Module Development

Form API Life Cycle for Drupal 8, 9, 10, and 11

This tutorial will help you understand the complete life cycle of a Drupal form: receiving the request from a browser, displaying a page with a form, rendering the form as HTML, handling the submitted form, validating input, handling errors, and processing data. We'll point out the common places that module developers might want to inject additional functionality into the process. And we'll link to tutorials with more details about each integration point in a form's life cycle.

In this tutorial, we'll:

  • List the steps of the life cycle of a Drupal form.
  • Describe how Drupal determines which form to display, and which form handles an HTTP POST request.
  • Understand the role of FormStateInterface in the life cycle of a form.

By the end of this tutorial, you should have a solid understanding of the life cycle of a form within Drupal.