Maybe you consider yourself a Drupal site builder or front-end developer. As soon as someone starts talking object-oriented PHP, you run for the hills. This makes the prospect of building a module for Drupal 8 scary. But on many projects, site building and theming can get you 95% of the way there, and you just need a tiny bit of code to get the job done. In this session, I'll walk through a couple simple examples of code you can add to your project to fill in these types of gaps. We'll cover some really essential concepts and code snippets that will help you understand how to read Drupal 8 code and write that 'glue module' to get the website finished.

1. evolvingweb.ca @evolvingweb
Dipping Your Toe into Drupal
8 Module Development
WITH SUZANNE DERGACHEVA

2. • Co-founded Evolving Web in
2007
• Experienced Drupal themer,
developer, project lead
• Loves teaching DrupalSuzanne Dergacheva
CO-FOUNDER AND FRONT-END LEAD

3. Creating great websites
with Drupal
TRAINING WEB DEVELOPMENT WEB CONSULTING

4. Some of our happy clients

5. Should I Create a Module?
PROS
• You get a flexible solution
• Might be simpler than installing
a complex module
CONS
• Takes time/skills to develop
• You have to maintain the code
• Can introduce bugs

6. Simple Module Examples
• Change a form
• Add a programmatic block
• Add a programmatic page
• Add a menu link
• Create a field formatter
• Add custom validation

7. Before You Start
• Use the local.settings.php file and development.services.yml files
(https://www.drupal.org/node/2598914)
• Enables errors and warnings
• Disables some caching
• Disables aggregation of CSS/JS
• Install the Devel module
• Make sure your editor has syntax highlighting set up

8. Step 1: Research
• Is there already a module that does this?
• If not, is there something similar. Look for an example:
• Drupal core
• Contrib modules
• Examples module
• Try and find the code that does the thing you want
• Figure out how it integrates with Drupal (usually a hook or a Class)

9. Step 2: Create the Scaffolding
• Use the Drupal Console to write the scaffolding code or use
examples from other modules to see what structure you need
• Create a module folder, and an .info.yml file
• Then, add a Class or hook to your module
drupal generate:module
drupal generate:controller

10. Step 3: Fill in the Custom Code
• Write the logical part of your code that does the custom work
• Look for exmaples of what you’re trying to do
• You can copy and paste code snippets
• … But make sure you read/understand each line of code!

11. Step 4: Testing
• Easy to forget to test when you’re doing something simple
• QA Tips:
• Read error messages
• Make sure you understand what you’re testing (what is supposed
to change on the site)
• Also test that your code doesn’t break other use cases. You might
need to add an ‘if’ statement

12. Essential Terminology
• Yml - File format used to define modules/theme, permissions, paths,
menu items, and exported configuration
• Class - Group of properties and methods that define an object. Used
to extend parts of Drupal so you can create your own Forms, Blocks,
Fields, Entities, Webform Elements, etc.
• Plugin - Class that is ‘discoverable’ by Drupal. Examples: Blocks,
Fields
• Hook - Function that allows you to alter how something works in
Drupal. Examples: altering forms, emails, adding things to cron

13. Let’s Build a Module

14. Real Example Module

15. Link to the Edit Account Page

16. Link to the Edit Account Page
• Define a new path
• The path points to a Controller
• The controller redirects you to the path /user/[uid] but fills in the uid
of the current User
drupal generate:controller
drupal generate:module

17. Changing a Form

18. Changing a Form
• Find the form ID
• Implement hook_form_alter
• Add/remove/update elements of the form
• Use this reference: https://api.drupal.org/api/drupal/elements/8.2.x
drupal generate:form:alter
drupal generate:module

19. Useful Code Snippets
http://bit.ly/d8-snippets

20. Next Steps
• Drupal Docs for Creating Custom Modules: https://www.drupal.org/
docs/8/creating-custom-modules
• Try this tutorial: https://www.drupal.org/docs/8/creating-custom-
modules/a-hello-world-custom-page-module
• Download the Examples module: http://drupal.org/project/examples

21. Upcoming Drupal
Trainings
MAY 7-11, IN-PERSON
Drupal 8 Training in Princeton NJ
FEB 5-8, ONLINE
Drupal 8 Module Development
FEB 20-23, ONLINE
Migrate to Drupal 8
MARCH 1-2, ONLINE
Drupal 8 Site Building
MARCH 12-15, ONLINE
Drupal 8 Theming
evolvingweb.ca/training
training@evolvingweb.ca

22. @suzanne_kennedy
evolvingweb.ca @evolvingweb
Thank you!