Wordpress - 从自定义字段向移动菜单显示字幕

Question

I am trying to show subtitle to my mobile menu items.

For that I have created a custom field to show as page_subheading for each page.

I can get the value of this custom field using pageId. But I am not able to append this sub heading to the menu.

I have tried the the below code,

wp_nav_menu( array(
        'theme_location' => 'mobile_menu_alt',
        'menu_class'     => 'dropdown-menu',
        'fallback_cb'    => false,
        'link_after'     => '</span><div class="subheading">'.$subheading.'</a></div>',
    ) );

Here I am calling my menu and adding the subheading after the menu link. But I am not able to give it dynamically.Is there any way to give value to $subheading dynamically.

Answer 1

Try adding this to your functions.php

class Walker_Nav_Menu_subheading extends Walker {
/**
 * What the class handles.
 *
 * @see Walker::$tree_type
 * @since 3.0.0
 * @var string
 */
public $tree_type = array( 'post_type', 'taxonomy', 'custom' );

/**
 * Database fields to use.
 *
 * @see Walker::$db_fields
 * @since 3.0.0
 * @todo Decouple this.
 * @var array
 */
public $db_fields = array( 'parent' => 'menu_item_parent', 'id' => 'db_id' );

/**
 * Starts the list before the elements are added.
 *
 * @see Walker::start_lvl()
 *
 * @since 3.0.0
 *
 * @param string $output Passed by reference. Used to append additional content.
 * @param int    $depth  Depth of menu item. Used for padding.
 * @param array  $args   An array of arguments. @see wp_nav_menu()
 */
public function start_lvl( &$output, $depth = 0, $args = array() ) {
    $indent = str_repeat("\t", $depth);
    $output .= "
$indent<ul class=\"sub-menu\">
";
}

/**
 * Ends the list of after the elements are added.
 *
 * @see Walker::end_lvl()
 *
 * @since 3.0.0
 *
 * @param string $output Passed by reference. Used to append additional content.
 * @param int    $depth  Depth of menu item. Used for padding.
 * @param array  $args   An array of arguments. @see wp_nav_menu()
 */
public function end_lvl( &$output, $depth = 0, $args = array() ) {
    $indent = str_repeat("\t", $depth);
    $output .= "$indent</ul>
";
}

/**
 * Start the element output.
 *
 * @see Walker::start_el()
 *
 * @since 3.0.0
 * @since 4.4.0 'nav_menu_item_args' filter was added.
 *
 * @param string $output Passed by reference. Used to append additional content.
 * @param object $item   Menu item data object.
 * @param int    $depth  Depth of menu item. Used for padding.
 * @param array  $args   An array of arguments. @see wp_nav_menu()
 * @param int    $id     Current item ID.
 */
public function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
    $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';

    $classes = empty( $item->classes ) ? array() : (array) $item->classes;
    $classes[] = 'menu-item-' . $item->ID;

    /**
     * Filter the arguments for a single nav menu item.
     *
     * @since 4.4.0
     *
     * @param array  $args  An array of arguments.
     * @param object $item  Menu item data object.
     * @param int    $depth Depth of menu item. Used for padding.
     */
    $args = apply_filters( 'nav_menu_item_args', $args, $item, $depth );

    /**
     * Filter the CSS class(es) applied to a menu item's list item element.
     *
     * @since 3.0.0
     * @since 4.1.0 The `$depth` parameter was added.
     *
     * @param array  $classes The CSS classes that are applied to the menu item's `<li>` element.
     * @param object $item    The current menu item.
     * @param array  $args    An array of {@see wp_nav_menu()} arguments.
     * @param int    $depth   Depth of menu item. Used for padding.
     */
    $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args, $depth ) );
    $class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

    /**
     * Filter the ID applied to a menu item's list item element.
     *
     * @since 3.0.1
     * @since 4.1.0 The `$depth` parameter was added.
     *
     * @param string $menu_id The ID that is applied to the menu item's `<li>` element.
     * @param object $item    The current menu item.
     * @param array  $args    An array of {@see wp_nav_menu()} arguments.
     * @param int    $depth   Depth of menu item. Used for padding.
     */
    $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        : '';

    /**
     * Filter the HTML attributes applied to a menu item's anchor element.
     *
     * @since 3.6.0
     * @since 4.1.0 The `$depth` parameter was added.
     *
     * @param array $atts {
     *     The HTML attributes applied to the menu item's `<a>` element, empty strings are ignored.
     *
     *     @type string $title  Title attribute.
     *     @type string $target Target attribute.
     *     @type string $rel    The rel attribute.
     *     @type string $href   The href attribute.
     * }
     * @param object $item  The current menu item.
     * @param array  $args  An array of {@see wp_nav_menu()} arguments.
     * @param int    $depth Depth of menu item. Used for padding.
     */
    $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 . '"';
        }
    }

    /** This filter is documented in wp-includes/post-template.php */
    $title = apply_filters( 'the_title', $item->title, $item->ID );

    /**
     * Filter a menu item's title.
     *
     * @since 4.4.0
     *
     * @param string $title The menu item's title.
     * @param object $item  The current menu item.
     * @param array  $args  An array of {@see wp_nav_menu()} arguments.
     * @param int    $depth Depth of menu item. Used for padding.
     */
    $title = apply_filters( 'nav_menu_item_title', $title, $item, $args, $depth );

            $subheading = get_post_meta($item->ID, 'subheading', true);

    $item_output = $args->before;
    $item_output .= '<a'. $attributes .'>';
    $item_output .= $args->link_before . $title . "<span 'subheading'>" . $subheading . "</span>";
    $item_output .= '</a>';
    $item_output .= $args->after;

    /**
     * Filter a menu item's starting output.
     *
     * The menu item's starting output only includes `$args->before`, the opening `<a>`,
     * the menu item's title, the closing `</a>`, and `$args->after`. Currently, there is
     * no filter for modifying the opening and closing `<li>` for a menu item.
     *
     * @since 3.0.0
     *
     * @param string $item_output The menu item's starting HTML output.
     * @param object $item        Menu item data object.
     * @param int    $depth       Depth of menu item. Used for padding.
     * @param array  $args        An array of {@see wp_nav_menu()} arguments.
     */
    $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
}

/**
 * Ends the element output, if needed.
 *
 * @see Walker::end_el()
 *
 * @since 3.0.0
 *
 * @param string $output Passed by reference. Used to append additional content.
 * @param object $item   Page data object. Not used.
 * @param int    $depth  Depth of page. Not Used.
 * @param array  $args   An array of arguments. @see wp_nav_menu()
 */
public function end_el( &$output, $item, $depth = 0, $args = array() ) {
    $output .= "</li>
";
}

} // Walker_Nav_Menu_subheading

and this into your theme file, such as heading.php

wp_nav_menu( array(
    'theme_location' => 'mobile_menu_alt',
    'menu_class'     => 'dropdown-menu',
    'fallback_cb'    => false,
    'walker'         => new Walker_Nav_Menu_subheading()
) );

It relies on you using the post_meta name of 'subheading'....

All I did was make a copy of the standard wordPress one and changed how the after bit works.

these lines

$subheading = get_post_meta($item->ID, 'subheading', true);

$item_output = $args->before;
$item_output .= '<a'. $attributes .'>';
$item_output .= $args->link_before . $title . "<span 'subheading'>" . $subheading . "</span>";