异常值：类型对象“Discipline”没有属性“description”

Question

因此，我正在使用Django Rest框架构建我的第一个Django项目，我有以下3个模型：

class Student(models.Model):
    user = models.OneToOneField(User, unique=True)
    ra = models.IntegerField()

class Discipline (models.Model):
    description = models.CharField(max_length=150)
    professor = models.ForeignKey(Professor, related_name='disciplines')
    learners = models.ManyToManyField('students.Student', through='enrollments.enrollment', related_name='disciplines')

class Enrollment (models.Model):
    discipline = models.ForeignKey('disciplines.Discipline')
    student = models.ForeignKey(Student)
    enroll_date = models.DateField(auto_now_add=True)

对于这些模型，我有以下序列化程序：

^{pr2}$

在我的视图.py对于我的学生应用程序，我有以下代码：

class StudentList (generics.ListCreateAPIView):
    model = Student
    serializer_class = StudentSerializer
    permission_classes = [
        permissions.IsAuthenticatedOrReadOnly,
    ]


class StudentDetail (generics.RetrieveAPIView):
    model = Student
    serializer_class = StudentSerializer


class StudentDisciplineList (generics.ListAPIView):
    model = Enrollment
    serializer_class = EnrolledDisciplinesSerializer

    def get_queryset(self):
        queryset = super(StudentDisciplineList, self).get_queryset()
        return queryset.filter(student__pk=self.kwargs.get('pk'))


class StudentActivitiesList (generics.ListAPIView):
    model = Activity
    serializer_class = ActivitiesSerializer

    def get_queryset(self):
        queryset = super(StudentActivitiesList, self).get_queryset()
        return queryset.filter(student__pk=self.kwargs.get('pk'))

创建视图后，我将以下内容添加到网址.py我的学生应用程序中的文件：

url_patterns = [
    '',
    url(r'^/(?P<pk>\d+)/disciplines$', StudentDisciplineList.as_view(), name='studentdiscipline-list'),
    url(r'^/(?P<pk>\d+)/activities$', StudentActivitiesList.as_view(), name='studentactivities-list'),
    url(r'^/(?P<pk>\d+)$', StudentDetail.as_view(), name='student-detail'),
    url(r'^$', StudentList.as_view(), name='student-list'),
]

然后我把这个加到我的主菜单上网址.py文件：

import students.urls

urlpatterns = [
    url(r'^admin/', include(admin.site.urls)),
    url(r'^students/', include(students.urls)),
]

完成此操作后，我前往http://127.0.0.1:8000/students并得到以下信息：

File "C:\Users\Douglas\tg_project\enrollments\serializers.py" in EnrolledDisciplinesSerializer


9.     description = serializers.ReadOnlyField(source=Discipline.description)

Exception Type: AttributeError at /admin
Exception Value: type object 'Discipline' has no attribute 'description'

我已经在Google和StackOverflow上搜索过了，但是我找不到帮助我的东西。我还查看了整个代码，看看是否有任何输入错误，但似乎一切正常。在

我真的很感谢你帮我解决这个问题。在

Answer 1

source应该是一个包含要从Enrollment实例获取的属性的字符串。所以在你的EnrolledDisciplinesSerializer中，对于description，你需要{}。discipline（小写）是访问该注册的规程的属性名，description获取该规程实例描述的名称。其他领域也一样。在

Django使用元类来构造模型。这样，在模型中定义的字段不会作为类的属性结束。这意味着Discipline类没有属性Discipline.description。只有Discipline的实例具有description属性。在