Django middleware is a light, low-level plug-in system that allows developers to hook into the Django’s request/response process at a global level. The concept originates from Django’s emphasis on reusability, it promotes the principle of DRY (Don’t Repeat Yourself), which can be translated into seamless user experiences.
Middleware in Django can be seen as a series of hooks into Django’s request/response processing. It’s a way to plug extentions to Django’s functionality, adding functionalities into the request/response path. Middleware classes process requests before they reach the view and responses before they leave the view (Django Documentation, n.d.).
As per Django’s documentation, when a request is made to a Django application, it passes through a series of middleware before reaching the view, and vice versa for the response. Middleware can be used to process requests, view responses, or create new requests/responses in a variety of ways. They can perform various tasks such as session management, user authentication, cross-site request forgery protection, content Gzipping, and more.
Some examples of Django middleware include:
1. `AuthenticationMiddleware`: According to Django’s documentation, this middleware associates users with requests using sessions.
1. `SessionMiddleware`: This middleware manages sessions across requests.
1. `CommonMiddleware`: This middleware provides several convenience services such as appending trailing slashes, prepending ‘www.’ to URLs, and providing flat page fallback for 404 errors.
1. `CsrfViewMiddleware`: This middleware provides protection against Cross Site Request Forgeries by adding hidden form fields and checking requests for the correct value.
1. `CacheMiddleware`: As per Django’s documentation, this middleware provides site-wide caching.
To use a middleware, you must add it to the `MIDDLEWARE` setting in your Django settings file. The order of middleware classes matters because a few middleware might depend on others and middleware are applied in the order of top-down and bottom-up for requests and response respectively.
For example, if you wanted to add the AuthenticationMiddleware, in your settings file you would add:
```
MIDDLEWARE = [
‘django.contrib.sessions.middleware.SessionMiddleware’,
‘django.middleware.common.CommonMiddleware’,
‘django.middleware.csrf.CsrfViewMiddleware’,
‘django.contrib.auth.middleware.AuthenticationMiddleware’,
]
```
Each middleware class in Django has defined methods (process_request(), process_view(), process_template_response(), process_response() and process_exception()) that Django calls during the processing of the request and response.
In summary, Django middleware offers a convenient mechanism for coupling loosely related functionality into reusable components.
Source(s):
1. Django Documentation. (n.d.). Middleware | Django documentation | Django. https://docs.djangoproject.com/en/4.0/topics/http/middleware/
2. Real Python. (2021, August 13). Django Middleware: A Guide. https://realpython.com/django-middleware/
DISCLAIMER: The URLs might need to be updated as Django progresses and updates its versions.
