magento: show all products below a parent node - magento

Question

On a magento site, we've got one menu where we would like to always show all the products below a parent node, let's say we have got
Root
- category 1
- category 2
---- subcategory 2-1
---- subcategory 2-2
When clicking on category 2, we would like to see all products assigned to category2, 2-1 and 2-2. When clicking on Root, it should show ALL the products of the store. However, when selecting category1 from within the other sections of the store, we would like to have a default behaviour.
Normally, we would just assign a product to various categories - but as we only want this behaviour on one single section of the site, I'm not sure how to handle this.
Any ideas?
Thanks in advance.

Answer 1

You can use the "Anchor" attribute of a category to achieve this, this setting controls how Magento 'rolls up' products from categories below the one it's applied to and in doing so also sets a scope for layered navigation controls (if you are using them).
To work as described you'll need to tick/untick the "Is Anchor" box on each child category under the parent appropriately.
Go to Catalog > Manage Catagories > Select a category > Display Settings > Is Anchor? (tick)
To get the behaviour you're after you'll need to set the "Is Anchor" box as follows:
Root - tick
- category 1 - untick
- category 2 - tick
-- foreach child of category 2 - tick
Then reindex anything category related.

Answer 2

Display top level and all sub categories :
$collection= Mage::helper('catalog/category');
$categories = $collection->getStoreCategories();
$currentCategory = Mage::registry('current_category');
<ul>
<?php foreach($categories as $category): ?>
<li><a href="<?php echo $collection->getCategoryUrl($category) ?>">
<?php echo $category->getName() ?>
</a>
<?php $category = Mage::getModel('catalog/category')->load($category->getId()) ?>
<?php $subCategory = $category->getChildrenCategories() ?>
<?php if(count($subCategory > 0)): ?>
<ul>
<?php foreach($subCategory as $_subCategory):) ?>
<li>
<a href="<?php echo $collection->getCategoryUrl($_subCategory) ?>">
<?php echo $_subCategory->getName() ?>
</a>
</li>
<?php endforeach; ?>
</ul>
<?php endif; ?>
</li>
<?php endforeach; ?>
</ul>