1. Introduction to Django

Overview

This chapter introduces you to Django and its role in web development. You will begin by learning how the Model View Template (MVT) paradigm works and how Django processes HTTP requests and responses. Equipped with the basic concepts, you'll create your first Django project, called Bookr, an application for adding, viewing, and managing book reviews. It's an application you'll keep enhancing and adding features to throughout this book. You will then learn about the manage.py command (used to orchestrate Django actions). You will use this command to start the Django development server and test whether the code you've written works as expected. You will also learn how to work with PyCharm, a popular Python IDE that you'll be using throughout this book. You will use it to write code that returns a response to your web browser. Finally, you'll learn how to use PyCharm's debugger to troubleshoot problems with...

Introduction

"The web framework for perfectionists with deadlines." It's a tagline that aptly describes Django, a framework that has been around for over 10 years now. It is battle-tested and widely used, with more and more people using it every day. All this might make you think that Django is old and no longer relevant. On the contrary, its longevity has proved that its Application Programming Interface (API) is reliable and consistent, and even those who learned Django v1.0 in 2007 can mostly write the same code for Django 3 today. Django is still in active development, with bugfixes and security patches being released monthly.

Like Python, the language in which it is written, Django is easy to learn, yet powerful and flexible enough to grow with your needs. It is a "batteries-included" framework, which is to say that you do not have to find and install many other libraries or components to get your application up and running. Other frameworks, such as...

Scaffolding a Django Project and App

Before diving deep into the theory behind Django paradigms and HTTP requests, we'll show you how easy it is to get a Django project up and running. After this first section and exercise, you will have created a Django project, made a request to it with your browser, and seen the response.

A Django project is a directory that contains all the data for your project: code, settings, templates, and assets. It is created and scaffolded by running the django-admin.py command on the command line with the startproject argument and providing the project name. For example, to create a Django project with the name myproject, the command that is run is this:

django-admin.py startproject myproject

This will create the myproject directory, which Django populates with the necessary files to run the project. Inside the myproject directory are two files (shown in Figure 1.1):

Figure 1.1: Project directory for myproject

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Model View Template

A common design pattern in application design is Model View Controller (MVC), where the model of the application (its data) is displayed in one or more views and a controller marshals interaction between the model and view. Django follows a somewhat similar paradigm called Model View Template (MVT).

Like MVC, MVT also uses models for storing data. However, with MVT, a view will query a model and then render it with a template. Usually, with MVC languages, all three components need to be developed with the same language. With MVT, the template can be in a different language. In the case of Django, the models and views are written in Python and the Template in HTML. This means that a Python developer could work on the models and views, while a specialist HTML developer works on the HTML. We'll first explain models, views, and templates in more detail, and then look at some example scenarios where they are used.

Models

Django models define the data for...

Summary

This chapter was a quick introduction to Django. You first got up to speed on the HTTP protocol and the structure of HTTP requests and responses. We then saw how Django uses the MVT paradigm, and then how it parses a URL, generates an HTTP request, and sends it to a view to get an HTTP response. We scaffolded the Bookr project and then created the reviews app for it. We then built two example views to illustrate how to get data from a request and use it when rendering templates. You should have experimented to see how Django escapes output in HTML when rendering a template.

You did all this with the PyCharm IDE, and you learned how to set it up to debug your application. The debugger will help you find out why things aren't working as they should. In the next chapter, you will start to learn about Django's database integration and its model system, so you can start storing and retrieving real data for your application.