Magento – magento admin product grid add category filter to admin grid without adding column

You have to create an extension to display category in product grid. Please create following files and it will work for you:

Create a new file on app/code/local/SoftProdigy/AdminGridCategoryFilter/Block/Catalog/Product/Grid/Render/Category.php location and add following code:

<?php
class SoftProdigy_AdminGridCategoryFilter_Block_Catalog_Product_Grid_Render_Category extends Mage_Adminhtml_Block_Widget_Grid_Column_Renderer_Abstract
{
    public function render(Varien_Object $row)
    {
        $product = Mage::getModel('catalog/product')->load($row->getEntityId());
        $cats = $product->getCategoryIds();
        $allCats = '';
        foreach($cats as $key => $cat)
        {
            $_category = Mage::getModel('catalog/category')->load($cat);
            $allCats.= $_category->getName();
            if($key < count($cats)-1)
                $allCats.= ',<br />';
        }
        return $allCats;
    }

}

Create a new file on app/code/local/SoftProdigy/AdminGridCategoryFilter/etc/config.xml location and add following code:

<?xml version="1.0"?>
<config>
    <modules>
        <SoftProdigy_AdminGridCategoryFilter>
            <version>0.0.0.1</version>
        </SoftProdigy_AdminGridCategoryFilter>
    </modules>
    <global>
        <models>
            <admingridcategoryfilter>
                <class>SoftProdigy_AdminGridCategoryFilter_Model</class>
            </admingridcategoryfilter>
        </models>
        <helpers>
            <admingridcategoryfilter>
                <class>SoftProdigy_AdminGridCategoryFilter_Helper</class>
            </admingridcategoryfilter>
        </helpers>
        <blocks>
            <admingridcategoryfilter>
                <class>SoftProdigy_AdminGridCategoryFilter_Block</class>
            </admingridcategoryfilter>
        </blocks>
    </global>
    <adminhtml>
        <events>
            <core_block_abstract_prepare_layout_before>
                <observers>
                    <admingridcategoryfilter>
                        <class>admingridcategoryfilter/observer</class>
                        <method>addCategoryFilterToProductGrid</method>
                    </admingridcategoryfilter>
                </observers>
            </core_block_abstract_prepare_layout_before>
        </events>
    </adminhtml>
</config>

Create a new file on app/code/local/SoftProdigy/AdminGridCategoryFilter/Helper/Data.php location and add following code:

<?php
class SoftProdigy_AdminGridCategoryFilter_Helper_Data extends Mage_Core_Helper_Abstract
{

}

Create a new file on app/code/local/SoftProdigy/AdminGridCategoryFilter/Model/Observer.php location and add following code:

<?php
class SoftProdigy_AdminGridCategoryFilter_Model_Observer
{

    public function addCategoryFilterToProductGrid(Varien_Event_Observer $observer)
    {   
        $block = $observer->getEvent()->getBlock();
        if( ($block instanceof Mage_Adminhtml_Block_Catalog_Product_Grid)  ) {
            $block->addColumnAfter('softprodigy_category_list', array(
                    'header'    => Mage::helper('admingridcategoryfilter')->__('Category'),
                    'index'     => 'softprodigy_category_list',
                    'sortable'  => false,
                    'width' => '250px',
                    'type'  => 'options',
                    'options'   => Mage::getSingleton('admingridcategoryfilter/system_config_source_category')->toOptionArray(),
                    'renderer'  => 'admingridcategoryfilter/catalog_product_grid_render_category',
                    'filter_condition_callback' => array($this, 'filterCallback'),
            ),'name');
        }
    }

    public function filterCallback($collection, $column)
    {
        $value = $column->getFilter()->getValue();
        $_category = Mage::getModel('catalog/category')->load($value);
        $collection->addCategoryFilter($_category);

        return $collection;
    }

}

Create a new file on app/code/local/SoftProdigy/AdminGridCategoryFilter/Model/System/Config/Source/Category.php location and add following code:

<?php
class SoftProdigy_AdminGridCategoryFilter_Model_System_Config_Source_Category
{
    public function toOptionArray($addEmpty = true)
    {
        $options = array();
        foreach ($this->load_tree() as $category) {
            $options[$category['value']] =  $category['label'];
        }

        return $options;
    }



    public function buildCategoriesMultiselectValues(Varien_Data_Tree_Node $node, $values, $level = 0)
    {
        $level++;

        $values[$node->getId()]['value'] =  $node->getId();
        $values[$node->getId()]['label'] = str_repeat("--", $level) . $node->getName();

        foreach ($node->getChildren() as $child)
        {
            $values = $this->buildCategoriesMultiselectValues($child, $values, $level);
        }

        return $values;
    }

    public function load_tree()
    {
        $store = Mage::app()->getFrontController()->getRequest()->getParam('store', 0);
        $parentId = $store ? Mage::app()->getStore($store)->getRootCategoryId() : 1;  // Current store root category

        $tree = Mage::getResourceSingleton('catalog/category_tree')->load();

        $root = $tree->getNodeById($parentId);

        if($root && $root->getId() == 1)
        {
            $root->setName(Mage::helper('catalog')->__('Root'));
        }

        $collection = Mage::getModel('catalog/category')->getCollection()
        ->setStoreId($store)
        ->addAttributeToSelect('name')
        ->addAttributeToSelect('is_active');

        $tree->addCollectionData($collection, true);

        return $this->buildCategoriesMultiselectValues($root, array());
    }
}

Create a new file on app/etc/modules/SoftProdigy_AdminGridCategoryFilter.xml location and add following code:

<?xml version="1.0"?>
<config>
    <modules>
        <SoftProdigy_AdminGridCategoryFilter>
            <active>true</active>
            <codePool>local</codePool>
            <depends>
                <Mage_Catalog />
                <Mage_Adminhtml />
            </depends>
        </SoftProdigy_AdminGridCategoryFilter>
    </modules>
</config>

Now clear cache from cache management and you can see category column in product grid.

There is already one flexible module in github for managing grid columns of any entities(orders, products, customers etc.):
https://github.com/magento-hackathon/GridControl