[英]Django: can't iterate over and access a simple queryset
對於我的API,我必須找出用戶可以訪問哪些項目,然后將其返回。 我嘗試這樣做:
def get_queryset(self):
user = self.request.user
allow_all = user.is_superuser or user.is_staff or settings.API_UNSAFE
if self.action == 'list' and not allow_all:
projects = Project.objects.all()
user_projects = Project.objects.none()
for project in projects:
permission = Permission.objects.filter(user=user.user, table_name='Project', fk=project.id)
if permission.count() > 0:
user_projects = user_projects | project
return user_projects
return Project.objects.all()
結果是:
'Project' object is not iterable
所以我用values()
代替了all()
。 但是,當您使用.values
就無法再通過查詢集連接實例。 這意味着我必須查詢同一項目兩次,從而導致這種駭人聽聞的方法:
projects = Project.objects.values()
user_projects = Project.objects.none()
for project in projects:
permission = Permission.objects.filter(user=user.user, table_name='Project', fk=project['id'])
if permission.count() > 0:
# Wanted to use .get() here, but that threw the same error
user_project = Project.objects.filter(id=project['id'])
user_projects |= user_project
return user_projects
當然有更好的方法,我在做什么錯?
堆棧跟蹤:
Environment:
Request Method: GET
Request URL: http://localhost:8000/api/projects/
Django Version: 2.0.6
Python Version: 3.7.0
Installed Applications:
['apps.api',
'rest_framework',
'apps.dashboard',
'apps.login',
'apps.base',
'sass_processor',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'django_seed',
'rest_framework.authtoken']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware']
Traceback:
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/django/core/handlers/exception.py" in inner
35. response = get_response(request)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/django/core/handlers/base.py" in _get_response
128. response = self.process_exception_by_middleware(e, request)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/django/core/handlers/base.py" in _get_response
126. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/django/views/decorators/csrf.py" in wrapped_view
54. return view_func(*args, **kwargs)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/rest_framework/viewsets.py" in view
95. return self.dispatch(request, *args, **kwargs)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/rest_framework/views.py" in dispatch
494. response = self.handle_exception(exc)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/rest_framework/views.py" in handle_exception
454. self.raise_uncaught_exception(exc)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/rest_framework/views.py" in dispatch
491. response = handler(request, *args, **kwargs)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/rest_framework/mixins.py" in list
48. return Response(serializer.data)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/rest_framework/serializers.py" in data
742. ret = super(ListSerializer, self).data
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/rest_framework/serializers.py" in data
262. self._data = self.to_representation(self.instance)
File "/Users/Ruben/Documents/Projects/BIM_Github/bim-data-manager/venv/lib/python3.7/site-packages/rest_framework/serializers.py" in to_representation
660. self.child.to_representation(item) for item in iterable
Exception Type: TypeError at /api/projects/
Exception Value: 'Project' object is not iterable
該錯誤與訪問項目ID無關。
|
的結果 在空查詢集和實例之間的是實例。 因此,這意味着當您的權限存在時,您的user_projects
變量將成為一個實例; 然后,隨后的序列化程序由於期望查詢集而失敗。
您已經有一個更好的方法可以在單個查詢中執行此操作,但是如果您確實想要建立這樣的列表,則可以作為參考,更好的方法是累積ID,然后在一次查詢中將它們全部獲取; 或者,只需將實例附加到列表中。
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