This action is called once a form has been submitted and the handler starts handling the submission.
It is passed two parameters
- $form – the form configuration array
- $process_id The unique process ID for this submission. This value will be empty if this is the first submission attempt, not a re-submission after an error.
Where Does This Code Go?
When using WordPress hooks to customize Caldera Forms or other plugins you should not modify the plugin files, or you will lose your changes when you update the plugin. Instead you should create a small plugin to hold the custom code. It's easy, learn how here.
Technically you can add the custom code to your theme's functions.php, but then you will not be able to change your theme and keep these customizations.