Are you ready to learn how to extend and customize Drupal sites in code? The Drupal Module Developer Guide will introduce you to extending Drupal with modules. You will learn foundational concepts and get hands-on practice with a variety of APIs used in Drupal coding and development. We'll be extending the site we built in the Drupal User Guide. If you're new to Drupal site building, we recommend that you walk through the Drupal User Guide first.
Drupal offers module developers several methods for creating different types of links, all defined by module configuration. This tutorial explores these types of links, how they relate to each other, and when to use them.
In this tutorial, we'll learn:
- The nature of menu items, action links, and local task links.
- Examples of each link type in Drupal's UI and their application in our scenario.
- Criteria for selecting the appropriate link type for adding the weather page to site navigation.
By the end of this tutorial, you'll understand the different types of links in Drupal and how they apply to adding navigational elements for custom module pages.
Permissions in Drupal control access to features and functions. Modules define permissions, which allow site administrators to grant or restrict access based on user roles. As a module developer, you'll create new permissions to restrict access to your module's custom features, independent of existing permissions defined by other modules.
In this tutorial, we'll:
- Explore how and where permissions are defined within a module.
- Discuss the concept of static and dynamic permissions in Drupal.
By the end of this tutorial, you'll have a clear understanding of how permissions function in Drupal and their implementation in modules.
Modules can define custom permissions to restrict access to specific routes or page sections. This control allows module developers to provide granular access while enabling site administrators to manage user privileges. We'll add a view weekly weather
permission via the anytown module to limit access to the weather page.
In this tutorial, we'll:
- Create an MODULE_NAME.permissions.yml file.
- Define a new permission.
- Use the new permission to restrict access to a route.
By the end of this tutorial, you should be able to define a new permission in a module and use it to control access to a route.
Custom services in Drupal modules encapsulate specific business logic or functionality. In our example, we'll demonstrate moving code required to access a weather forecast API from a controller into a service. This will help make our controller thin and our module code more reusable, testable, and maintainable.
In this tutorial, we'll:
- Explore the advantages of custom services for managing business logic.
- Define the components of a custom service.
By the end of this tutorial, you'll understand why creating custom services is a beneficial practice in Drupal module development.
To access services in Drupal through the service container, you'll need to know the unique machine name of the service. We'll use the example of making HTTP requests to a weather forecast API in the anytown module to demonstrate several methods you can use to identify an existing service's ID.
In this tutorial, we'll:
- Discover existing services and their machine names.
- Take a look at an example service definition.
By the end of this tutorial, you should be able to locate and use existing services in your Drupal module.
Concept: Testing
FreeTesting ensures that code remains reliable and functional. This tutorial introduces the primary types of tests in Drupal: Unit, Kernel, Functional, and FunctionalJavascript -- all executed via PHPUnit. We'll clarify the differences between each type of test and appropriate use cases. As module developers, understanding what to test and how to write tests is vital for robust and maintainable code.
In this tutorial, we'll:
- Identify the primary test types in Drupal and their use cases.
- Emphasize the importance of functional tests in custom module development.
- Introduce the basics of authoring tests in a custom module.
By the end of this tutorial, you should recognize the different types of tests Drupal uses and when and how to use each kind.
Before you can run tests, you'll need to configure your local environment. This setup involves Drupal-specific configuration for PHPUnit and ensuring your environment supports Functional JavaScript tests with a WebDriver client and a compatible browser. The setup process varies based on the development environment. In this tutorial, we're using DDEV as the local environment.
In this tutorial, we'll:
- Install all required dependencies.
- Configure PHPUnit specific to our environment.
- Validate the setup by running a Drupal core test.
By the end of this tutorial, you'll be equipped to run Drupal's PHPUnit tests locally using DDEV.
Functional tests simulate user interactions with Drupal applications, which enables us to test user interfaces and complex workflows. This tutorial guides you through writing functional tests for the anytown module, focusing on custom user registration workflow enhancements.
In this tutorial, we'll:
- Examine functional test structure.
- Test
anytown_form_user_register_form_alter()
customizations. - Discuss the functional test execution environment.
By the end of this tutorial, you'll know how to write functional tests that emulate browser interactions with your Drupal application.
Kernel tests in Drupal enable module integration testing with Drupal core systems in a bootstrapped environment. Kernel tests bridge the gap between unit and functional tests. This tutorial focuses on writing kernel tests for the anytown module, specifically to test the ForecastClient
service's caching logic and custom username validation.
In this tutorial, we'll:
- Explore the parts of a kernel test.
- Write kernel tests for anytown module features.
- Use mocks and the Drupal container in kernel tests.
By the end of this tutorial, you should be able to get started writing kernel tests to verify your module's integration with Drupal core.
Unit tests are the simplest among Drupal's test types, ideal for verifying code that performs computations. This tutorial guides through writing unit tests for the anytown module, focusing on the ForecastClient
service, and illustrates how to use mocks for dependencies.
In this tutorial, we'll:
- List potential unit tests for the anytown module.
- Write tests for
ForecastClient
service logic. - Demonstrate how to mock services in unit tests.
By the end of this tutorial you should be able to write PHPUnit Unit tests for logic in the anytown module.
How to configure content items to make them translatable.
How to translate field labels in a view, and other configuration.
How to enable maintenance mode to set up a "Site under maintenance" message, and how to disable it.
How to download and install a module from Drupal.org.
How to download and install a theme from Drupal.org.