I want to solve Django NoReverseMatch

Question

There is a problem here. I don't know how to solve this. Please help me. error

source Code

results.html

<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>

views.py-polls

from django.shortcuts import get_object_or_404, render
from django.http import HttpResponseRedirect, HttpResponse
from django.urls import reverse
from polls.models import Question, Choice

# Create your views here.
def index(request):
    latest_question_list = Question.objects.all().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 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):
        return render(request, 'polls/detail.html',{
            'question': question,
            'error_message': "You didn't select a choice.",
        })
    else:
        selected_choice.votes += 1
        selected_choice.save()
        return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))

def results(request, question_id):
    question = get_object_or_404(Question, pk=question_id)
    return render(request, 'polls/results.html', {'question': question})

Somehow there seems to be an error here. I don't think the reverse is the polls:results. Of course this is conjecture.

urls.py-fistsite

from django.contrib import admin
from django.urls import path, include
from polls import views

urlpatterns = [
    path('polls/', include('polls.urls')),
    path('admin/', admin.site.urls), 
    path('', views.index, name='index'),
]

urls.py-polls

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')
]

Answer 1

You have not passed variable question_id into template context.

In your template you can use question object instead

<a href="{% url 'polls:detail' question.id %}">Vote again?</a>