You might want to display all categories in homepage or any CMS page. There are different ways to get the category listing. Here are some:-

Get all categories

The following code will fetch all categories (both active and inactive) that are present in your Magento Shop.

$categories = Mage::getModel('catalog/category')
					->getCollection()
					->addAttributeToSelect('*');

Get all active categories

The following code will fetch all active categories that are present in your Magento Shop. Thus filtering the inactive categories.

$categories = Mage::getModel('catalog/category')
					->getCollection()
					->addAttributeToSelect('*')
					->addIsActiveFilter();

Get active categories of any particular level

The following code will fetch all active categories of certain/specific level. Here, I have chosen level 1. Also sorting categories by name.

$categories = Mage::getModel('catalog/category')
					->getCollection()
					->addAttributeToSelect('*')
					->addIsActiveFilter()
					->addLevelFilter(1)
					->addOrderField('name');

Get store specific categories

The following code will fetch all active store specific categories. The following helper function does so:-

getStoreCategories($sorted=false, $asCollection=false, $toLoad=true)

$helper = Mage::helper('catalog/category');

// sorted by name, fetched as collection
$categoriesCollection = $helper->getStoreCategories('name', true, false);

// sorted by name, fetched as array
$categoriesArray = $helper->getStoreCategories('name', false, false);

Hope this helps. Thanks.

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From the admin panel, you can only add attributes to product. To add attributes to category, you need to write sql query in your phpmyadmin or a better way would be creating a new custom module and adding attributes to category from the mysql setup file of the module.

By mysql setup file, I mean the file inside the directory YourNamespace/YourModule/sql/yourmodule_setup/

Create a new module and write the following in your module’s mysql setup file.

$installer = $this;
$setup = new Mage_Eav_Model_Entity_Setup('core_setup');
$installer->startSetup();

$setup->addAttribute('catalog_category', 'my_attribute', array(
	'group'     	=> 'General',
	'input'         => 'text',
    'type'          => 'varchar',
    'label'         => 'My Attribute',
	'backend'       => '',
	'visible'       => 1,
	'required'		=> 0,
	'user_defined' => 1,
    'global'        => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_GLOBAL,
));

$installer->endSetup();

The above code will create a category with the code ‘my_attribute‘ and lable ‘My Attribute‘. You can view it under Admin Panel –> Catalog –> Manage Categories –> General Information

Hope this helps. Thanks.

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5. Magento 1.4: No products displayed in category listing

I have a fresh installation of Magento 1.4. I already have installed the sample data for Magento.

Now, when I go to the category listing page, no products are displayed. It says “There are no products matching the selection.“.

By category listing page, I mean the product listing page displayed when any category is clicked. Like, product listing for Furniture category, product listing for Living Room category, etc.

Solution:

- Go to System -> Index Management
- Select All Checkbox
- In Actions, select ‘Reindex Data‘
- Click Submit

Now, go to the category listing page. You will be able to see the products.

Hope this helps. Thanks.

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Category ids are stored for product in a comma separated way. So, to filter product collection by more than one category, you have to use:
addAttributeToFilter(‘category_ids’,array(‘finset’=>$categoryIds));

$categoryIds can be a single category id or comma separated category ids.

The following code filters product collection by two category ids (36 and 37).

 $_productCollection = Mage::getResourceModel('reports/product_collection')
    ->addAttributeToSelect('*')
    ->addAttributeToFilter('category_ids',array('finset'=>'36,37'));

finset does so… when we use finset, the mysql function find_in_set is used in the sql query by Magento.

mysql function find_in_set:

FIND_IN_SET() looks for the first occurrence of a string within another string containing comma-separated values.

SELECT FIND_IN_SET(‘b’,'a,b,c,d’); // result = 2

Cheers!

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$currentCategory = Mage::registry('current_category');

You can get the parent category from the following code:

/**
 * You want the parent category of a sub-category
 * Let the sub-category be $subCategory
 */

$parentCategory = Mage::getModel('catalog/category')->load($subCategory->getParentId());

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Like, I have a category named Furniture. The sub categories under Furniture are Living Room and Bedroom. Now, I want to show the sub categories under Funiture and the products associated with the sub categories (Living Room and Bedroom).

Furniture
- Living Room (4)
- Bedroom (2)

/**
 * get current category
 */
$currCat = Mage::registry('current_category');

/**
 * get sub categories of current category
 */
$collection = Mage::getModel('catalog/category')->getCategories($currCat->getEntityId());

/**
 * looping through sub categories
 * only showing active sub categories ($cat->getIsActive())
 */
foreach($collection as $cat) {
	if($cat->getIsActive()) {
		$category = Mage::getModel('catalog/category')->load($cat->getEntityId());

		/**
		 * getting product collection for a particular category
		 * applying status and visibility filter to the product collection
  		 * i.e. only fetching visible and enabled products
  		 */
		$prodCollection = Mage::getResourceModel('catalog/product_collection')->addCategoryFilter($category);
		Mage::getSingleton('catalog/product_status')->addVisibleFilterToCollection($prodCollection);
		Mage::getSingleton('catalog/product_visibility')->addVisibleInCatalogFilterToCollection($prodCollection);

		?>

		<a href="<?php echo $category->getUrl() ?>"><?php echo $category->getName() ?></a> (<?php echo $prodCollection->count() ?>)<br/>

		<?php
	}
}

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<?php
/**
 * get categories from a product
 */
$categoryIds = $product->getCategoryIds();
/**
 * looping through the array of category ids
 */
foreach($categoryIds as $categoryId) {
	$category = Mage::getModel('catalog/category')->load($categoryId);
	?>
		Category: <a href="<?php echo $category->getCategoryUrl() ?>"><?php echo $category->getName() ?></a><br/>
	<?php
}
?>

Related posts:

1. Magento: How to filter product collection using 2 or more category filters?
2. Magento 1.4: No products displayed in category listing
3. Magento: Get sub categories and product count
4. Magento: Get current and parent category
5. Magento: Adding category attributes