how to prerender/preprocess the data before displaying in custom admin module grid?

Question

i have a custom admin module will print some data

$this->addColumn('product_old_values', array(
 'header' => Mage::helper('adminlog')->__('product_old_values'),
 'align' =>'left',
 'width' => '20%',
 'index' => 'product_old_values',
)); 

since product_old_values is a serialized array (a long string), how can i run unserialize(product_old_values) before displaying into a grid?

Answer 1

render the column by below code

$this->addColumn('product_old_values', array(
 'header' => Mage::helper('adminlog')->__('product_old_values'),
 'align' =>'left',
 'renderer' => 'Namespace_Modulename_Block_Adminhtml_Gridrender',
 'width' => '20%',
 'index' => 'product_old_values',
)); 

FOR RENDERING

class Namespace_Modulename_Block_Adminhtml_Gridrender extends Mage_Adminhtml_Block_Widget_Grid_Column_Renderer_Abstract
 {
 public function render(Varien_Object $row)
 {
 }
 }

for doing in grid class

 $this->addColumn('product_old_values', array(
 'header' => Mage::helper('adminlog')->__('product_old_values'),
 'align' =>'left', 
 'width' => '20%',
 'index' => 'product_old_values',
 'frame_callback' => array($this, 'callback_image')
 ));
public function callback_image($value)
 {
 //write your code
 }

• hkguile: is it a must to open another class? can i do it in grid class?
• Qaisar Satti: you can do it with 'frame_callback' => array($this, 'callback_image') public function callback_image($value) { $width = 20; $height = 20; return "<img src='".Mage::getBaseUrl('media').$value."' width=".$width." height=".$height."/>"; } i used it for image
• Qaisar Satti: i update the answer..
• Dhaval Solanki: @QaisarSatti can we return custom HTML in callback_image() method ?
• Qaisar Satti: @dhavalsolanki yes