在django表单中使用reverse（） [英] Using reverse() in django forms

问题描述

我正在尝试使用django的 reverse（）功能定义django表单为我的自定义小部件，但我收到一个错误：

 不正确的配置
包含的urlconf网址没有
  

这里是代码：

pre> class WorkForm（forms.Form）：
＃...
category = forms.ChoiceField（
required = True，
label = _（'Category'），
help_text = _（'为你的工作选择最合适的类别'）
）
subcategory = forms.ChoiceField（
widget = DependantChoiceWidget （
default_value = _（'Select category first'），
data_source_url = reverse（'works-json-categories'），
＃data_source_url ='' b $ b depends_on ='category_id'
），
requ ired = True，
label = _（'SubCategory'），
help_text = _（'哪个子类适合你的工作最好'）
）


我很确定，我的'works.urls'配置正确，因为所有其他页面都按预期工作。

是否有原因，为什么我不能在表单定义中使用 reverse（）？与代码运行有关吗？有没有办法解决这个问题，或者唯一的选择是硬编码URL？

这是完整的错误转储：

 环境：
 
请求方法：GET 
请求URL：http://127.0.0.1:8000/works/add?category = 1& subcategory = 1 
 
 Django版本：1.4 pre-alpha 
 Python版本：2.7.1 
安装的应用程序：
 ['django.contrib.auth' ，
'django.contrib.contenttypes'，
'django.contrib.sessions'，
'django.contrib.sites'，
'django.contrib.messages'，
'django.contrib.staticfiles'，
'django.contrib.admin'，
'django.contrib.admindocs'，
'social_auth'，
'sorl。 
'help'，
'users'，
'works'，
'debug_toolbar'] 
安装的中间件：
（'django。 middleware.common.CommonMiddleware'，
'django.contrib.sessions.middleware.SessionMiddleware'，
'django.middleware.transaction.TransactionMid dleware'，
'django.middleware.csrf.CsrfViewMiddleware'，
'django.contrib.auth.middleware.AuthenticationMiddleware'，
'django.contrib.messages.middleware.MessageMiddleware'，
'debug_toolbar.middleware.DebugToolbarMiddleware'）
 
 
追溯：
文件/usr/local/lib/python2.7/dist-packages/django/core/ get_response中的处理程序/ base.py
 89. response = middleware_method（request）
文件/usr/local/lib/python2.7/dist-packages/django/middleware/common.py process_request 
 67.如果（不是_is_valid_path（request.path_info，urlconf）和
文件/usr/local/lib/python2.7/dist-packages/django/middleware/common.py在_is_valid_path 
 164. urlresolvers.resolve（path，urlconf）
解析
 416中的/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py文件。return get_resolver（urlconf）.resolve（path）
文件/usr/local/lib/python2.7/dist-packages/django/core/urlr esolvers.py解析
 298.对于self.url_patterns中的模式：
文件/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py在url_patterns 
 328. patterns = getattr（self.urlconf_module，urlpatterns，self.urlconf_module）
文件/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py in urlconf_module 
 323. self._urlconf_module = import_module（self.urlconf_name）
 import_module中的/usr/local/lib/python2.7/dist-packages/django/utils/importlib.py文件
 35. __import __（name）
< module>中的文件/var/www/megenius/trunk/urls.py 
 27. url（r'^ works /'，include（'works.urls'）），
文件/usr/local/lib/python2.7/dist-packages/django/conf/ urls / __ init__.pyin include 
 24. urlconf_module = import_module（urlconf_module）
文件/usr/local/lib/python2.7/dist-packages/django/utils/importlib.py在import_module 
 35. __import __（name）
< module>中的文件/var/www/megenius/trunk/works/urls.py 
 2.从works.views import * 
文件/var/www/megenius/trunk/works/views.py在< module> 
 9.从works.forms导入WorkForm 
< module>中的文件/var/www/megenius/trunk/works/forms.py 
 10. WorkForm（forms.Form）：
 WorkForm中的文件/var/www/megenius/trunk/works/forms.py
 31. data_source_url = reverse（'works- json-categories'），
文件/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py反向
 473.（prefix，resolver.reverse（查看，* args，** kwargs）））
文件/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py反向
 360.可能性= self.reverse_dict.getlist（lookup_view）
文件/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.pyin reverse_dict 
 276. self._populate（） 
文件/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py在_populate 
 242.对于反向（self.url_patterns）中的模式：
文件/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py在url_patterns 
 332. raise不正确的配置（包含的urlconf％s没有任何其中的模式％self.urlconf_name
 
异常类型：/ works / add 
异常配置异常值：包含的urlconf url中没有任何模式
  

解决方案

问题可能是表单在加载网址之前定义。

Django 1.4将有一个 reverse_lazy 功能可以解决这个问题。您可以自己在项目中实施（请参见更改集16121 ）。

或者，您可以在窗体 __ init __ 方法中设置窗口小部件。然后在url加载后，创建表单时，反向调用。

  class WorkForm（forms.Form）：
＃... 
 subcategory = forms.ChoiceField（
 required = True，
 label = _（'SubCategory'），
 help_text = _（'哪个子类适合你的工作最好'）
）
 def __init __（self，* args，** kwargs）：
 super（WorkForm，self）.__ init __（* args，** kwargs）
 self.fields ['subcategory']。widget = DependantChoiceWidget（
 default_value = _（'Select category first'），
 data_source_url = reverse（'works-json-categories'），
 depends_on ='category_id'
），
  

