I generate a sample Class form (and routing) with the drupal console.

Then, I have my class with some defaults generated methods ; getFormId, buildForm...

When the user go to the url path defined in the routing file, the buildForm method is called for build the the form. I want call another function for check some datas before the buildForm method :

I function like :

function a_check_function_or_method_before_buildForm(...){
    // - Check some datas
    // - If all is ok, the buildForm can be called
    // - Else, if the custom function detect an error, the buildForm isn't called and the user is redirected to an error page

Is it possible to do that ? how can I do that ?

Thank you =)

1 Answer 1


You can do all that inside of buildForm():

use Symfony\Component\HttpKernel\Exception\HttpException;

public function buildForm(array $form, FormStateInterface $form_state) {

  $data = a_check_function_or_method_before_buildForm();

  // throw an exception
  if (empty($data)) {
    throw new HttpException(500, 'No data connection.');

  // or return an empty form with an error message
  if (empty($data)) {
    return $form['#markup'] = '<h1>No data could be collected!</h1>';

  // build the form with $data


Another possibility would be to call first a controller, which then decides what to do, return a form or something else.

  • I want separate check code and build form. Your another possibility seems I'm looking for ! From the controller, how can I build/return the form ? I just need return \Drupal::formBuilder()->getForm(Drupal\example\Form\ExampleForm::class) ? its good ? Sep 18, 2016 at 10:57
  • Yes, if you want you can include a second parameter with your data.
    – 4uk4
    Sep 18, 2016 at 11:15

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