The Form API is a Drupal powerful system to create all kind of forms. However, given its complexity, it may be hard to completely understand it and is easy to end up fighting against it when building complex forms.

The existent documentation is good but there's a lack of a general but detailed picture of the whole form request flow from the form building to the end submission, including all possible rebuilds due to validation errors, requests in a multi-step form or other form actions.

This talk will explain all the phases of a form request flow, from the initial build, alterations, send to client, form rebuild (when and why), to cache mechanisms, handlers execution or how AJAX requests are handled.

Attendees should have basic technical knowledge about involved mechanisms (HTTP requests, Render Arrays, PHP POO and form basics). The session will try to give a general knowledge about the complete life-cycle of a form request detailing its key aspects. After this session, you'll understand how the Form API and Drupal handle forms and you'll be more confident when you need to alter, extend or use forms in a complex or advanced fashion.

Presentation: https://rsanzante.github.io/drupalconprague-2022-form-api-workflow/