Add throbber in entity browser widget during submit

I have the same problem.

Drupal Core 8.4.0.

is there a solution?

I am using Modal as display, and Acquia DAM as widget plugin. I too want this feature.

I was partially able to fix it by adding an ajax callback inside the form builder getForm(). The idea is to make use of the ajax throbber and the wait message "Please wait..." and make the end user understand that a process is in progress.

  public function getForm(array &$original_form, FormStateInterface $form_state, array $additional_widget_parameters) {
    // code..
    $form['actions']['submit']['#ajax'] = [
      'callback' => '\Drupal\media_acquiadam\Plugin\EntityBrowser\Widget\Acquiadam::ajaxSubmit',
    ];
  }

  public function ajaxSubmit(array &$form, FormStateInterface $form_state) {
    $response = new AjaxResponse();
    $response->addCommand(new CloseModalDialogCommand());
    return $response;
  }

the problem is it does not closes the modal. I am figuring out if there is a better way to do this.

I have managed to show a progress bar when the form is submitted.

It works if you have selected an existing media entity, but breaks when a new entity is selected.

I managed to find the reason. The patch is fine. I was echo-ing the time it takes for fetching the resource from the external service (WebDAM), and the output was getting appended to the `JSONResponse` and it was messing the whole thing.

Decided to move the progress type to custom widget.

The progress type can be modified like this #3005892-2: Show infinite progress bar during asset download

I have used the ajax callback to show status messages in the form. This implementation can be improved.

Making sure that IFrame display does not override passed AjaxResponse.