如何捕捉这个PHP / Magento错误：当没有缩略图时，代码中断(How to catch this PHP/Magento error: when no thumbnail, code breaks)

 我有一个自定义的销售点管理员Magento扩展。 我试图在POS页面上的管理产品网格中添加一个缩略图。 当每个产品都有缩略图时，它可以100％正常工作。 但是当产品没有图像时，代码完全被打破。 
 
 如何修改此代码以检查是否存在缩略图，如果不是，则显示占位符（任何替代html都可以）？ 
 
<?php

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

    $cProduct = Mage::getModel("catalog/product");
    $cProductId = $row->getId();
    $cProduct->load($cProductId);  // works for product IDs w/ a thumbnail. Breaks if no thumbnail set.
    // For example, the following line works, loading the thumbnail for the 5533 product for all rows in the grid:  
    // $cProduct->load(5533);

    $cMyUrl = $cProduct->getThumbnailUrl();

    $html = '<img ';
    $html .= 'src="' . $cMyUrl . '"';
    $html .= 'class="grid-image ' . $cProductId . '"/>';

    return $html;      

    }
  }
?>
 
 如果没有缩略图，整个页面会导致错误： http : //www.screencast.com/t/zk6jVChiAC 

I have a custom Point of Sale admin Magento extension. I’m trying to add a thumbnail to the admin product grid on the POS page. It works 100% fine when there is a thumbnail image for every product. But when there’s a product without an image, the code totally breaks.
 
How do I modify this code to check whether there’s a thumbnail, and if not, to display a placeholder (any substitute html is fine)?
 
<?php

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

    $cProduct = Mage::getModel("catalog/product");
    $cProductId = $row->getId();
    $cProduct->load($cProductId);  // works for product IDs w/ a thumbnail. Breaks if no thumbnail set.
    // For example, the following line works, loading the thumbnail for the 5533 product for all rows in the grid:  
    // $cProduct->load(5533);

    $cMyUrl = $cProduct->getThumbnailUrl();

    $html = '<img ';
    $html .= 'src="' . $cMyUrl . '"';
    $html .= 'class="grid-image ' . $cProductId . '"/>';

    return $html;      

    }
  }
?>
 
Whole page results in an error if there’s no thumbnail: http://www.screencast.com/t/zk6jVChiAC 

原文：https://stackoverflow.com/questions/10922011