Cannot send headers; headers already sent

Question

I have used renderer in a file in custom extension for attribute label but getting above error.

my code is below:

<?php 

class Baltech_Stock_Block_Adminhtml_Stock_Renderer_Size extends Mage_Adminhtml_Block_Widget_Grid_Column_Renderer_Abstract
{
   public function render(Varien_Object $row)   
   {
        $value = $row->getData($this->getColumn()->getIndex());
        $attribute = Mage::getModel('eav/config')->getAttribute('catalog_product', 'size');
        $options = array();
        foreach( $attribute->getSource()->getAllOptions(true, true) as $option ) {
          $id = $option['value'];
           if ($id==$value) 
           {
            echo $option['label'];
           }

        }


   }
} 

Answer 1

You can not use echo here. Instead of echo you have to use return from this method :

<?php 
class Baltech_Stock_Block_Adminhtml_Stock_Renderer_Size extends Mage_Adminhtml_Block_Widget_Grid_Column_Renderer_Abstract
{


public function render(Varien_Object $row)   


{
    $value = $row->getData($this->getColumn()->getIndex());
    $attribute = Mage::getModel('eav/config')->getAttribute('catalog_product', 'size');
    $options = array();
    foreach( $attribute->getSource()->getAllOptions(true, true) as $option ) {
      $id = $option['value'];
       if ($id==$value) 
       {
        return $option['label'];
       }

    }
}}