Write a file, after them redirect

Question

Sorry for the newbie question...

I modified CRM_Contact_Form_Task_Label class, to create my own Task. It creates necessary data for printing membership cards. If a contact has all necessary data, then these are printed to a file, if not, the contact should be shown as result of a Custom Search.

I can't figure out why, but this code doesn't shows up the file, only redirects the page. File is shown up when I add exit; after the $fileReady = self::createMembershipCard($rows); row.

Please advise me, how can I show up the file and then redirect the page.

Thank you!

    function postProcess($params = NULL) {

        [...]

        $fileReady = FALSE;
        $fileReady = self::createMembershipCard($rows);
        if($fileReady) {
            $csvListOfIds = implode(",", $failed);
            CRM_Utils_System::redirect( CRM_Utils_System::url('civicrm/contact/search/custom', "reset=1&force=1&csid=19&cid={$csvListOfIds}"));
        }
     }

  /**
   * Create export file for Membership Cards.
   *
   * @param array $contactRows
   *   Associated array of contact data.
   */
    public function createMembershipCard(&$contactRows) {
        header('Content-Type: text/csv; charset=utf-8');
        header('Content-Disposition: attachment; filename=data.txt');

        $output = fopen('php://output', 'w');
        
        if(sizeof($contactRows) != 0) {
            foreach($contactRows as $item) {
                $toOutput = $item['display_name'].';'.date('Y.m.d.').';2099.21.31.'.PHP_EOL;
                fwrite($output, $toOutput);
            }
        }
        fclose($output);
        
        return TRUE;
    }

Answer 1

It's not possible in a web browser application / HTTP to do a download and then redirect.

Since you're passing the list of cids in the redirect url, what you can do is in buildform add a link on the page to a download that uses the list of cids if present. Then add a "page" (civix generate:page) in your extension that responds to that link and does the same thing your createMembershipCard() function does.

e.g. civix generate:page CRM_Myextension_MembershipCard civicrm/myextension/membershipcard

and then in buildForm you'd do something like

$cids = CRM_Utils_Request::retrieve('cids', 'String', $this);
$url = CRM_Utils_System::url('civicrm/myextension/membershipcard', "reset=1&cids={$cids}");
$form->assign('url', $url);
CRM_Core_Region::instance('page-body')->add(array(
    'template' => 'CRM/Myextension/MembershipCard.tpl',
  ));

and in MembershipCard.tpl you'd have a link like <a href="{$url}">{ts}Download membership card{/ts}</a>

and in CRM_Myextension_MembershipCard::run you do the same thing as createMembershipCard().