Django URL patterns | Python

In Django, views are Python functions which take a URL request as parameter and return an HTTP response or throw an exception like 404. Each view needs to be mapped to a corresponding URL pattern. This is done via a Python module called URLConf(URL configuration)

Let the project name be myProject. The Python module to be used as URLConf is the value of ROOT_URLCONF in myProject/settings.py. By default this is set to 'myProject.urls'. Every URLConf module must contain a variable urlpatterns which is a set of URL patterns to be matched against the requested URL. These patterns will be checked in sequence, until the first match is found. Then the view corresponding to the first match is invoked. If no URL pattern matches, Django invokes an appropriate error handling view.

Including other URLConf modules
It is a good practice to have a URLConf module for every app in Django. This module needs to be included in the root URLConf module as follows:

This tells Django to search for URL patterns in the file books/urls.py.

URL patterns

Here’s a sample code for books/urls.py:

For example,

• A URL request to /books/crime/ will match with the second URL pattern. As a result, Django will call the function views.books_by_genre(request, genre = "crime").
• Similarly a URL request /books/25/ will match the first URL pattern and Django will call the function views.book_detail(request, pk =25).

Here, int and str are path convertors and capture an integer and string value respectively.

Path convertors:
The following path convertor types are available in Django

• int – Matches zero or any positive integer.
• str – Matches any non-empty string, excluding the path separator(‘/’).
• slug – Matches any slug string, i.e. a string consisting of alphabets, digits, hyphen and under score.
• path – Matches any non-empty string including the path separator(‘/’)
• uuid – Matches a UUID(universal unique identifier).