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.

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Table of Contents (19 chapters)
Preface
Preface
What this book covers
What you need for this book
Who this book is for
Conventions
Reader feedback
Customer support
Free Chapter
1
Developing for Drupal 8
Developing for Drupal 8
Introducing Drupal (for developers)
Developing for Drupal 8
Summary
2
Creating Your First Module
Creating Your First Module
Creating a module
Using services in Drupal 8
Blocks
Working with links
Event Dispatcher and redirects
Summary
3
Logging and Mailing
Logging and Mailing
Logging
Mail API
Tokens
Summary
4
Theming
Theming
Business logic versus presentation logic
Twig
Theme hooks
Theme hook suggestions
Render arrays
Assets and libraries
Common theme hooks
Attributes
Theming our Hello World module
Summary
5
Menus and Menu Links
Menus and Menu Links
The menu system
Rendering menus
Working with menu links
Defining local tasks
Defining local actions
Defining contextual links
Summary
6
Data Modeling and Storage
Data Modeling and Storage
Different types of data storage
State API
Tempstore
UserData
Configuration
Entities
TypedData
Interacting with the Entity API
Summary
7
Your Own Custom Entity and Plugin Types
Your Own Custom Entity and Plugin Types
Custom content entity type
Drush command
Summary
8
The Database API
The Database API
The Schema API
Running queries
Summary
9
Custom Fields
Custom Fields
Field type
Field widget
Field formatter
Field settings
Using as a base field
Summary
10
Access Control
Access Control
Introduction to the Drupal access system
Defining permissions
Checking the user credentials
Route access
Entity access
Block access
Summary
11
Caching
Caching
Introduction
Cacheability metadata
Placeholders and lazy building
Using the Cache API
Summary
12
JavaScript and the Ajax API
JavaScript and the Ajax API
JavaScript in Drupal
Ajax API
Summary
13
Internationalization and Languages
Internationalization and Languages
Introduction
Internationalization
Content entities and the Translation API
Summary
14
Batches, Queues, and Cron
Batches, Queues, and Cron
Batch powered update hooks
Batch operations
Cron
Queues
Summary
15
Views
Views
Entities in Views
Exposing custom data to Views
Custom Views field
Custom Views filter
Custom Views argument
Views theming
Views hooks
Summary
16
Working with Files and Images
Working with Files and Images
The filesystem
Stream wrappers
Managed versus unmanaged files
Using the File and Image fields
Working with managed files
Our own stream wrapper
Working with unmanaged files
Private file system
Images
Summary
17
Automated Testing
Automated Testing
Testing methodologies in Drupal 8
PHPUnit
Registering tests
Unit tests
Kernel tests
Functional tests
Functional JavaScript tests
Summary
18
Drupal 8 Security
Drupal 8 Security
Cross-Site Scripting (XSS)
SQL Injection
Cross-Site Request Forgery (CSRF)
Summary

Using the File and Image fields

In order to demonstrate how to work with managed files, we will go back to our Product entity importer and bring in some images for each product. However, in order to store them, we need to create a field on the Product entity. This will be an image field.

Instead of creating this field through the UI and attaching it to a bundle, let's do it the programmatic way and make it a base field (available on all bundles). We won't need to do anything complex, for now we are only interested in a basic field that we can use to store the images we bring in from the remote API. It can look something like this:

$fields['image'] = BaseFieldDefinition::create('image')
  ->setLabel(t('Image'))
  ->setDescription(t('The product image.'))
  ->setDisplayOptions('form', array(
    'type&apos...
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