Last updated February 19, 2021
Module Development8.9.x/9.3.x

Sometimes you need to add additional processing of input to forms where your module doesn't implement the form controller. In order to do this you can use the #submit property of the root level $form element, or of a specific button on a form, to add one or more callbacks. These functions, or methods, will be automatically called when the Form API is processing a submitted form and give your custom code an opportunity to do whatever it needs to do.

In this tutorial we'll:

  • Look at alternative ways to affect the submission handling of a form like #submit callbacks

By the end of this tutorial you should know how to add a #submit callback to an entire form, or a specific button in a form.