Django应用程序出现错误：”TypeError: ‘dict_keys’对象不可订阅”

huangapple
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英文:

Django app getting the error "TypeError: 'dict_keys' object is not subscriptable"

问题

以下是代码的翻译部分：

  1. 这是视图：
  3. class UserViewSet(viewsets.ViewSet):
  4.   def list(self, request):
  5.     queryset = User.objects.all()
  6.     serializer = UserSerializer(queryset, many=True)
  7.     return Response(serializer.data)
  8.   
  9.   def retrieve(self, request, pk=None):
  10.     queryset = User.objects.all()
  11.     user = get_object_or_404(queryset, pk=pk)
  12.     serializer = UserSerializer(user)
  13.     return Response(serializer.data)

URLs：

  1. from django.urls import path
  2. from .views import *
  3. from rest_framework import routers
  5. userl = UserViewSet.as_view({'get': 'list'})
  6. userd = UserViewSet.as_view({'get': 'retrieve'})
  8. router = routers.SimpleRouter()
  9. router.register('users', UserViewSet, basename='user')
  11. urlpatterns = [
  12.   path('users/', userl, name='user-list'),
  13.   path('users/<int:pk>/', userd, name='user-detail'),
  14.   path('register', RegisterUserAPIView.as_view()),
  15.   path('login/', LoginAPIView.as_view()),
  16.   path('logout', LogoutAPIView.as_view()),
  17.   path('products', ProductsViewSet.as_view({'get': 'list'})),
  18. ]

跟踪信息：

  1. File "C:\Users\User\Desktop\erkin2\venv\lib\site-packages\routers\router.py", line 27, in db_for_read
  2.     return settings.DATABASES.keys()[0]
  3. TypeError: 'dict_keys' object is not subscriptable
  5. 我尝试使用`keys()`，但然后它说：
  7. > 函数没有属性keys()。
英文:

Here is the views:

  1. class UserViewSet(viewsets.ViewSet):
  2.   def list(self, request):
  3.     queryset = User.objects.all()
  4.     serializer = UserSerializer(queryset, many=True)
  5.     return Response(serializer.data)
  6.   
  7.   def retrieve(self, request, pk=None):
  8.     queryset = User.objects.all()
  9.     user = get_object_or_404(queryset, pk=pk)
  10.     serializer = UserSerializer(user)
  11.     return Response(serializer.data)

urls:

  1. from django.urls import path
  2. from .views import *
  3. from rest_framework import routers
  5. userl = UserViewSet.as_view({&#39;get&#39;: &#39;list&#39;})
  6. userd = UserViewSet.as_view({&#39;get&#39;: &#39;retrieve&#39;})
  8. router = routers.SimpleRouter()
  9. router.register(r&#39;users&#39;, UserViewSet, basename=&#39;user&#39;)
  11. urlpatterns = [
  12.   path(&#39;users/&#39;, userl, name=&#39;user-list&#39;),
  13.   path(&#39;users/&lt;int:pk&gt;/&#39;, userd, name=&#39;user-detail&#39;),
  14.   path(&#39;register&#39;,RegisterUserAPIView.as_view()),
  15.   path(&#39;login/&#39;, LoginAPIView.as_view()),
  16.   path(&#39;logout&#39;, LogoutAPIView.as_view()),
  17.   path(&#39;products&#39;, ProductsViewSet.as_view({&#39;get&#39;: &#39;list&#39;})),
  19. ]&#39;login/&#39;, LoginAPIView.as_view()),
  20.   path(&#39;logout&#39;, LogoutAPIView.as_view()),
  21.   path(&#39;products&#39;, ProductsViewSet.as_view({&#39;get&#39;: &#39;list&#39;})),
  23. ]

Traceback:

  1.   File &quot;C:\Users\User\Desktop\erkin2\venv\lib\site-packages\routers\router.py&quot;, line 27, in db_for_read
  2.     return settings.DATABASES.keys()[0]
  3. TypeError: &#39;dict_keys&#39; object is not subscriptable

I've tried using keys() but then it says:

> function has no attribute keys().

答案1

得分: 1

  1. 明显并且也许逆直觉的是，字典的 `keys()` 方法并不返回一个键列表。让我们检查一下：
  2. ```python
  3. d = {'a': 1, 'b': 2}
  5. print(d.keys())
  6. >>> dict_keys(['a', 'b'])
  8. print(type(d.keys()))
  9. >>> <class 'dict_keys'>
  11. d.keys()[0]
  12. >>> TypeError: 'dict_keys' 对象不可索引

这并不总是如此。在Python 2中，keys() 方法确实返回一个列表。参见这个旧问题。

要获取键的实际列表，您可以在字典上调用 list()：

  1. print(list(d))
  2. >>> ['a', 'b']

然后索引将按预期工作：

  1. print(list(d)[0])
  2. >>> a

因此，您可能希望将行 return settings.DATABASES.keys()[0] 更改为：

  1. return list(settings.DATABASES)[0]
  2. <details>
  3. <summary>英文:</summary>
  5. Apparently and perhaps counter-intuitively, the `keys()` method for dictionaries does not return a list of keys. Let&#39;s check:
  6. ```python
  7. d = {&#39;a&#39;: 1, &#39;b&#39;: 2}
  9. print(d.keys())
  10. &gt;&gt;&gt; dict_keys([&#39;a&#39;, &#39;b&#39;])
  12. print(type(d.keys()))
  13. &gt;&gt;&gt; &lt;class &#39;dict_keys&#39;&gt;
  15. d.keys()[0]
  16. &gt;&gt;&gt; TypeError: &#39;dict_keys&#39; object is not subscriptable

This was not always so. In Python 2, the keys() method did return a list. See this old question.

To get an actual list of the keys, you can call list() on the dictionary:

  1. print(list(d))
  2. &gt;&gt;&gt; [&#39;a&#39;, &#39;b&#39;]

Then indexing works as expected:

  1. print(list(d)[0])
  2. &gt;&gt;&gt; a

So you may want to change the line return settings.DATABASES.keys()[0] to this:

  1. return list(settings.DATABASES)[0]

huangapple
  • 本文由 发表于 2023年4月7日 04:14:40
  • 转载请务必保留本文链接：https://go.coder-hub.com/75953425.html
  • django-rest-framework
  • python
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