Book Image

Drupal 9 Module Development - Third Edition

By : Daniel Sipos
Book Image

Drupal 9 Module Development - Third Edition

By: Daniel Sipos

Overview of this book

With its latest release, Drupal 9, the popular open source CMS platform has been updated with new functionalities for building complex Drupal apps with ease. This third edition of the Drupal Module Development guide covers these new Drupal features, helping you to stay on top of code deprecations and the changing architecture with every release. The book starts by introducing you to the Drupal 9 architecture and its subsystems before showing you how to create your first module with basic functionality. You’ll explore the Drupal logging and mailing systems, learn how to output data using the theme layer, and work with menus and links programmatically. Once you’ve understood the different kinds of data storage, this Drupal guide will demonstrate how to create custom entities and field types and leverage the Database API for lower-level database queries. You’ll also learn how to introduce JavaScript into your module, work with various file systems, and ensure that your code works on multilingual sites. Finally, you’ll work with Views, create automated tests for your functionality, and write secure code. By the end of the book, you’ll have learned how to develop custom modules that can provide solutions to complex business problems, and who knows, maybe you’ll even contribute to the Drupal community!
Table of Contents (20 chapters)
3
Chapter 3: Logging and Mailing

Introduction to caching

The first thing I would like to mention before getting into the meat of the Cache API is that this subsystem is one of the best documented ones (at the time of writing). You can check out the main entry page (https://www.drupal.org/docs/8/api/cache-api/cache-api) and I recommend keeping it close by when developing. At the time of writing, this was still under the Drupal 8 API section, but as you know, Drupal 9 is Drupal 8.

The cache system in Drupal provides the API needed to handle the creation, storage, and invalidation of cached data. From a storage perspective, it is extensible, allowing us to write our own custom cache backends (CacheBackendInterface). By default, however, cache data gets stored in the database and hence the default backend is DatabaseBackend. Going forward, we will focus only on this implementation since it is the most commonly used one, especially when starting a new project. Quite often though, once the site becomes more complex,...