I'm getting a NoReverseMatch error when I go into the DetailView

Question

Every time I create a post in my website I always get a NoReverseMatch error when it redirects to the detail view of the app. I can't find the answer in the internet.

Views.py:

from django.shortcuts import render
from django.views import generic
from django.contrib.auth.mixins import LoginRequiredMixin
from django.urls import reverse_lazy 
from . import forms
from . import models
# Create your views here.

class AnnouncementListView(generic.ListView,LoginRequiredMixin):
    model = models.Announcement

class AnnouncementDetailView(generic.DetailView, LoginRequiredMixin):
    model = models.Announcement

class AnnouncementUpdateView(generic.UpdateView, LoginRequiredMixin):
    model = models.Announcement
    form_class = forms.AnnouncementForm

class AnnouncementCreateView(generic.CreateView, LoginRequiredMixin):
    model = models.Announcement
    form_class = forms.AnnouncementForm

class AnnouncementDeleteView(generic.DeleteView, LoginRequiredMixin):
    model = models.Announcement
    success_url = reverse_lazy('announcement:single')

    def get_queryset(self):
        queryset = super().get_queryset()
        return queryset.filter(user_id=self.request.user.id)

    def delete(self, *args, **kwargs):
        messages.success(self.request, "Post Deleted")
        return super().delete(*args, **kwargs)

Urls.py:

from django.urls import path
from . import views

app_name = 'announcement'

urlpatterns = [
    path('create/', views.AnnouncementCreateView.as_view(), name='create'),
    path('', views.AnnouncementListView.as_view(), name='list'),
    path('posts/<int:pk>/', views.AnnouncementDetailView.as_view(), name='single'),
    path('delete/<int:pk>/', views.AnnouncementDeleteView.as_view(), name='destroy'),
]

announcement_detail.html:

{% extends 'base.html' %}


{% block content %}
<div class="container">
  <h1>{{announcement.title}}</h1>
    <p>{{announcement.text}}</p>
    <span>{{announcement.date}}</span>

    <a href="{% url 'announcement:destroy' %} "><svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="currentColor" class="bi bi-eraser-fill" viewBox="0 0 16 16">
        <path d="M8.086 2.207a2 2 0 0 1 2.828 0l3.879 3.879a2 2 0 0 1 0 2.828l-5.5 5.5A2 2 0 0 1 7.879 15H5.12a2 2 0 0 1-1.414-.586l-2.5-2.5a2 2 0 0 1 0-2.828l6.879-6.879zm.66 11.34L3.453 8.254 1.914 9.793a1 1 0 0 0 0 1.414l2.5 2.5a1 1 0 0 0 .707.293H7.88a1 1 0 0 0 .707-.293l.16-.16z"/>
      </svg></a>
</div>
    
{% endblock  %}

Error:

Answer 1

You need to pass the primary key of the announcement to destroy:

{% url 'announcement:destroy' announcement.pk %}

But a delete view will not be triggered with a GET request, but with a POST request, this is because a GET request is not supposed to create/update/remove entities.

You thus need to make a mini-form:

<form method="post" action="{% url 'announcement:destroy' announcement.pk %}">
    {% csrf_token %}
    <button type="submit">delete</button>
</form>

Furthermore the mixins should be put before the view, since otherwise these end up at the end of the method resolution order (MRO):

class AnnouncementDeleteView(LoginRequiredMixin, generic.DeleteView):
    # …

As @NKSM says, the success_url of your AnnounceDeleteView has the same problem. You should redirect to the list, or you should override get_success_url, but here it makes no sense to redirect to the detail view of the removed item, since it is removed:

from django.urls import reverse_lazy

class AnnouncementDeleteView(LoginRequiredMixin, generic.DeleteView):
    model = models.Announcement
    success_url = reverse('announcement:list')
    # …