Reverse for 'display_data' not found. 'display_data' is not a valid view function or pattern name

[ratnadeep ray]

Hi all, 

I am getting the below error when I am trying to load the home page:

Reverse for 'display_data' not found. 'display_data' is not a valid view function or pattern name

My views.py file is as follows: 

 

def home(request):
    #query_results = QRC_DB.objects.all()
return render(request, 'display_data.html')

def display_data(request,component):
    #query_results = QRC_DB.objects.all()
return HttpResponse("You're looking at the component %s." % component)

My urls.py file under the app is as follows: 

from django.urls import path

from fusioncharts import views

urlpatterns = [
        path('home/', views.home, name=''),
]

The urls.py file under the project is as follows: 

from django.contrib import admin
from django.urls import path,include
urlpatterns = [
    path('admin/', admin.site.urls),
    path('', include('fusioncharts.urls'))
]

And my html file (display_data) code is as follows : 

{% block content %}
  <h3>Display the test results</h3>
  <div id="container" style="width: 75%;">
    <canvas id="display-data"></canvas>
<li><a href="{% url 'display_data' 'SQL' %}">SQL</a></li>
  </div>
{% endblock %}

Can anyone please help me to find out the mistake ? 

Thanks. 

 

 

[Jorge Gimeno]

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NoReverseFound is one of those exceptions that I need a mental mapping for.  It's not necessarily easy to intuit the meaning from the name itself.  What works for me is that Django is saying "You've given me a named URL, and I can't find it."

In your template, there's a url tag. The first argument of a url tag is the named url it should insert there.  You give the tag 'display_data', but there is no urlpattern in either of your urls with the name set to 'display_data'.

In your fusioncharts/urls.py, I would add this (completely untested):

from django.urls import path

from fusioncharts import views

urlpatterns = [
        path('home/', views.home, name=''),

           path('display_data/<str:component>/', views.display_data, name='display_data'), # <- Added here!

]

Now we have a path with the same name that your template is looking for, you have a view it sends the data to, and you capture the variable that will be sent to the view.

Hope this helps!

-Jorge