For running J!5.1 you must https://fabrikar.com/forums/index.php?wiki/update-from-github/ or include the new file manually https://fabrikar.com/forums/index.php?threads/joomla-5-1-and-fabrik-cannot-find-files-error.54473/post-285151 See also Announcements
Please see our announcement here.
$app = JFactory::getApplication();
$id= $app->input->getString('emaillist___dbconnection');
$this->getFormModel->getElementData('emaillist___dbconnection');
protected function getPhpOptions()
{
$params = $this->getParams();
$pop = $params->get('dropdown_populate', '');
if ($pop !== '')
{
$w = new FabrikWorker;
$pop = $w->parseMessageForPlaceHolder($pop, $this->getFormModel()->getData());