Recursive parsing of hierarchical Twig layout with parents, children, grandchildren - symfony

Question

In my SF2 project I have an entity (Category) which I am representing in a hierarchical format with a parent at the top, followed by children, grandchildren etc.
The Category entity has a getChildren method, which works and returns Category entity objects.
I'm trying to work out a way to make this layout more dynamic, rather than having to explicitly set children and grandchildren variables within the template.
Is there a better way to do this?
<ul class="sortable">
{% for cat in cats %}
{% set children = cat.getChildren %}
<li id="menuItem_{{ cat.id }}">
<div data-id="{{ cat.id }}">
<span>{{ cat.name }}</span>
</div>
{% for child in children %}
{% set grandchildren = child.getChildren %}
<ul>
<li id="menuItem_{{ child.id }}">
<div data-id="{{ child.id }}">
{{ child.name }}
</div>
{% for grandchild in grandchildren %}
<ul>
<li id="menuItem_{{ grandchild.id }}">
<div data-id="{{ grandchild.id }}">
{{ grandchild.name }}
</div>
</li>
</ul>
{% endfor %}
</li>
</ul>
{% endfor %}
</li>
{% endfor %}
</ul>

Answer 1

so what you are trying to achieve is recursive parsing of a tree in twig right?
If so, have a look at macros
.
{% import _self as macros %}
{% macro showChild(object) %}
{% import _self as macros %}
<ul>
{% for child in object.children %}
{{ macros.showChild(child) }}
{% endfor %}
<li id="menuItem_{{ object.id }}">
<div data-id="{{ object.id }}">
{{ object.name }}
</div>
</li>
</ul>
{% endmacro %}
<ul class="sortable">
{% for cat in cats %}
{{ macros.showChild(cat) }}
{% endfor %}
</ul>
that's all :)
let me know if you need help
EDIT 1:
If you want to use the macro in another file, remove the "import _self" line and just import it with an alias in another file:
index.html.twig:
{% import 'macro_file_name.html.twig' as macros %}
then you can use the same notation to call it