I'm trying to use django's reverse() function in definition of django form for my custom widget, but am getting an error:

ImproperlyConfigured
The included urlconf urls doesn't have any patterns in it

Here is the code:

class WorkForm(forms.Form):
    # ...
    category = forms.ChoiceField(
        required=True,
        label=_('Category'),
        help_text=_('Select most appropriate category for your work.')
    )
    subcategory = forms.ChoiceField(
        widget=DependantChoiceWidget(
            default_value=_('Select category first'),
            data_source_url=reverse('works-json-categories'),
            # data_source_url='', -- it works this way
            depends_on='category_id'
        ),
        required=True,
        label=_('SubCategory'),
        help_text=_('Which subcategory suits your work best.')
    )

I am pretty sure, that my 'works.urls' is configured properly, since all other pages work as expected.

Is there a reason, why I cannot use reverse() in form definition? Does it have something to do with when this code runs? Is there a way to fix this, or the only choice here is to hardcode the URL?

Here is full error dump:

Environment:

Request Method: GET
Request URL: http://127.0.0.1:8000/works/add?category=1&subcategory=1

Django Version: 1.4 pre-alpha
Python Version: 2.7.1
Installed Applications:
['django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.sites',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.admin',
 'django.contrib.admindocs',
 'social_auth',
 'sorl.thumbnail',
 'helpers',
 'users',
 'works',
 'debug_toolbar']
Installed Middleware:
('django.middleware.common.CommonMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.transaction.TransactionMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'debug_toolbar.middleware.DebugToolbarMiddleware')


Traceback:
File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py" in get_response
  89.                     response = middleware_method(request)
File "/usr/local/lib/python2.7/dist-packages/django/middleware/common.py" in process_request
  67.             if (not _is_valid_path(request.path_info, urlconf) and
File "/usr/local/lib/python2.7/dist-packages/django/middleware/common.py" in _is_valid_path
  164.         urlresolvers.resolve(path, urlconf)
File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py" in resolve
  416.     return get_resolver(urlconf).resolve(path)
File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py" in resolve
  298.             for pattern in self.url_patterns:
File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py" in url_patterns
  328.         patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py" in urlconf_module
  323.             self._urlconf_module = import_module(self.urlconf_name)
File "/usr/local/lib/python2.7/dist-packages/django/utils/importlib.py" in import_module
  35.     __import__(name)
File "/var/www/megenius/trunk/urls.py" in <module>
  27.     url(r'^works/', include('works.urls')),
File "/usr/local/lib/python2.7/dist-packages/django/conf/urls/__init__.py" in include
  24.         urlconf_module = import_module(urlconf_module)
File "/usr/local/lib/python2.7/dist-packages/django/utils/importlib.py" in import_module
  35.     __import__(name)
File "/var/www/megenius/trunk/works/urls.py" in <module>
  2. from works.views import *
File "/var/www/megenius/trunk/works/views.py" in <module>
  9. from works.forms import WorkForm
File "/var/www/megenius/trunk/works/forms.py" in <module>
  10. class WorkForm(forms.Form):
File "/var/www/megenius/trunk/works/forms.py" in WorkForm
  31.             data_source_url=reverse('works-json-categories'),
File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py" in reverse
  473.                       (prefix, resolver.reverse(view, *args, **kwargs)))
File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py" in reverse
  360.         possibilities = self.reverse_dict.getlist(lookup_view)
File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py" in reverse_dict
  276.             self._populate()
File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py" in _populate
  242.         for pattern in reversed(self.url_patterns):
File "/usr/local/lib/python2.7/dist-packages/django/core/urlresolvers.py" in url_patterns
  332.             raise ImproperlyConfigured("The included urlconf %s doesn't have any patterns in it" % self.urlconf_name)

Exception Type: ImproperlyConfigured at /works/add
Exception Value: The included urlconf urls doesn't have any patterns in it

解决方案

The problem might be that the form is defined before the urls have been loaded.

Django 1.4 will have a reverse_lazy feature that would solve this problem. You could implement it in your project yourself (see changeset 16121).

Alternatively, you could set the widget in your forms __init__ method instead. Then the reverse call happens when the form is created, after the urls have loaded.

class WorkForm(forms.Form):
    # ...
    subcategory = forms.ChoiceField(
        required=True,
        label=_('SubCategory'),
        help_text=_('Which subcategory suits your work best.')
    )
    def __init__(self, *args, **kwargs):
        super(WorkForm, self).__init__(*args, **kwargs)
        self.fields['subcategory'].widget=DependantChoiceWidget(
            default_value=_('Select category first'),
            data_source_url=reverse('works-json-categories'),
            depends_on='category_id'
        ),

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