Joomla4 error: class to undefined method

Question

While this code working in Joomla 3x with PHP 8, it is not working in Joomla 4x -- it is showing error class to undefined method

public function display($tpl = null)
{
    $app = Factory::getApplication();
    $db  = Factory::getDBO();
    $user = Factory::getUser();
    $this->state = $this->get('State');
    $this->item = $this->get('Data');
    $this->params = $app->getParams('com_car');

    $model      = $this->getModel();
    $modelcar   = $this->getModel( 'product' );
        
    $id  = $app->input->get('id','','default','int');
    $vid = $app->input->get('vid','','default','int');
        
    $prodDet = $modelcar->loadProduct($id,$vid);
    $this->assignRef('prodDet'  , $prodDet);
        
    $CatName = $modelcar->getCatName($id);
    $this->assignRef('CatName'  , $CatName);

Here this line is the problem area:

$prodDet = $modelcar->loadProduct($id,$vid);
$this->assignRef('prodDet'  , $prodDet);
    
$CatName = $modelcar->getCatName($id);
$this->assignRef('CatName'  , $CatName);

Answer 1

Joomla\CMS\MVC\View\HtmlView::assignRef() has been removed. Use native PHP syntax:

$this->CatName = &$CatName;

In most cases you probably don't even need to assign by reference. So use this instead:

$this->CatName = $CatName;