.How to filtrate Magento category collection by rank?

Sometimes you need to get a list of all categories with a particular level for a custom navigation menu. This can be done as follows:

$model=Mage::getModel('catalog/category');
$categories=$model->getCollection()->addLevelFilter(2)
->addAttributeToSelect('*')->addIsActiveFilter();

However, this is not always correct. I think I should explain why, right?

If I will enter request to a base I will get the following: SELECT `main_table`.* FROM `catalog_category_flat_store_1` AS `main_table` WHERE (main_table.level <= 2) AND (is_active = ’1′)

It is very visible that condition <= is in use, what doesn’t fit, because filtering categories of 3 rd level we will also get categories with 2 nd level.

Due to this we should do filtration in the following way:


$categories=$model->getCollection()->addAttributeToFilter('level',2)
->addAttributeToSelect('*')->addIsActiveFilter();

After this we can do whatever we want with the collection.

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