June 11, 2020, 7:14 p.m.

Fixing NoReverseMatch error - What is NoReverseMatch exception in django

The NoReverseMatch error is an indication that Django is unable to find a matching URL pattern. Thus, the NoReverseMatch exception in Django is related to URL configuration.

If we are not passing arguments in URLs then it is super easy to handle the requests i.e routing the request from rendered template to view's function through URL.
But the problem arises when we have to pass arguments in URLs. If you are new in web development field (using Django framework) then I am sure you will definitely stick with NoReverseMatch error even for a single instance. This is so annoying and easy to solve as well if you understand the concept logically.

So today I am going to teach you how you can solve NoReverseMatch error in Django. Just follow this article and at the end of the day you will be able to understand the concept of NoReverseMatch exception and the solution as well.

url() vs Path()
To solve our problem lets understand the concept of url() and path() first. The older versions of Django (i.e before django1.1) uses url() but after django1.11 a new method called path() was introduced. If you don't know the difference between path and url then you should read this valuable article :
Path() vs url()
I am sure as hell that 98% of you can solve the NoReverseMatch error just by reading the difference between url() and path()

Anyway i am going to explain the concept by using an example.
Note : Always remember that the urls are case sensitive.

You are definitely getting any one or more issues from the following list, so To start debugging, you need to start by analyzing the error message given to you:
1) NoReverseMatch at /my_url/
This is the URL that is currently being rendered, this is the URL that your web app is currently trying to access but it (i.e the template) contains a URL that cannot be matched. So find this url (in template) and solve the problem associated with that particular url (check urls.py and views.py).
2) Reverse for 'my_url_name'
This is the name of the url that it cannot find. "name" is provided to the urls to avoid collision with other urls (may be with other app urls).
So it is better to use "myapp-comments" instead of "comments" (example).
3) with arguments '()' and
These are the non-keyword arguments its (i.e the template) providing to the URL
4) keyword arguments '{}' not found.
These are the keyword arguments its (i.e the template) providing to the url
5) N pattern(s) tried: [ ]
These are the patterns that the django was able to find in your urls.py files that it tried to match against.

To solve the issues here are some tips :
The first thing is , please stop using url() . It is super easy to handle urls using path()
The second thing is , please do not try to use regex or regular expression in path() because path does not support regular expressions.

How to write urls ? You can use the following ways if you want to pass argument/arguments in your url. I am also writing the method i.e the GET request method which is very helpful to pass argument or multiple arguments in urls.
#In template
<a href="{% url 'Post' id=7 %}">Post</a> #1
OR
<a href="{% url 'Post' id=Post_object.id %}">Post</a> #2
OR
<a href="{% url 'Post' %}?id=7">Post</a> #3
OR
<a href="{% url 'Post' %}?id=7&name={{Post_object.username}}">Post</a> #4

#In urls.py
path('Post/< int:id >/',views.ShowPost,name='Post') #for 1,2
OR
path('Post/',views.MyPost,name='Post') #for 3,4

#In views.py
def ShowPost(request,id):
   #do anything

def MyPost(request):
   id=int(request.GET.get('id'))
   user=request.GET.get('username')
   #do anything

Hence sometimes sending data through GET request is very efficient and easy as shown in this example. I also explained that how you can send multiple arguments in GET request and how you can access arguments or values in views.py sent with GET request method.






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