Drupal's Field API provides a powerful system for defining, managing, and storing various types of structured data fields on entities, allowing for flexible content modeling and customization.
In this course you’ll learn the foundational concepts and components of the Field API, including how to define and manage field instances, field types, form widgets, and display formatters. The course will cover how to use the Field API to create custom fields, interact with field data programmatically, and alter field behavior using hooks. Additionally, you will explore the differences between base fields and user-defined fields, and how to leverage the Field API to build flexible and extensible data models in Drupal.
Key topics
- Overview of Field API components: field types, widgets, and formatters
- Creating and managing custom fields
- Working with field data in code
- Using Field API hooks to alter field behavior
- Differences between base fields and user-defined fields
- Practical examples and use cases for field widgets and formatters
- Advanced field configurations and customizations
Field API Overview
FreeIf you've ever created or edited a piece of content on a Drupal site you have already interacted with the Field API. The Field module (along with its user interface counterpart) is responsible for providing the forms and data components used to build up the content model that make up a Drupal site. Understanding how Drupal fields work and how they're constructed via the Field API is an important part of understanding how Drupal works.
In this tutorial, we're going to look at the main components that make up the Field API at a high level. We'll see how the Field UI module exposes the field types included in core. We'll also look at the three main pieces that compose fields: types, widgets and formatters.
Drupal's field system provides us with a flexible system of adding different types of discrete data to content types. This enables us to create rich content models. The Field API allows us to define these distinct field types by creating a new plugin. These plugins specify a FieldType annotation. In this tutorial, we'll look at these annotations in detail. We'll look at the implementations of field types from Drupal core. Also, we'll see what a new custom field type would look like.
By the end of this tutorial, you should be able to:
- Understand how field type definitions are created and exposed to Drupal
- Identify the various field types provided by Drupal core
- Understand the requirements for providing a specification for a new field type
Once we've explored the various field types provided by Drupal core, the next component of the Field API to explore is field widgets. Field widgets define how the data structure of the field is displayed on an edit form. When content editors interact with your field type they will be doing so via the field widget you provide. In this tutorial, we'll take a look at the field widgets provided by Drupal core, the plugin type required to define our own custom widget and how we can define multiple widget options for a single field type.
By the end of this tutorial, you should be able to:
- Understand where field widgets fit into the overall Field API
- Implement a custom field widget to support a particular field type
Of the 3 main components of the field system -- types, widgets and formatters -- only 1 has an impact on the actual display of content for end users: field formatters. Field formatters are responsible for taking the data stored by a field and transforming it into the markup that is sent to the browser when an end user views your site.
In this tutorial we'll:
- Look at the role field formatters play in the Field API
- Identify the main components that make up a field formatter
By the end of this tutorial you should be able to define the role of a field formatter plugin.
Field formatters are responsible for taking the data stored by a field and transforming it into what a vistor sees. We can define new field formatters to output data for new field types or to provide alternative formatting options for existing field types. Creating a field formatter plugin is a common task for Drupal developers.
In this tutorial we'll:
- Define a new background color field formatter that uses the string stored by our field_example_rgb field type as the background color of the output.
- Make it possible for site builders to toggle on or off a feature that automatically adjusts the foreground text color of the output.
By the end of this tutorial you should be able to define a new custom field formatter plugin with settings that a site administrator can configure.
Drupal's Field API specifies the implementation details for field types, widgets and formatters. It also provides several hooks that allow custom code to alter these implementation details. In this tutorial we'll take a look at these Field API hooks and see how they can be used to change field types, widgets and formatters.
By the end of this lesson, you should be able to:
- Idenfity existing Field API hooks for manipulating field behavior
- Understand the proper method for changing the behavior of a field type, widget or formatter
- Know where to find the documentation for these API functions, and how to find their implementations
