Get category children

Question

I would like to select just the children of any given main category (eg. Accessories, Stomps in the picture), regardless of segments in my URL.

I've been trying to understand why the code below won't work.

This just won't work. Why?

{% set categoryGroup = craft.categories.group('productTypes').descendantOf('accessories') %}
<ul>
    {% for category in categoryGroup %}
        <li class="category">{{ category.title }}</li>    
    {% endfor %}
</ul>

Answer 1

Because the descendantOf function expects a parameter of type ElementInterface or an integer

 /**
 * Sets the [[descendantOf]] property.
 *
 * @param int|ElementInterface|null $value The property value
 *
 * @return static self reference
 */
public function descendantOf($value);

You'll have to insert the ID of your accessories element or the element itself

{% accessories = craft.categories.title('accessories').first() %}
{% set categoryGroup = craft.categories.group('productTypes').descendantOf(accessories) %}