Book Image

Drupal 8 Module Development

By : Daniel Sipos
Book Image

Drupal 8 Module Development

By: Daniel Sipos

Overview of this book

Drupal is an open source web-based content management system (CMS) that can be used for building anything from simple websites to complex applications. It enables individuals and organizations to build platforms that engage users and deliver the right content at the right time. Drupal 8 is an exciting new development in the Drupal community. However, the differences from the previous version are substantial and this can put quite some pressure on Drupal 7 developers that need to catch up. This book aims to help such developers in getting up to speed with Drupal 8 module development. The book first introduces you to the Drupal 8 architecture and its subsystems before diving into creating your first module with basic functionality. Building upon that, you will cover many core APIs and functionalities available to module developers. You will work with the Drupal logging and mailing systems, learn how to output data using the theme layer and work with menus and links programmatically. Then, you will learn how to work with different kinds of data storages, create custom entities, field types and leverage the Database API for lower level database queries. Moreover, you will learn about the Drupal 8 access system and caching layer as well as the APIs used for data processing (queues and batches). You will further see how to introduce javascript into your module, work with the various file systems and ensure the code you write works on multilingual sites. Finally, you will learn how to programmatically work with Views, write automated tests for your functionality and also write secure code in general. By the end of the book, you will have learned how to develop your own custom module from scratch that can help solve a small problem or even provide complex functionality. And who knows, maybe you’ll even contribute it back to the Drupal community.
Table of Contents (19 chapters)

Theming our Hello World module

The HelloWorldController we built in Chapter 2, Creating Your First Module, currently uses a service to retrieve the string to be used as the salutation and then returns a simple markup render array with it. Let's imagine now that we want to output this message, but wrap it in our own specific markup. To make an easy thing complicated, we want to break up the salutation string into parts so that they can be styled slightly differently. Additionally, we want to allow others to override our theme using suggestions that can depend on whether or not the salutation has been overridden via the configuration form. So, let's see how we can do these things.

To get things started, this is the markup we are after:

<div class="salutation">
Good morning <span class="salutation--target">world</span>
</div&gt...