Create a custom form with Form API in Drupal 8
Creating forms is part of the day to day live of a Drupal programmer. Forms are represented as nested arrays in both Drupal 7 and Drupal 8. But they are different in that in Drupal 7 you define your form arrays in functions and in Drupal 8 you create a form class.
In this post we’ll create a custom form with two fields, a text field and a checkbox field, we’ll validate those fields, display them in a message and finally redirect the user to the home page.
You can find the code of this module here.
Here is a screenshot of the form: