Extending Mage_Adminhtml_Block_Catalog_Product_List

Question

I'm trying to extend the Action List. I've looked for rewrite conflicts with the many rewrite tools. I'm just not seeing it. Here is my code.

<?php

 class MDN_BarcodeLabel_Block_Product_List extends
 Mage_Adminhtml_Block_Catalog_Product_List {

     protected function _prepareMassaction() {


         parent::_prepareMassaction();

         // Append new mass action option
         $this->getMassactionBlock()->addItem(
             'BarcodeLabel',
             array('label' => $this->__('Print barcode labels'),
                   'url'   => $this->getUrl('adminhtml/BarcodeLabel_Admin/printSelectedProductLabel')
             )
         );

     }

 }

 ?>

Here rewrite script below show it being listed by itself. Here is the Observer.php. I have everything working fine on a clean install, but I can't seem to find the conflict anywhere. There is ACL built in, but that is working perfect.

public function addMassAction($observer) {
        $block = $observer->getEvent()->getBlock();
        if (get_class($block) == 'Mage_Adminhtml_Block_Widget_Grid_Massaction'
                && $block->getRequest()->getControllerName() == 'catalog_product') {

            $admin_user_session = Mage::getSingleton('admin/session');
            $adminuserId = $admin_user_session->getUser()->getUserId();
            $role_data = Mage::getModel('admin/user')->load($adminuserId)->getRole();
            $roleIdUser = $role_data->getRoleId();

            $barcodeprofiles = Mage::getModel('barcodeprofile/barcodeprofile')->getCollection()
                ->addFieldToFilter('status', 1);
            $arrayBarcode = array();
            foreach($barcodeprofiles as $data) {
                $arrayRole = explode(',', $data->getRole());
                if(in_array($roleIdUser, $arrayRole)) {
                    $arrayBarcode[$data->getId()] = $data->getProfile();
                }
            }

            $block->addItem('BarcodeLabel', array(
                'label' => Mage::helper('BarcodeLabel')->__('Print barcode labels'),
                'url' => Mage::app()->getStore()->getUrl('adminhtml/BarcodeLabel_Admin/printSelectedProductLabel'),
                'additional' => array(
                    'visibility' => array(
                        'name' => 'barcode_profile',
                        'type' => 'select',
                        'class' => 'required-entry',
                        'label' => Mage::helper('catalog')->__('Barcode Profile'),
                        'values' => $arrayBarcode
                    )
                )
            ));

If you interested here is the config.xml. Sorry about the length. ...

    <global>

        <helpers>
            <BarcodeLabel>
                <class>MDN_BarcodeLabel_Helper</class>
            </BarcodeLabel>
        </helpers>

        <blocks>
            <BarcodeLabel>
                <class>MDN_BarcodeLabel_Block</class>
            </BarcodeLabel>


            <adminhtml>
                <rewrite>
                    <catalog_product_list>MDN_BarcodeLabel_Block_Product_List</catalog_product_list>
                </rewrite>
            </adminhtml>

        </blocks>

        <models>
            <BarcodeLabel>
                <class>MDN_BarcodeLabel_Model</class>
                <resourceModel>BarcodeLabel_mysql4</resourceModel>
            </BarcodeLabel>

           <BarcodeLabel_mysql4>
                <class>MDN_BarcodeLabel_Model_Mysql4</class>
                <entities>
                    <List>
                        <table>barcode_label_list</table>
                    </List> 
                    <ProductVarchar>
                        <table>catalog_product_entity_varchar</table>
                    </ProductVarchar>
                </entities>
            </BarcodeLabel_mysql4>

            <AdvancedStock>
                <rewrite>
                    <Pdf_BarcodeLabels>MDN_BarcodeLabel_Model_Pdf_Labels</Pdf_BarcodeLabels>
                </rewrite>
            </AdvancedStock>

        </models>

        <resources>
            <BarcodeLabel_setup>
                <setup>
                    <module>MDN_BarcodeLabel</module>
                    <class>Mage_Catalog_Model_Resource_Eav_Mysql4_Setup</class>
                </setup>
                <connection>
                    <use>core_setup</use>
                </connection>
            </BarcodeLabel_setup>
            <BarcodeLabel_write>
                <connection>
                    <use>core_write</use>
                </connection>
            </BarcodeLabel_write>
            <BarcodeLabel_read>
                <connection>
                    <use>core_read</use>
                </connection>
            </BarcodeLabel_read>
        </resources>

        <events>
            <model_save_after>
                <observers>
                    <BarcodeLabel>
                        <type>singleton</type>
                        <class>BarcodeLabel/observer</class>
                        <method>model_save_after</method>
                    </BarcodeLabel>
                </observers>
            </model_save_after>
        </events>
    </global>

    <adminhtml>

        <translate>
            <modules>
                <MDN_BarcodeLabel>
                    <files>
                        <default>MDN_BarcodeLabel.csv</default>
                    </files>
                </MDN_BarcodeLabel>
            </modules>
        </translate>

        <layout>
            <updates>
                <BarcodeLabel>
                    <file>BarcodeLabel.xml</file>
                </BarcodeLabel>
            </updates>
        </layout>

