Drupal 8 Custom Module

AddForm

• use FormBase
• change declaration buildForm, submitForm, validateForm (form_state is an object and no longer an array)
• no arguments passed by the buildForm declaration

DeleteForm

• getCancelUrl in stead of getCancelRoute
• change declaration buildForm, submitForm, validateForm (form_state is an object and not array)
• no arguments passed by the buildForm declaration

AdminController

• content function returns array of 2 elements (text markup and a table)
• l-function has changed. 1 argument is now a URL object

Local Tasks

• use .links.task.yml
• use base_route: system.admin_content