I have a plugin that lists only items from ONE LEVEL of subcategories. Here is PHP code:

do{
$db->setQuery("SELECT id FROM #__k2_categories WHERE parent IN(".implode(",",$level).")");
$level = (array)$db->loadResultArray();
//if(is_array($level) && count($level) > 0){
$catid = array_merge((array)$catid,(array)$level);
//}
//else break;
}while($db->getNumRows() > 0);

And here is examle of what items do it lists, i have this categories:

Category1
--Subcategory 1 (Item1, Item2)
----Subcategory 1a (Item1a)
----Subcategory 1b (item1b)
--Subcategory2 (Item3)

And when I open Category1, it onli lists Item1, Item2 and Item3. Can someone please help me to get Item1a and Item1b...

Sorry for bad english, and thank you!

Hello, Boris.

I am not complitely undertood your example, but you can use a getCategoryTree function from itemlist model for this purpose.