User
        fields = ('id', 'username', 'standard', 'section', 'teacher', 'attend',)
#when I'm attempting to add 'standard' field it raises above exception.

class ClassSerializer(serializers.ModelSerializer):
    class Meta:
        model = Classname
        fields = ('id', 'class_name',)

class SectionSerializer(serializers.ModelSerializer):
    class Meta:
        model = Sectionname
        fields = ('id', 'class_name', 'section_name')

class TeacherSerializer(serializers.ModelSerializer):
    class Meta:
        model = Teachername
        fields = ('id', 'classname', 'secname', 'teachname')

class AttendanceSerializer(serializers.ModelSerializer):
    class Meta:
        model = Attendancename
        fields = ('id', 'teacher_name', 'date', 'intime', 'outtime')

我的回溯：

Environment:


Request Method: GET
Request URL: http://127.0.0.1:8000/stu/users/

Django Version: 1.8.3
Python Version: 3.4.3
Installed Applications:
('django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'rest_framework',
 'student')
Installed Middleware:
('django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.middleware.security.SecurityMiddleware')


Traceback:
File "C:\Users\User\demo\venv\lib\site-packages\django\core\handlers\base.py" in get_response
  132.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\User\demo\venv\lib\site-packages\django\views\decorators\csrf.py" in wrapped_view
  58.         return view_func(*args, **kwargs)
File "C:\Users\User\demo\venv\lib\site-packages\django\views\generic\base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\views.py" in dispatch
  456.             response = self.handle_exception(exc)
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\views.py" in dispatch
  453.             response = handler(request, *args, **kwargs)
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\generics.py" in get
  199.         return self.list(request, *args, **kwargs)
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\mixins.py" in list
  47.         return Response(serializer.data)
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\serializers.py" in data
  622.         ret = super(ListSerializer, self).data
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\serializers.py" in data
  217.                 self._data = self.to_representation(self.instance)
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\serializers.py" in to_representation
  572.             self.child.to_representation(item) for item in iterable
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\serializers.py" in <listcomp>
  572.             self.child.to_representation(item) for item in iterable
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\serializers.py" in to_representation
  430.                 attribute = field.get_attribute(instance)
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\relations.py" in get_attribute
  367.         relationship = get_attribute(instance, self.source_attrs)
File "C:\Users\User\demo\venv\lib\site-packages\rest_framework\fields.py" in get_attribute
  71.                 instance = getattr(instance, attr)

Exception Type: AttributeError at /stu/users/
Exception Value: 'User' object has no attribute 'standard'

我正在学习DRF的教程。我想像上面那样在'UserSerializer'中添加所有与主键引用相关的模型，但它引发了上述异常。

因为我有四个模型，所以我在'UserSerializer'类中获取了四个单独的变量，并尝试将其显示到User API中。

我是不是做错了什么？请为我提供您的建议...

提前感谢....

Answer 1

默认的User模型中没有定义属性standard。

在Django的User 模型中定义的字段为：

1. username
2. first_name
3. last_name
4. email
5. password
6. groups
7. user_permissions
8. is_staff
9. is_active
10. is_superuser
11. last_login
12. date_joined

由于在standard User 模型中未定义字段，因此您的代码无法正常工作。

相反，您可以扩展User模型，然后向该自定义用户模型添加额外的standard字段。

from django.contrib.auth.models import AbstractUser
from django.db import models

class CustomUser(AbstractUser):

    standard = models.CharField() # add the 'standard' field

然后在您的设置中，您需要将其指定为用户模型。

AUTH_USER_MODEL = 'my_app.models.CustomUser'

您可以使用get_user_model()函数，它将返回当前活动的用户模型，即CustomUser模型。

Answer 2

我也遇到了同样的问题。在类名模型上创建ForeignKey时需要提供的related_name然后在序列化程序上创建反向关系时，应该使用related_name作为序列化程序上的变量的名称。例如：

class Classname(models.Model):
    user = ForeignKey(User, related_name='standard')

class UserSerializer(serializers.HyperlinkedModelSerializer):
    standard = serializers.PrimaryKeyRelatedField(many=True, queryset=Classname.objects.all())

    class Meta:
        model = User
        fields = ('id', 'username', 'standard', 'section', 'teacher', 'attend',)

Here是相关文档。