I'm hitting the following error when going through the Django tutorial:
Reverse for 'detail' with arguments '('',)' not found. 1 pattern(s) tried: ['polls\\/(?P<question_id>[0-9]+)\\/$']
From this answer it seems like the problem is that the argument is not being passed through on line 9 of results.html.
This answer suggests that it should be question.id but that's what I have. So I'm not sure where to go next on this. part following error. When I remove line 9 (which includes this link) from the template. Help appreciated. Apologies if this has already been asked before - I feel like I've looked everywhere.
Hopefully this is all the relevant code. (After this went wrong a couple of times I copied and pasted everything from the tutorial to guard against typos.)
Traceback
Environment:
Request Method: GET
Request URL: http://127.0.0.1:8000/polls/1/results/
Django Version: 2.0.3
Python Version: 3.6.4
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'polls.apps.PollsConfig']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware']
Template error:
In template C:\Users\User\Dropbox\Personal\Projects\Python\Django\django-tut\mysite\polls\templates\polls\results.html, error at line 8
Reverse for 'detail' with arguments '('',)' not found. 1 pattern(s) tried: ['polls\\/(?P<question_id>[0-9]+)\\/$']
1 : <h1>{{ question.question_text }}</h1>
2 :
3 : <ul>
4 : {% for choice in question.choice_set.all %}
5 : <li>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}</li>
6 : {% endfor %}
7 : </ul>
8 : <a href=" {% url 'polls:detail' question.id %} ">Vote again?</a>
9 :
Traceback:
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\core\handlers\exception.py" in inner
35. response = get_response(request)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\core\handlers\base.py" in _get_response
128. response = self.process_exception_by_middleware(e, request)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\core\handlers\base.py" in _get_response
126. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\User\Dropbox\Personal\Projects\Python\Django\django-tut\mysite\polls\views.py" in results
19. return render(request, 'polls/results.html', {question:question})
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\shortcuts.py" in render
36. content = loader.render_to_string(template_name, context, request, using=using)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\template\loader.py" in render_to_string
62. return template.render(context, request)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\template\backends\django.py" in render
61. return self.template.render(context)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\template\base.py" in render
175. return self._render(context)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\template\base.py" in _render
167. return self.nodelist.render(context)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\template\base.py" in render
943. bit = node.render_annotated(context)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\template\base.py" in render_annotated
910. return self.render(context)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\template\defaulttags.py" in render
447. url = reverse(view_name, args=args, kwargs=kwargs, current_app=current_app)
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\urls\base.py" in reverse
88. return iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs))
File "C:\Users\User\AppData\Local\Programs\Python\Python36-32\Lib\site-packages\django\urls\resolvers.py" in _reverse_with_prefix
632. raise NoReverseMatch(msg)
Exception Type: NoReverseMatch at /polls/1/results/
Exception Value: Reverse for 'detail' with arguments '('',)' not found. 1 pattern(s) tried: ['polls\\/(?P<question_id>[0-9]+)\\/$']
polls/urls.py
from django.urls import path
from . import views
app_name = 'polls'
urlpatterns = [
path('', views.index, name='index'),
path('<int:question_id>/', views.detail, name='detail'),
path('<int:question_id>/results/', views.results, name='results'),
path('<int:question_id>/vote/', views.vote, name='vote'),
]
mysite/urls.py
from django.urls import include, path
from django.contrib import admin
urlpatterns = [
path('polls/', include('polls.urls')),
path('admin/', admin.site.urls),
#path('<int:question_id>/', views.detail, name='detail'),
]
polls/results
<h1>{{ question.question_text }}</h1>
<ul>
{% for choice in question.choice_set.all %}
<li>{{ choice.choice_text }} -- {{ choice.votes }} vote{{ choice.votes|pluralize }}</li>
{% endfor %}
</ul>
<a href="{% url 'polls:detail' question.id %}">Vote again?</a>
polls/views.py
from django.shortcuts import get_object_or_404, render
from django.http import HttpResponseRedirect, HttpResponse
from django.urls import reverse
from .models import Choice, Question
def index(request):
latest_question_list = Question.objects.order_by('-pub_date')[:5]
context = {'latest_question_list': latest_question_list}
return render(request, 'polls/index.html', context)
def detail(request, question_id):
question = get_object_or_404(Question, pk=question_id)
return render(request, 'polls/detail.html', {'question':question})
def results(request, question_id):
question = get_object_or_404(Question, pk=question_id)
return render(request, 'polls/results.html', {question:question})
def vote(request, question_id):
question = get_object_or_404(Question, pk=question_id)
try:
selected_choice = question.choice_set.get(pk=request.POST['choice'])
except (KeyError, Choice.DoesNotExist):
# Redisplay the question voting form.
return render(request, 'polls/detail.html', {
'question': question,
'error_message': "You didn't select a choice.",
})
else:
selected_choice.votes += 1
selected_choice.save()
# Always return an HttpResponseRedirect after successfully dealing
# with POST data. This prevents data from being posted twice if a
# user hits the Back button.
return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))
