Utilizzando reverse() in Django forma

Question

Sto cercando di utilizzare la funzione di Django reverse() nella definizione della forma di Django per il mio widget personalizzato, ma sto ottenendo un errore:

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

Ecco il codice:

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.') 
    ) 

Sono sicuro che il mio "works.urls" è configurato correttamente, poiché tutte le altre pagine funzionano come previsto.

C'è una ragione, perché non riesco a utilizzare reverse() nella definizione del modulo? Ha qualcosa a che fare con questo codice? C'è un modo per risolvere questo problema, o l'unica scelta qui è quella di hardcode l'URL?

Qui è pieno di dettagli di errore:

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 

Answer 1

Il problema potrebbe essere che la forma è definita prima che gli URL sono stati caricati.

Django 1.4 avrà una funzione reverse_lazy che risolverebbe questo problema. Potresti implementarlo tu stesso nel tuo progetto (vedi changeset 16121).

In alternativa, è possibile impostare il widget nel metodo __init__ dei moduli. Quindi la chiamata inversa avviene quando viene creato il modulo, dopo che gli URL sono stati caricati.

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' 
     ),