The request/response cycle

Let’s review the request/response cycle of Django with the application we built. The following schema shows a simplified example of how Django processes HTTP requests and generates HTTP responses:

Figure 1.19: The Django request/response cycle

Let’s review the Django request/response process:

A web browser requests a page by its URL, for example, https://domain.com/blog/33/. The web server receives the HTTP request and passes it over to Django.

Django runs through each URL pattern defined in the URL patterns configuration. The framework checks each pattern against the given URL path, in order of appearance, and stops at the first one that matches the requested URL. In this case, the pattern /blog/<id>/ matches the path /blog/33/.

Django imports the view of the matching URL pattern and executes it, passing an instance of the HttpRequest class and the keyword or positional arguments. The view uses the models to retrieve information from the database. Using the Django ORM, QuerySets are translated into SQL and executed in the database.

The view uses the render() function to render an HTML template passing the Post object as a context variable.

The rendered content is returned as a HttpResponse object by the view with the text/html content type by default.

You can always use this schema as the basic reference for how Django processes requests. This schema doesn’t include Django middleware, for the sake of simplicity. You will use middleware in different examples of this book, and you will learn how to create custom middleware in Chapter 17, Going Live.