Goal: Print/dump $formState values to debug

I am altering a form and the functionality works:

$form['elements']['location']['deparment']['#ajax'] = [
  'callback' => 'myAjaxCallback',
  'event' => 'change',
  'progress' => [
    'type' => 'throbber',
    'message' => t('Verifying entry...'),

but what I want is to be able to print out $formState in myAjaxCallback

function myAjaxCallback(array &$form, FormStateInterface $formState){
 $response = new AjaxResponse();
 print_r($formState); //I've tried, with memory_limit=-1 . it just hangs
 dump($formState); //gives me File upload exceeds. This comes from issue with using dump in ajax

 return $response

I have also read https://www.drupal.org/docs/drupal-apis/javascript-api/ajax-forms and tried their Debugging AJAX Callback Functions, which has:

$response = new AjaxResponse();
$debugOut = @Kint::dump($formState); //but this uses dump too, which gives me ajax errors

so dd($formState->getValues()); kind of works. This is what it shows me. So, as you can see, I can now see the variables. It's not the best, but readable.

enter image description here

whereas if I go to [website]/webform?ajax_form=1 , it's not even readable.

enter image description here

I am running out of ideas to be able to debug the variable $formState .

  • 4
    Have you tried using xdebug?
    – sonfd
    Commented Aug 25, 2020 at 18:47
  • @sonfd I have not. I'll give it a go Commented Aug 25, 2020 at 20:26
  • @sonfd can you submit your comment as the solution. Just installed Xdebug for phpstorm on XAMP, it's amazing! exactly what I've always needed! Commented Aug 26, 2020 at 19:56
  • Armando Silva - go ahead and add it as an answer and feel free to add any helpful details you can about setting it up.
    – sonfd
    Commented Aug 26, 2020 at 20:53

1 Answer 1


@sonfd Xdebug helps print out the values beautifully. No more print_r() or kint() errors.

enter image description here

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