Hooks in Drupal are predefined points in the code where developers can insert custom functions to modify or extend core behavior without altering core files. Hooks are essential for implementing custom functionality while leaving core files untouched, keeping the site upgradeable.
This course covers what hooks are, how they enable modules to alter or extend Drupal's core functionality, and the process of implementing, discovering, and defining new hooks. By the end of the course, learners will be equipped with the knowledge to effectively use hooks to customize and enhance their Drupal projects, ensuring modular and maintainable code.
Key topics
- Overview of hooks, their purpose, and how they work
- Types of hooks
- How to implement any hook
- Methods to discover available hooks
- Invoking hooks so others can extend your code
- Best practices for organizing and documenting hooks
What Are Hooks?
FreeHooks allow modules to alter and extend the behavior of Drupal core, or another module. They are one of the various ways that code components in Drupal can communicate with one another. Using hooks a module developer can change how core or another module works -- without changing the existing code. As a Drupal developer, understanding how to implement and invoke hooks is essential.
In this tutorial we'll:
- Define what hooks are and the types of hooks that exist
- Understand the use case for hooks
Hooks allow module developers to execute custom code at key moments during Drupal's request processing life cycle. They can be used to react to actions or conditions, alter forms and existing configuration, and extend Drupal in various ways. Knowing how to implement a hook is an essential skill for any Drupal developer.
In this tutorial we'll walk through the process of locating the documentation for a specific hook, and then implementing it. All hooks are implemented in the same way, so once you know how to implement one, you'll be able to implement any.
How do you figure out what hooks are available to implement? How do you know which hook to implement to accomplish a task?
The list of hooks that are available to implement in your custom Drupal module varies depending on the modules enabled for a site. Each module can optionally invoke new hooks. There are also some hooks invoked by Drupal core subsystems like Form API that are always present. This can make it a little bit tricky sometimes to figure out what hooks are available, and which one to implement.
In this tutorial we'll look at:
- Different ways to get a list of available hooks
- Where to find the documentation for a hook so you can know if it's the one you want to implement
By the end of this tutorial you should be able to browse a list of hooks and their related documentation.
As a module developer you should define and invoke new hooks in your module in order to allow other developers -- or even future you -- to extend your module's functionality without hacking your module's code. This requires:
- Creating a new, unique, name for your hook
- Providing documentation for your hook
- Invoking the hook at critical points in your code
By the end of this tutorial you should have a better idea of when to define a new hook and know how to invoke a hook from your code.
