Book Image

Web Development with Django

By : Ben Shaw, Saurabh Badhwar, Andrew Bird, Bharath Chandra K S, Chris Guest
Book Image

Web Development with Django

By: Ben Shaw, Saurabh Badhwar, Andrew Bird, Bharath Chandra K S, Chris Guest

Overview of this book

Do you want to develop reliable and secure applications which stand out from the crowd, rather than spending hours on boilerplate code? Then the Django framework is where you should begin. Often referred to as a 'batteries included' web development framework, Django comes with all the core features needed to build a standalone application. Web Development with Django takes this philosophy and equips you with the knowledge and confidence to build real-world applications using Python. Starting with the essential concepts of Django, you'll cover its major features by building a website called Bookr – a repository for book reviews. This end-to-end case study is split into a series of bitesize projects that are presented as exercises and activities, allowing you to challenge yourself in an enjoyable and attainable way. As you progress, you'll learn various practical skills, including how to serve static files to add CSS, JavaScript, and images to your application, how to implement forms to accept user input, and how to manage sessions to ensure a reliable user experience. Throughout this book, you'll cover key daily tasks that are part of the development cycle of a real-world web application. By the end of this book, you'll have the skills and confidence to creatively tackle your own ambitious projects with Django.
Table of Contents (17 chapters)
Preface

Validating Forms and Retrieving Python Values

So far, we have seen how Django Forms makes it much simpler to define a form using Python code and have it automatically rendered. We will now look at the other part of what makes Django forms useful: their ability to automatically validate the form and then retrieve native Python objects and values from them.

In Django, a form can either be unbound or bound. These terms describe whether or not the form has had the submitted POST data sent to it for validation. So far, we have only seen unbound forms – they are instantiated without arguments, like this:

form = ExampleForm()

A form is bound if it is called with some data to be used for validation, such as the POST data. A bound form can be created like this:

form = ExampleForm(request.POST)

A bound form allows us to start using built-in validation-related tools: first, the is_valid method to check the form's validity, then the cleaned_data attribute on the...