        <acl>
            <resources>
                <admin>
                    <children>
                        <system>
                            <children>
                                <config>
                                    <children>
                                        <barcodelabel module="BarcodeLabel">
                                            <title>Barcode label</title>
                                        </barcodelabel>
                                    </children>
                                </config>
                            </children>
                        </system>
                    </children>
                </admin>
            </resources>
        </acl>

        <events>
            <core_block_abstract_prepare_layout_before>
                <observers>
                        <BarcodeLabel_core_block_abstract_prepare_layout_before>
                            <class>BarcodeLabel/observer</class>
                            <method>addMassAction</method>
                        </BarcodeLabel_core_block_abstract_prepare_layout_before>
                </observers>
            </core_block_abstract_prepare_layout_before>
        </events>

    </adminhtml>

    <frontend>
        <secure_url>
            <BarcodeLabel>/BarcodeLabel/</BarcodeLabel>
        </secure_url>
        <routers>
            <BarcodeLabel>
                <use>standard</use>
                <args>
                    <module>MDN_BarcodeLabel</module>
                    <frontName>BarcodeLabel</frontName>
                </args>
            </BarcodeLabel>
        </routers>
    </frontend>

    <admin>
        <routers>
            <adminhtml>
                <args>
                    <modules>
                        <BarcodeLabel before="Mage_Adminhtml">MDN_BarcodeLabel_Adminhtml</BarcodeLabel>
                    </modules>
                </args>
            </adminhtml>
        </routers>
    </admin>
...

Answer 1

UPDATE

As per @Digital pointed, is there class called Mage_Adminhtml_Block_Catalog_Product_List presents? I believe there is not. Please check which class are you trying to extend. But yes, extending approach is the same as below.

First approach via extension

If you have created an extension for this then you must have this in your config.xml in order to extend it

<global>
   <blocks>
        .................
         <adminhtml>
            <rewrite>
                <catalog_product_list>MDN_BarcodeLabel_Block_Product_List</catalog_product_list>
            </rewrite>
        </adminhtml>
   </blocks>
</global>

*You must have List.php in this format:

app/code/community[or local]/MDN/BarcodeLabel/Block/Product/List.php

Second approach via local folder

If you don't want to create an extension for this then just place List.php file in following directory.

app/code/local/Mage/Adminhtml/Block/Catalog/Product

This should work.

UPDATE

Sometime your extended class doesn't come to effect due to other extension extending same class.

To check which other extension extending what, create this file in your root

<?php 
$folders = array('app/code/local/', 'app/code/community/');//folders to parse
$configFiles = array();
foreach ($folders as $folder){
    $files = glob($folder.'*/*/etc/config.xml');//get all config.xml files in the specified folder
    $configFiles = array_merge($configFiles, $files);//merge with the rest of the config files
}
$rewrites = array();//list of all rewrites

foreach ($configFiles as $file){
    $dom = new DOMDocument;
    $dom->loadXML(file_get_contents($file));
    $xpath = new DOMXPath($dom);
        $path = '//rewrite/*';//search for tags named 'rewrite'
        $text = $xpath->query($path);
        foreach ($text as $rewriteElement){
            $type = $rewriteElement->parentNode->parentNode->parentNode->tagName;//what is overwritten (model, block, helper)
            $parent = $rewriteElement->parentNode->parentNode->tagName;//module identifier that is being rewritten (core, catalog, sales, ...)
            $name = $rewriteElement->tagName;//element that is rewritten (layout, product, category, order)
            foreach ($rewriteElement->childNodes as $element){
                $rewrites[$type][$parent.'/'.$name][] = $element->textContent;//class that rewrites it
            }
        }
}
echo "<pre>";print_r($rewrites);

And call it from browser. Reference

If you find your class is extended by other extension then you have two choice, one is to merge one of the file (which is hard to handle in future) and other is create dependancy one in other.

Answer 2

I'm not aware of such class Mage_Adminhtml_Block_Catalog_Product_List I assume you're referring to Mage_Adminhtml_Block_Catalog_Product_Grid right ?

In that case, a safer way of doing it compared to rewrite the entire block is to use event observers in a custom module:

In your config.xml add the following code

    <adminhtml>
        <events>
            <!-- event triggered after the original massaction items are added -->
            <adminhtml_catalog_product_grid_prepare_massaction>
                <observers>
                    <massaction_add>
                        <type>singleton</type>
                        <class>extension/observer</class>
                        <method>addAction</method>
                    </massaction_add>
                </observers>
            </adminhtml_catalog_product_grid_prepare_massaction>
        </events>
    </adminhtml>

Then create a Model/Observer.php file with the following content

<?php

class Vendor_Extension_Model_Observer
{
    /**
     * Add a new massaction
     * @param Varien_Event_Observer $observer
     */
    public function addAction(Varien_Event_Observer $observer)
    {
        $block = $observer->getEvent()->getBlock();

        $block->getMassactionBlock()->addItem('BarcodeLabel',
             array('label' => $this->__('Print barcode labels'),
                   'url'   => $this->getUrl('adminhtml/BarcodeLabel_Admin/printSelectedProductLabel')
             ));
    }
}

Be sure to replace extension with your extension name in the code I provided for config.xml as well as replacing the Observer.php class name with your module name and vendor.