Question

Possible Duplicate:
Symfony2 Twig unlimited child depth

I want to loop though a list of objects within Twig. The list has some sort of a self-referenced many-to-one relationship and can look like this:

• Item 1
• Item 2
  • Item 2 1
  • Item 2 2
    • Item 2 2 1
• Item 3
  • Item 3 1
• Item 4

So the definition within the entity looks like:

/**
 * @ORM\OneToMany(targetEntity="Item", mappedBy="parent")
 */
private $children;

/**
 * @ORM\ManyToOne(targetEntity="Item", inversedBy="children")
 * @ORM\JoinColumn(name="parent_id", referencedColumnName="id")
 */
private $parent;

I know want to create a list like from within twig like:

<ul>
    <li>Item 1</li>
    <li>
        Item 2
        <ul>
            <li>Item 2 1</li>
            <li>
                Item 2 2
                <ul>
                    <li>Item 2 2 1</li>
                </ul>
            </li>
        </ul>
    </li>
    <li>
        Item 3
        <ul>
            <li>Item 3 1</li>
        </ul>
    </li>
    <li>Item 4</li>
</ul>

How can this be done?

Answer 1

There are several ways of doing this in Twig. A very easy one is using a macro that is called recursively. This macro can be placed within the same file as the actual output and is referenced through: {{ _self.macroname(parameters) }}

See comments for detailed explanation:

<!-- send two variables to the macro: the list of objects and the current level (default/root is null) -->
{% macro recursiveList(objects, parent) %}

    <!-- store, whether there's an element located within the current level -->
    {% set _hit = false %}

    <!-- loop through the items -->
    {% for _item in objects %}

        <!-- get the current parent id if applicable -->
        {% set _value = ( null != _item.parent and null != _item.parent.id ? _item.parent.id : null ) %}

        <!-- compare current level to current parent id -->
        {% if (parent == _value) %}

            <!-- if we have at least one element open the 'ul'-tag and store that we already had a hit -->
            {% if not _hit %}
                <ul class="tab">
                {% set _hit = true %}
            {% endif %}

            <!-- print out element -->
            <li>
                {{ _item.title }}

                <!-- call the macro with the new id as root/parent -->
                {{ _self.recursiveList(objects, _item.id) }}
            </li>
        {% endif %}

    {% endfor %}

    <!-- if there was at least one hit, close the 'ul'-tag properly -->
    {% if _hit %}
        </ul>
    {% endif %}

{% endmacro %}

The only thing, that is left to do, is to call the macro from within the template one time:

{{ _self.recursiveList(objects) }}

Hope, somebody finds this useful, too.