在Twig模板引擎中打印子类别

Question

我在数组中有下一个数据结构。

$a = [['id' => 1, 'parent_id' => 0], ['id' => 2, 'parent_id' => 0], ['id' => 3, 'parent_id' => 2], ['id' =>  4, 'parent_id' => 3]];

我有所有主要类别的水平菜单（'parent_id'= 0）。 下一个代码将打印所有主要类别。

{% for dept in common.departments %}
                            {% if dept.parent_id == 0 %}
                                <li><a href="/{{ dept.seo_title }}/{{ dept.id }}/dept" class="black">{{ dept.title }}</a><!-- for subdepartments --></li>
                            {% endif %}
                        {% endfor %}

如何以树格式打印所有子类别？

示例：

Dept 1  Dept4  
 Dept5   Dept2  
  Dept7  Dept3

更改：

<div class="clearfix">                      
                    {% macro displayChildren(departments, parent_id, deep) %}
                        {% for dept in departments %}
                            {% if dept.parent_id == parent_id %}
                                <li><a href="/{{ dept.seo_title }}/{{ dept.id }}/dept" class="black" style="margin-left: {{ deep * 10 }}px;">{{ dept.title }}</a></li>
                                {{ _self.displayChildren(departments, dept.id, deep + 1) }}
                            {% endif %}
                        {% endfor %}
                    {% endmacro %}

                    {% for dept in common.departments %}
                        {% if (dept.parent_id == 0) %}
                        <li><a href="/{{ dept.seo_title }}/{{ dept.id }}/dept" class="black">{{ dept.title }}</a><div class="dropdown-menu"><ol class="nav">{{ _self.displayChildren(common.departments, dept.id, 0) }}</ol></div></li>
                        {% endif %}
                    {% endfor %}
                </div>          

Answer 1

使用宏和递归应该有效：

{{ _self.displayChildren(departments, 0, 0, '') }}

{% macro displayChildren(departments, parent_id, deep, concat) %}
    {% for dept in departments %}
        {%- if dept.parent_id == parent_id %}
            {% set subconcat = (concat ? concat ~ '-':'') ~ 'dept' ~ dept.id %}
            {{ subconcat }}
            {{ _self.displayChildren(departments, dept.id, deep + 1, subconcat) }}
        {% endif -%}
    {% endfor %}
{% endmacro %}

显示：

<div style="margin-left: 0px;">dept1</div>
<div style="margin-left: 0px;">dept2</div>
<div style="margin-left: 20px;">dept2-dept3</div>
<div style="margin-left: 40px;">dept2-dept3-dept4</div>

或解释：