Custom classes for menu links

Question

How can I add custom classes for links into main menu in Drupal 8. This is template for my main menu called menu--main.html.twig

{% import _self as menus %}
{{ menus.menu_links(items, attributes, 0) }}

{% macro menu_links(items, attributes, menu_level) %}
  {% import _self as menus %}
  {% if items %}
    {% if menu_level == 0 %}
        <ul{{ attributes.addClass('main-nav') }}>

        {% for item in items %}
        <li{{ item.attributes.addClass('main-nav__item') }}>
            {{ link(item.title, item.url) }}
            {% if item.below %}
                {{ menus.menu_links(item.below, attributes, menu_level + 1) }}
            {% endif %}
        </li>
        {% endfor %}
    {% else %}
        <ul class="main-nav__sub js-nav-submenu ">

        {% for item in items %}
        <li{{ item.attributes.addClass('main-nav__sub-item') }}>
            {{ link(item.title, item.url) }}
            {% if item.below %}
                {{ menus.menu_links(item.below, attributes, menu_level + 1) }}
            {% endif %}
        </li>
        {% endfor %}
    {% endif %}
    </ul>
  {% endif %}
{% endmacro %}

And I need to achieve this result:

<ul class="main-nav">
  <li class="main-nav__item"><a class="main-nav__link main-nav__link--active" href="index.html">Úvod</a></li>
  <li class="main-nav__item"><a class="main-nav__link js-nav-submenu-toggler" href="#">O škole</a>
    <ul class="main-nav__sub js-nav-submenu">
      <li class="main-nav__sub-item"><a class="main-nav__sub-link" href="#">Aktuality</a></li>
      <li class="main-nav__sub-item"><a class="main-nav__sub-link " href="pedagogovia.html">Pedagógovia</a></li>
      <li class="main-nav__sub-item"><a class="main-nav__sub-link" href="#">Dokumenty</a></li>
      <li class="main-nav__sub-item"><a class="main-nav__sub-link " href="historia.html">História</a></li>
    </ul>
  </li>
  <li class="main-nav__item"><a class="main-nav__link" href="#">Informácie o štúdiu</a></li>
  <li class="main-nav__item"><a class="main-nav__link" href="#">Fotogaléria</a></li>
  <li class="main-nav__item"><a class="main-nav__link " href="kontakt.html">Kontakt</a></li>
</ul>

My problem is that I don't know how to set custom class for <a href=""> tags. Is there any way how can do it using link() function. In Drupal 7 is l() function but attributes aren't similar. l() has also third attribute with possibility to add options. Is it true, that link($title, $url) accepts only 2 parameters? Because I can't find the way how to send options for link($title, $url). I don't insit on link() function, so if there is some better way please let me know. I'm open to new ideas :)

Thanks

Answer 1

Just incase someone stumbles upon this, Martin's solve above breaks URL fragments as it overrides the URL options completely. The better approach is here:

{{ link(item.title, item.url.setOption('attributes', {'class' : 'main-nav__link'})) }}

Answer 2

Just replace

{{ link(item.title, item.url) }}

by

{{ link(item.title, item.url, { 'class':['main-nav__link']}) }}

Answer 3

I finally solved it using next syntax in Twig template

{{ link(item.title, item.url.setOptions({'set_active_class' : TRUE, 'attributes' : {'class' : 'main-nav__link'}})) }}

Answer 4

file name /var/www/html/drupal/themes/theme_name/templates/navigation/menu.html.twig

we are checking menu name in if condition {% if menu_name ==’account’ %}

below is the whole code you may copy and replace it

  {#
  /**
   * @file
   * Theme override to display a menu.
   *
   * Available variables:
   * - menu_name: The machine name of the menu.
   * - items: A nested list of menu items. Each menu item contains:
   *   - attributes: HTML attributes for the menu item.
   *   - below: The menu item child items.
   *   - title: The menu link title.
   *   - url: The menu link url, instance of \Drupal\Core\Url
   *   - localized_options: Menu link localized options.
   *   - is_expanded: TRUE if the link has visible children within the current
   *     menu tree.
   *   - is_collapsed: TRUE if the link has children within the current menu tree
   *     that are not currently visible.
   *   - in_active_trail: TRUE if the link is in the active trail.
   */
  #}
  {% import _self as menus %}

  {#
    We call a macro which calls itself to render the full tree.
    @see http://twig.sensiolabs.org/doc/tags/macro.html
  #}
  {{ menus.menu_links(items, attributes, 0,menu_name) }}


  {% macro menu_links(items, attributes, menu_level,menu_name) %}
    {% import _self as menus %}
    {% if items %}

      {% if menu_level == 0 %}
            {% if menu_name =='account' %}
                <ul{{ attributes.addClass('') }}>
            {% endif %}

            {% if menu_name =='main' %}
                <ul{{ attributes.addClass('menu nav navbar-nav') }}>
            {% endif %}

      {% else %}
              <ul{{ attributes.addClass('menu nav navbar-nav') }}>
      {% endif %}
      {% for item in items %}
        {%
          set classes = [
            'menu-item',
            item.is_expanded ? 'menu-item--expanded',
            item.is_collapsed ? 'menu-item--collapsed',
            item.in_active_trail ? 'menu-item--active-trail',
          ]
        %}
        <li{{ item.attributes.addClass(classes) }}>
          {{ link(item.title, item.url) }}
          {% if item.below %}
            {{ menus.menu_links(item.below, attributes, menu_level + 1) }}
          {% endif %}
        </li>
      {% endfor %}
      </ul>
    {% endif %}
  {% endmacro %}