Managing Media in Drupal
CourseTheming Drupal Sites
CourseWeek 1: Setup
CourseWeek 2: Create a New Theme
CourseWeek 3: Add an Asset Library
CourseYAML, which stands for YAML Ain't Markup Language, is a human-readable data serialization format that's been widely adopted in a variety of use cases in Drupal. Anyone wanting to write modules, or themes, for Drupal will need to understand YAML syntax. Even site builders are likely to encounter YAML at least in passing as YAML is the data-serialization format of choice for Drupal's configuration management system. Good thing it's pretty easy to learn even with the most basic of programming backgrounds.
This tutorial will look at the YAML data format and provide examples of how to write and read YAML. Starting with an introduction to the language's syntax and some of the strengths of YAML. Then looking at the difference between scalar data types like strings and integers, and collection data types like lists and associative arrays.
Since YAML in the Drupal world is read into PHP and ultimately becomes a PHP data structure that we can use in our own code we'll also look at how the YAML we write in a .yml file is represented in PHP data types. To do this we'll use the YAML Sandbox module that provides a handy textarea into which we can type YAML and have it parsed into PHP data structures.
Learning objectives
- Explain what YAML is and its strengths as a data serialization format
- Create scalar key/value pairs in YAML
- Create lists, and associative arrays using YAML collections
- Understand how the YAML you write is represented in PHP
Tips
- In Drupal, use the .yml extension and not .yaml
- Ensure your code editing application is configured to use spaces (preferably 2 spaces, as per Drupal coding standards), not the tab character when the TAB key is pressed. If you have tab characters in a YAML file within a Drupal environment, a fatal PHP error will be thrown and you'll see a White Screen of Death (WSOD).
- Copy and paste from an existing YAML file to ensure the formatting is correct, and edit from there.
Additional resources
- http://www.yaml.org
- YAML Sandbox module
- Find other tutorials and external resources related to YAML on our YAML topic page (Drupalize.Me)
Hands-On Theming
GuideTheming Cheat Sheet
GuideLearn Drupal
GuideCustomizing the available regions in your theme is one of the first things you'll do when creating your own themes. Doing so gives you complete control over where content is displayed on the page, and the markup involved. Adding regions to a theme is a two-step process that involves editing your theme's THEMENAME.info.yml file and updating your page.html.twig file.
In this tutorial we'll:
- Declare one or more new regions in our themes THEMENAME.info.yml file.
- Output the content of those regions in our theme via the page.html.twig file.
By the end of this tutorial you should be able to add or edit the regions a theme provides. Also, you'll ensure that blocks placed into regions are displayed by outputting the regions in the page template.
Contributed and custom themes can ship with a thumbnail screenshot that will be used to represent the theme when listing themes in the administration UI.
In this tutorial you'll learn how to:
- Prepare your site for the screenshot
- Create a screenshot of your theme
- Define a screenshot file for your theme in the THEMENAME.info.yml file
Preprocess functions are specially-named functions that can be used to add new variables to a Twig template file. They are commonly used by themes to add new variables based on custom PHP logic and simplify accessing the data contained in complex entity structures. For example: adding a variable to all node.html.twig template files that contains the combined content a couple of specific fields under a meaningful name like {{ call_to_action }}
. Modules use preprocess functions to expose the dynamic data they manage to Twig template files, or to alter data provided by another module based on custom logic.
In this tutorial we'll learn how to:
- Use PHP to perform some complex logic in our theme.
- Store the resulting calculation in a variable.
- Make that variable available to a Twig template file.
Example use cases for adding variables with preprocess functions include:
- Anytime calculating the value to output in a template requires logic more complex than an if/else statement.
- Anytime the desired value requires additional string manipulation beyond what can be easily accomplished using an existing Twig filter or function.
By the end of this tutorial you should be able to expose new variables to a Twig template file by defining a preprocess function in either a module or a theme.