Simple nested navigation

Question

I'm new to Craft CMS. I have the following single level navigation code:

<ul>
  <li>
    <a href="/products" class="app-nav__primary">Products</a>
    <ul class="app-nav__secondary">
      {% for entry in craft.entries.section('products') %}
      <li><a href="{{ entry.url }}">{{ entry.title }}</a>
      </li>
      {% endfor %}
    </ul>
  </li>
</ul>

How would i adjust this to show a second level navigation in within the parent li? I'm looking for something like this:

<ul>
  <li>
    <a href="/products" class="app-nav__primary">Products</a>
    <ul class="app-nav__secondary">
      {% for entry in craft.entries.section('products') %}
      <li><a href="{{ entry.url }}">{{ entry.title }}</a>
        if (child) { '
          <li><a href="child.link">child.title</a>
        }
        </li>
        {% endfor %}
    </ul>
    </li>
</ul>

Answer 1

You could use the children tag:

{% set entries = craft.entries.section('products') %}
<ul>
    <li>
        <a href="/products" class="app-nav__primary">Products</a>
        <ul class="app-nav__secondary">
            {% nav entry in entries %}
                <li>
                    <a href="{{ entry.url }}">{{ entry.title }}</a>
                    {% ifchildren %}
                        <ul>
                            {% children %}
                        </ul>
                    {% endifchildren %}
                </li>
            {% endnav %}
        </ul>
    </li>
</ul>