如何在magento 1.8.1中添加产品图片销售订单网格？

Question

如何在magento 1.8.1中添加产品图片销售订单网格？  我尝试下面的代码，但显示空白图像，我想在这里出售哪种产品？

public function callback_thumbnail($value, $row, $column, $isExport) {
  $product_id = $value;
   $product = Mage::getModel('catalog/product')->load($product_id);
   $url = Mage::helper('catalog/image')->init($product,     'thumbnail')>resize(70,70);
    return "<img src='$url' />";
     }  
     $this->addColumn('entity_id', array(
         'header' => Mage::helper('catalog')->__('Thumbnail'),
          'index' => 'entity_id',
          'frame_callback' => array($this, 'callback_thumbnail')
       ));

Answer 1

我用这个扩展解决了这个问题 http://www.magentocommerce.com/magento-connect/advanced-ordergrid-with-images.html