Contao Summit 2026 in Leipzig 15th and 16th October

prepareFormData

The prepareFormData hook is triggered after a form has been submitted, but before it is processed. It passes the form data array, the form labels array and the form object as arguments and does not expect a return value. This way the data can be changed or extended, prior to execution of actions like email distribution or data storage.

Parameters

  1. array $submittedData

    The user input from the form.

  2. array $labels

    The field labels of the form.

  3. array $fields

    The fields for this form as an array of \Contao\Widget instances.

  4. \Contao\Form $form

    The form instance.

Example

​
// src/EventListener/PrepareFormDataListener.php
namespace App\EventListener;

use Contao\CoreBundle\DependencyInjection\Attribute\AsHook;
use Contao\Form;

#[AsHook('prepareFormData')]
class PrepareFormDataListener
{
    public function __invoke(
        array &$submittedData, 
        array $labels, 
        array $fields, 
        Form $form, 
        array &$files
    ): void
    {
        
        // Add a custom file as attachment
        $files[] = [
            'name' => 'MyAttachmentFileName.txt',
            'tmp_name' => 'path/to/MyAttachmentFileName.txt',
            'type' => 'text/plain',
        ];
    
        // This calculates a deadline from a given timestamp
        // and stores it as deadline in $submittedData.
        $submittedData['deadline'] = strtotime('+1 hour', $submittedData['tstamp']);
    }
}
// src/EventListener/PrepareFormDataListener.php
namespace App\EventListener;

use Contao\CoreBundle\DependencyInjection\Attribute\AsHook;
use Contao\Form;

#[AsHook('prepareFormData')]
class PrepareFormDataListener
{
    public function __invoke(array &$submittedData, array $labels, array $fields, Form $form): void
    {
        // This calculates a deadline from a given timestamp
        // and stores it as deadline in $submittedData.
        $submittedData['deadline'] = strtotime('+1 hour', $submittedData['tstamp']);
    }
}

References