Pimcore\Model\Element\Tag::getTagsForElement PHP Method

    public static function getTagsForElement($cType, $cId)
    {
        $tag = new Tag();
        return $tag->getDao()->getTagsForElement($cType, $cId);
    }

 public function loadTagsForElementAction()
 {
     $assginmentCId = intval($this->getParam("assignmentCId"));
     $assginmentCType = strip_tags($this->getParam("assignmentCType"));
     $assignedTagArray = [];
     if ($assginmentCId && $assginmentCType) {
         $assignedTags = Tag::getTagsForElement($assginmentCType, $assginmentCId);
         foreach ($assignedTags as $assignedTag) {
             $assignedTagArray[] = $this->convertTagToArray($assignedTag, false, []);
         }
     }
     $this->_helper->json($assignedTagArray);
 }