I have a file that is generated when an AJAX button is clicked. I want to immediately have a file download prompt come up. The file is being generated and has the correct data in the file. I just don’t know how to force the download prompt to come up.

Edit#1

I have updated the generateCSV() code to include:

$response = new BinaryFileResponse($path . $filename); $response->setContentDisposition(   ResponseHeaderBag::DISPOSITION_ATTACHMENT,   $filename );  $form_state->setResponse($response); 

This is not invoking a download.

AJAX Button

$form['comp_card_dl'] = [   '#type' => 'button',   '#value' => $this->t('Download'),   '#ajax' => [     'callback' => '::generateCSV',     'progress' => [       'type' => 'throbber',     ],   ],   '#name' => 'comp_card_download', ]; 

CSV File Creation

public function generateCSV($form, FormStateInterface $form_state) {   $trigger = $form_state->getTriggeringElement();   if ($trigger['#name'] == 'gift_card_download') {     $filename = $form['#gift_card_filename'];     $data = $form['#gift_card_data'];   }   else if ($trigger['#name'] == 'comp_card_download') {     $filename = $form['#comp_card_filename'];     $data = $form['#comp_card_data'];   }    $path = Drupal::service('file_system')->realpath(file_default_scheme() . "://") . '/';   $csv = fopen($path . $filename, 'w');    foreach ($data as $id => $value) {     array_unshift($value, $id);     fputcsv($csv, $value);   }    fclose($csv);    $response = new BinaryFileResponse($path . $filename);   $response->setContentDisposition(     ResponseHeaderBag::DISPOSITION_ATTACHMENT,     $filename   );    $form_state->setResponse($response); }