字典更新序列元素＃0具有长度15; 2是必需的

Question

我正在将我的python/django应用程序从1.6.5升级到1.7。我无法解决以下错误：字典更新序列元素＃0的长度为15; 2需要

这里是回溯输出：

Request Method: GET 
Request URL: http://127.0.0.1:8000/dashboard/ 

Django Version: 1.7 
Python Version: 2.7.5 
Installed Applications: 
('django.contrib.admin', 
'django.contrib.auth', 
'django.contrib.contenttypes', 
'django.contrib.sessions', 
'django.contrib.messages', 
'django.contrib.staticfiles', 
'django.contrib.sites', 
'django.contrib.humanize', 
'bootstrap3', 
'ajax_select', 
'appconf', 
'versiontools', 
'compressor', 
'googlecharts', 
'django_extensions', 
'mandala', 
'locations', 
'statistics', 
'alarms', 
'accounts', 
'assets') 
Installed Middleware: 
('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/CLDSupportSystems/mandala-system/mandala_env_django_1.7/lib/python2.7/sit-packages/django/core/handlers/base.py" in get_response 
111.      response = wrapped_callback(request, *callback_args, **callback_kwargs) 
File "/Users/CLDSupportSystems/mandala-system/mandala_env_django_1.7/lib/python2.7/site-packages/django/contrib/auth/decorators.py" in _wrapped_view 
    22.     return view_func(request, *args, **kwargs) 
File "/Users/CLDSupportSystems/mandala-system/mandala_env_django_1.7/mandala/mandala/views.py" in dashboard 
    117.   return render_to_response('dashboard/dashboard.html', variables,context_instance=RequestContext(request)) 
File "/Users/CLDSupportSystems/mandala-system/mandala_env_django_1.7/lib/python2.7/site-packages/django/shortcuts.py" in render_to_response 
    23.  return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs) 
File "/Users/CLDSupportSystems/mandala-system/mandala_env_django_1.7/lib/python2.7/site-packages/django/template/loader.py" in render_to_string 
    177.  with context_instance.push(dictionary): 
File "/Users/CLDSupportSystems/mandala-system/mandala_env_django_1.7/lib/python2.7/site-packages/django/template/context.py" in push 
    54.   return ContextDict(self, *args, **kwargs) 
File "/Users/CLDSupportSystems/mandala-system/mandala_env_django_1.7/lib/python2.7/site-packages/django/template/context.py" in __init__ 
    19.   super(ContextDict, self).__init__(*args, **kwargs) 

Exception Type: ValueError at /dashboard/ 
Exception Value: dictionary update sequence element #0 has length 15; 2 is required 

该错误是在下面的行抛出：

return render_to_response('dashboard/dashboard.html', variables,context_instance=RequestContext(request)) 

下面是变量的定义：

variables = RequestContext(request, { 
    'fresh_locations': fresh_data_locations, 
    'webalert_locations': webalert_locations, 
    'locations_reporting': reporting_locations, 
    'locations_not_reporting': locations_not_reporting, 
    'inalarm_count': inalarm_count, 
    'inalarm_stores': inalarm_stores_qs, 
    'workspace_count': workspace_count, 
    'user_profile': user_profile, 
}) 

任何人都可以将我指向正确的方向吗？

Answer 1

render_to_response()的第二个参数必须是字典。您正在传递RequestContext()。

取出RequestContext()对象，使variables只是的字典：

variables = { 
    'fresh_locations': fresh_data_locations, 
    'webalert_locations': webalert_locations, 
    'locations_reporting': reporting_locations, 
    'locations_not_reporting': locations_not_reporting, 
    'inalarm_count': inalarm_count, 
    'inalarm_stores': inalarm_stores_qs, 
    'workspace_count': workspace_count, 
    'user_profile': user_profile, 
} 

Answer 2

这是因为render_to_response（）这个也呈现（）的快捷方式将上下文变量自动应用的RequestContext（你的变量DIR） 。它确实是一个错字，但为什么它在你问之前就起作用了？

