Wordpress add a class to menu link - php

Question

I need your help. I need to add a specific class on the link that wordpress generates in the menu.
What should I edit?
The HTML output in my case is:
<nav class="nav" role="navigation">
<ul>
<li id="menu-item-8" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-8">Sample Page</li>
<li id="menu-item-9" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-9">Prova sample</li>
</ul></nav
the code in the header file that generate the menu is:
<!-- nav -->
<nav class="nav" role="navigation">
<?php html5blank_nav(); ?>
</nav>
<!-- /nav -->

Answer 1

You can do it through admin panel also
In Appearance > Menus, click the Screen Options tab
Under Show advanced menu properties, check CSS Classes
Now expand any menu item to reveal the CSS Classes (optional) text
input.
Enter your class name and save your menu to apply the class to the
menu item
http://sevenspark.com/how-to/how-to-add-a-custom-class-to-a-wordpress-menu-item

Answer 2

Adds a class <a class=>
https://codex.wordpress.org/Plugin_API/Filter_Reference/nav_menu_link_attributes
function add_specific_menu_location_atts( $atts, $item, $args ) {
// check if the item is in the primary menu
if( $args->menu == 'primary' ) {
// add the desired attributes:
$atts['class'] = 'menu-link-class';
}
return $atts;
}
add_filter( 'nav_menu_link_attributes', 'add_specific_menu_location_atts', 10, 3 );

Answer 3

After creating some WordPress sites based on the Bootstrap framework, i've come up with a solution of easily manipulating the WordPress navigation output by initializing the classes you want. This will make sure your enduser will not be needed to add all the custom classes when the client add's a new menu item.
Maybe it could help someone;
https://github.com/nickkuijpers/WordPress-Extended-Bootstrap-Nav-Walker

Answer 4

Try edit html5blank_nav() function, in functions.php file
// HTML5 Blank navigation
function html5blank_nav()
{
wp_nav_menu(
array(
'theme_location' => 'header-menu',
'menu' => '',
'container' => 'div',
'container_class' => 'menu-{menu slug}-container',
'container_id' => '',
'menu_class' => 'menu',
'menu_id' => '',
'echo' => true,
'fallback_cb' => 'wp_page_menu',
'before' => '',
'after' => '',
'link_before' => '',
'link_after' => '',
'items_wrap' => '<ul>%3$s</ul>',
'depth' => 0,
'walker' => ''
)
);
}