python - 类型错误 : Cannot create a consistent method resolution in django

Question

我正在通过“Django 3 by example”这本书学习 django，现在我正在尝试构建一个电子学习平台。但是，我的 views.py 文件中出现了一个奇怪的错误。
这是我的意见文件:

from django.views.generic.list import ListView
from django.urls import reverse_lazy
from django.views.generic.edit import CreateView, UpdateView, DeleteView
from django.contrib.auth.mixins import LoginRequiredMixin, PermissionRequiredMixin
from .models import Course


class ManageCourseListView(ListView):
    model = Course
    template_name = 'educa/manage/educa/list.html'
    permission_required = 'educa.view_course'

    def get_queryset(self):
        qs = super().get_queryset()
        return qs.filter(owner=self.request.user)


class OwnerMixin(object):
    def get_queryset(self):
        qs = super().get_queryset()
        return qs.filter(owner=self.request.owner)


class OwnerEditMixin(object):
    def form_valid(self, form):
        form.instance.onwer = self.request.user
        return super().form_valid(form)


class OwnerCourseMixin(object, LoginRequiredMixin, PermissionRequiredMixin):
    model = Course
    fields = ['subject', 'title', 'slug', 'overview']
    success_url = reverse_lazy('manage_course_list')


class OwnerCourseEditMixin(OwnerCourseMixin, OwnerEditMixin):
    template_name = 'educa/manage/course/list.html'


class CourseCreateView(OwnerEditMixin, CreateView):
    permission_required = 'educa.add_course'


class CourseUpdateView(OwnerCourseEditMixin, UpdateView):
    permission_required = 'educa.change_course'


class CourseDeleteView(OwnerCourseMixin, DeleteView):
    template_name = 'educa/manage/course/delete.html'
    permission_required = 'educa.delete_course'

错误在第 30 行。
这是完整的错误消息:

Exception in thread django-main-thread:
Traceback (most recent call last):
  File "C:\Users\Padma Jain\AppData\Local\Programs\Python\Python38\lib\threading.py", line 932, in _bootstrap_inner
    self.run()
  File "C:\Users\Padma Jain\AppData\Local\Programs\Python\Python38\lib\threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\utils\autoreload.py", line 53, in wrapper
    fn(*args, **kwargs)
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\core\management\commands\runserver.py", line 118, in inner_run
    self.check(display_num_errors=True)
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\core\management\base.py", line 392, in check
    all_issues = checks.run_checks(
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\core\checks\registry.py", line 70, in run_checks
    new_errors = check(app_configs=app_configs, databases=databases)
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\core\checks\urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\core\checks\urls.py", line 23, in check_resolver
    return check_method()
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\urls\resolvers.py", line 408, in check
    for pattern in self.url_patterns:
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\utils\functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\urls\resolvers.py", line 589, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\utils\functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\urls\resolvers.py", line 582, in urlconf_module
    return import_module(self.urlconf_name)
  File "C:\Users\Padma Jain\AppData\Local\Programs\Python\Python38\lib\importlib\__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "C:\Users\Padma Jain\Desktop\django\educa\elearn\elearn\urls.py", line 24, in <module>
    path('course/',include('educa.urls')),
  File "C:\Users\Padma Jain\Desktop\django\educa\venv\lib\site-packages\django\urls\conf.py", line 34, in include
    urlconf_module = import_module(urlconf_module)
  File "C:\Users\Padma Jain\AppData\Local\Programs\Python\Python38\lib\importlib\__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "C:\Users\Padma Jain\Desktop\django\educa\elearn\educa\urls.py", line 2, in <module>
    from .views import *
  File "C:\Users\Padma Jain\Desktop\django\educa\elearn\educa\views.py", line 30, in <module>
    class OwnerCourseMixin(object, LoginRequiredMixin, PermissionRequiredMixin):
TypeError: Cannot create a consistent method resolution
order (MRO) for bases object, LoginRequiredMixin, PermissionRequiredMixin

如果需要，这里是 educa 应用程序的 urls.py 文件:

from django.urls import path
from .views import *

urlpatterns = [
    path('mine/',ManageCourseListView.as_view(),name='manage_course_list'),
    path('create/',CourseCreateView.as_view(),name='course_create'),
    path('<pk>/edit/',CourseUpdateView.as_view(),name='course_edit'),
    path('<pk>/delete/',CourseDeleteView.as_view(),name='course_delete'),
]

这是我第一次构建这么大的应用程序。有人可以告诉我哪里错了吗？
编辑 :
我通过编辑 views.py 文件的第 30 行解决了这个问题:

class OwnerCourseMixin(object, LoginRequiredMixin, PermissionRequiredMixin):
   ....

对此:

class OwnerCourseMixin(OwnerMixin, LoginRequiredMixin, PermissionRequiredMixin):
    ....

Answer 1

在 Python 中，每个类都继承自一个名为 object 的内置基本类。 .
您的 OwnerCourseMixin 继承自 object 和 其他一些类(class)。因为其他类，在这种情况下，LoginRequiredMixin和 PermissionRequiredMixin , 已经继承自 object ，Python 现在无法确定首先查找哪个类。
您不需要从 object 继承这里。

class OwnerCourseMixin(LoginRequiredMixin, PermissionRequiredMixin):
    model = Course
    fields = ['subject', 'title', 'slug', 'overview']
    success_url = reverse_lazy('manage_course_list')

那应该工作。