Get only the first level of child categories

Question

I would like to list only the first level child categories of the current category.

This is what is have right now:

$_category = Mage::registry('current_category')->getId();    
$_categories = $_category
                ->getCollection()
                ->addAttributeToSelect(array('name', 'image', 'description'))
                ->addIdFilter($_category->getChildren());

foreach ($_categories as $_category):
   echo $_category->getName();
endforeach;

The shop is using flat categories, and i have no idea how to show only the first level of child categories.

Been searching a lot but every script i use still show all the sub-sub categories instead only the sub categories.

EDIT:

Just to be clear

When the current page is:

Category (current page)

-- sub A <-- show this sub category
--- sub A sub
---- sub A sub sub

-- sub B <-- show this sub category
--- sub B sub
---- sub B sub sub

Category 

-- sub A (current page) 
--- sub A sub <-- show this sub category
---- sub A sub sub

-- sub B
--- sub B sub
---- sub B sub sub

Answer 1

use below code to get first level category

  $categories = Mage::getModel('catalog/category')
                ->getCollection()
                ->addAttributeToSelect('*')
                ->addIsActiveFilter()
                ->addAttributeToFilter('include_in_menu','1')
                ->addAttributeToFilter('level','1');


    foreach($categories as $item)
    {
        echo $item->getName();
    }

Answer 2

For getting all immediate child categories try this

For getting get immediate active categories:

$_category = Mage::registry('current_category');    
$_categories = $_category->getChildrenCategories()
                ->addAttributeToSelect(array('name', 'image', 'description'))
                ;

foreach ($_categories as $_category):
   echo $_category->getName().'<br/>';
endforeach;

With Including inactive Children categories:

$_category = Mage::registry('current_category');    
$_categories = $_category->getChildrenCategoriesWithInactive($_category)
                ->addAttributeToSelect(array('name', 'image', 'description'))
                ;

foreach ($_categories as $_category):
   echo $_category->getName().'<br/>';
endforeach;

Answer 3

You can use the following method to get the first level child categories of the given category. $_categories = $category->getResource()->getChildren($category,false); Where false in the argument is for recursive, so if you want the recursive categories, you can replace the false with true.

Answer 4

You can use this way

$cat_id = Mage::registry('current_category')->getId();
$sub_categories = Mage::getModel('catalog/category')->getCategories($cat_id);

or you can also filter the category collection by parent id

$cat_id = Mage::registry('current_category')->getId();
$sub_categories = Mage::getModel('catalog/category')
    ->getCollection()
    ->addAttributeToFilter("parent_id",$cat_id);

For me i prefer first method hope this will help you