它可能会达到1.6，但django.template.context中的实现RequestContext已在1.7中更改。它被分解为更多的面向对象和优化，使其更高效。历史在这里，我认为这是

https://github.com/django/django/commits/master/django/template/context.py

这次提交特别优化的RequestContext：

https://github.com/django/django/commit/8d473b2c54035cbcd3aacef0cb83a9769cd05ad3

下面是如何重新产生错误：

>>> from django.template import RequestContext 
>>> from django.test.client import RequestFactory 
>>> request_factory = RequestFactory() 
>>> request = request_factory.get('www.google.com') 
>>> fresh_data_locations, webalert_locations, reporting_locations, locations_not_reporting, inalarm_count, inalarm_stores_qs, workspace_count, user_profile = '', '', '', '', '', '', '', '' 
>>> variables = RequestContext(request, { 
...  'fresh_locations': fresh_data_locations, 
...  'webalert_locations': webalert_locations, 
...  'locations_reporting': reporting_locations, 
...  'locations_not_reporting': locations_not_reporting, 
...  'inalarm_count': inalarm_count, 
...  'inalarm_stores': inalarm_stores_qs, 
...  'workspace_count': workspace_count, 
...  'user_profile': user_profile, 
... }) 
>>> variables 
[{'False': False, 'None': None, 'True': True}, {'workspace_count': '', 'locations_not_reporting': '', 'fresh_locations': '', 'inalarm_stores': '', 'locations_reporting': '', 'webalert_locations': '', 'user_profile': '', 'inalarm_count': ''}, {u'csrf_token': <django.utils.functional.__proxy__ object at 0x10439fcd0>, u'sql_queries': [], 'perms': <django.contrib.auth.context_processors.PermWrapper object at 0x10439fe50>, 'messages': [], u'request': <WSGIRequest 
path:/www.google.com, 
GET:<QueryDict: {}>, 
POST:<QueryDict: {}>, 
COOKIES:{}, 
META:{u'HTTP_COOKIE': u'', 
u'PATH_INFO': u'www.google.com', 
u'QUERY_STRING': '', 
u'REMOTE_ADDR': '127.0.0.1', 
u'REQUEST_METHOD': 'GET', 
u'SCRIPT_NAME': u'', 
u'SERVER_NAME': 'testserver', 
u'SERVER_PORT': '80', 
u'SERVER_PROTOCOL': 'HTTP/1.1', 
u'wsgi.errors': <_io.BytesIO object at 0x1042fce30>, 
u'wsgi.input': <django.test.client.FakePayload object at 0x104391550>, 
u'wsgi.multiprocess': True, 
u'wsgi.multithread': False, 
u'wsgi.run_once': False, 
u'wsgi.url_scheme': 'http', 
u'wsgi.version': (1, 0)}>, 'api_header': {'content-type': 'application/json', 'Authorization': 'YmFrZXItYXBpOlVuaW9uMTIz'}, u'STATIC_URL': '/static/', u'LANGUAGES': (('en', 'English'),), 'api_address': 'http://69.164.69.214/BakerPublic/api', 'user': <django.contrib.auth.models.AnonymousUser object at 0x10439fe10>, u'LANGUAGE_CODE': u'en-us', u'debug': True, 'DEFAULT_MESSAGE_LEVELS': {'DEBUG': 10, 'INFO': 20, 'WARNING': 30, 'SUCCESS': 25, 'ERROR': 40}, u'LANGUAGE_BIDI': False, u'MEDIA_URL': '/media/'}] 
>>> type(variables) 
<class 'django.template.context.RequestContext'> 
>>> dict(variables) 
Traceback (most recent call last): 
    File "<console>", line 1, in <module> 
ValueError: dictionary update sequence element #0 has length 15; 2 is required 

因此，与django 1.6 dir（）函数返回没有错误，但与1.7实现失败。只有其中一件事情可以在1.7之前说出巧合。

从django.views.generic使用基于类的视图时，很多东西都是为您完成的。如果您查看TemplateView，您会看到它从TemplateResponseMixin继承了render_to_response方法，该方法使用TemplateResponse完成所有这些工作。同时检查一下ContextMixin，它有get_context_data方法。我认为将上下文数据传递给模板的最简洁的方法。更多关于通用/基于类的视图here。