Form.submission.creating

Fired when a form is submitted, but before it is saved. Allows you to stop or modify the submission.

The Submission object will get passed through.

To modify the submission, return an array with a submission key containing the modified Submission object.

To stop the submission and display errors, return an array with an errors key containing an array of error messages.

use Statamic\Contracts\Forms\Submission;

public $events = ['Form.submission.creating' => 'handle'];

public function handle(Submission $submission)
{
    return [
        'submission' => $submission,
        'errors' => []
    ];
}

To stop the submission, but make it appear as though it was successful (for example, a Honeypot spam technique) you may throw a Statamic\Exceptions\SilentFormFailureException.