The construction of the nav menu links is controlled by the start_el()
method of the Walker_Nav_Menu
class. It’s possible to change its behaviour by extending Walker_Nav_Menu
to a new class, and replacing the start_el()
method with your own. You can then use your new walker by setting the walker
argument of wp_nav_menu()
.
So the first step would be to create a new class (let’s call it Box_Link_Walker
), and the copy the entirety of start_el()
method of the Walker_Nav_Menu
into it (I have removed all the inline documentation of the original method to save space in this answer):
class Box_Link_Walker extends Walker_Nav_Menu {
public function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
$t="";
$n = '';
} else {
$t = "\t";
$n = "\n";
}
$indent = ( $depth ) ? str_repeat( $t, $depth ) : '';
$classes = empty( $item->classes ) ? array() : (array) $item->classes;
$classes[] = 'menu-item-' . $item->ID;
$args = apply_filters( 'nav_menu_item_args', $args, $item, $depth );
$class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args, $depth ) );
$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';
$id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args, $depth );
$id = $id ? ' id="' . esc_attr( $id ) . '"' : '';
$output .= $indent . '<li' . $id . $class_names .'>';
$atts = array();
$atts['title'] = ! empty( $item->attr_title ) ? $item->attr_title : '';
$atts['target'] = ! empty( $item->target ) ? $item->target : '';
$atts['rel'] = ! empty( $item->xfn ) ? $item->xfn : '';
$atts['href'] = ! empty( $item->url ) ? $item->url : '';
$atts = apply_filters( 'nav_menu_link_attributes', $atts, $item, $args, $depth );
$attributes="";
foreach ( $atts as $attr => $value ) {
if ( ! empty( $value ) ) {
$value = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
$attributes .= ' ' . $attr . '="' . $value . '"';
}
}
$title = apply_filters( 'the_title', $item->title, $item->ID );
$title = apply_filters( 'nav_menu_item_title', $title, $item, $args, $depth );
$item_output = $args->before;
$item_output .= '<a'. $attributes .'>';
$item_output .= $args->link_before . $title . $args->link_after;
$item_output .= '</a>';
$item_output .= $args->after;
$output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
}
}
The only bits we need to worry about are this section:
$atts['title'] = ! empty( $item->attr_title ) ? $item->attr_title : '';
$atts['target'] = ! empty( $item->target ) ? $item->target : '';
$atts['rel'] = ! empty( $item->xfn ) ? $item->xfn : '';
$atts['href'] = ! empty( $item->url ) ? $item->url : '';
Where you just need to add a line that will add the box-link
class to the anchor element:
$atts['class'] = 'box-link';
And this section:
$item_output = $args->before;
$item_output .= '<a'. $attributes .'>';
$item_output .= $args->link_before . $title . $args->link_after;
$item_output .= '</a>';
$item_output .= $args->after;
Which just needs to be rearranged to move the title outside of the anchor element:
$item_output = $args->before;
$item_output .= '<a'. $attributes .'>';
$item_output .= '</a>';
$item_output .= $args->link_before . $title . $args->link_after;
$item_output .= $args->after;
Now you can apply this new markup to your menu by setting the walker
argument of wp_nav_menu()
:
wp_nav_menu( array(
'theme_location' => 'primary-menu',
'menu_id' => 'primary-menu',
'walker' => new Box_Link_Walker(),
) );
That out of the way, I feel I should point out that structuring your links this way is bad for accessibility, as to screen readers – and search engine robots, for that matter – the link won’t appear to have a label. I would advise against implementing this. Whatever CSS effect you’re trying to apply is almost certainly possible without breaking the links’ accessibility.