Add custom-field to product /listing_img_title.php

-- HikaShop version -- : 2.6.4
-- Joomla version -- : 3.6.5
-- PHP version -- : 5.5

I want to add custom-filed display in listing_img_title.php
I have added the following code in php , but can't display $this->element->myfield , always empty

what else code do I need to add!!



foreach ($this->fields as $fieldName => $oneExtraField) {
$value = '';
if(empty($this->element->$fieldName) && !empty($this->element->main->$fieldName))$this->element->$fieldName = $this->element->main->$fieldName;
if(isset($this->element->$fieldName))
$value = trim($this->element->$fieldName);
if(!empty($value)){
$hide_specs = 0;
break;
}
}