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Python Django Basics Final Details url Tag

Posted by willdenn
willdenn
1,552 Points

Error during template rendering "NoReverseMatch at /courses/"

I've been following along precisely with the videos and everything has worked so far but at 6:24 I enter the code as Kenneth did and get the error in the title. I can't figure out what went wrong. More specifically the error is: 

Error during template rendering

In template /home/treehouse/workspace/learning_site/courses/templates/courses/course_list.html, error at line 9
Reverse for 'detail' with arguments '()' and keyword arguments '{'pk': 1}' not found. 0 pattern(s) tried: []
1   {% extends "layout.html" %}
2   
3   {% block title %}Available Courses{% endblock %}
4   
5   {% block content %}
6   <div class="cards">
7           {% for course in courses %}
8           <div class="card">
9   
                  <header><a href="
      {% url 'detail' pk=course.pk %}
      ">{{ course.title }}</a></header>

10                  <div class="card-copy">
11                    {{ course.description }}
12                  </div>
13          </div>
14          {% endfor %}
15    </div>
16  
17  {% endblock %}

[MOD: wrapped codeblock in ```html+jinja formatting -cf]

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,454 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,454 Points

Look at the URL definition for 'detail'. The error message says your are calling this URL with the keyword argument "pk=1". Does your URL have a (?P<pk>) in it? The named group in the URL needs to match the keyword used in the template tag.

willdenn
willdenn
1,552 Points

Chris thanks for your attention. Yes the URL has (?P<pk>) (<.p.k.> keeps being formatted out of this for some reason) in it. It's the last url in urlpatterns in courses app's urls.py:

from django.conf.urls import url

from . import views

urlpatterns = [
    url(r'^$', views.course_list),

    url(r'(?P<course_pk>\d+)/(?P<step_pk>\d+)/', views.step_detail),
    url(r'(?P<pk>\d+)/', views.course_detail),
]

and here's the relevant view in views.py:

def course_detail(request, pk):
    course = get_object_or_404(Course, pk=pk)
    return render(request, 
                  'courses/course_detail.html', {'course': course})
Chris Freeman
Chris Freeman
Treehouse Moderator 68,454 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,454 Points

The error seems to be with the view course_list not course_detail.

What view calls course_list.html?

willdenn
willdenn
1,552 Points

Chris, this is the view for course_list.html:

def course_list(request):
    courses = Course.objects.all()
    return render(request, 'courses/course_list.html', {'courses': courses})

Also, I edited my comment a few times and you responded quickly (thanks!) but can you please confirm that you are responding to my comment in its final form?

Chris Freeman
Chris Freeman
Treehouse Moderator 68,454 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,454 Points

In order to do a reverse URL lookup from a template, the URL needs to have a name:

url(r'(?P<pk>\d+)/', views.course_detail, name='detail'),
willdenn
willdenn
1,552 Points

Perfect, that fixed it! Thanks Chris!