How should I use starter content utility to show some default menus?

Question

I recently started working on a WordPress theme and found this utility. I'm currently using WordPress 4.7.4. I've made following modifications to my code,

In FUNCTION.PHP;

function mytheme_setup(){
    register_nav_menus( array(
    'side'    => __( 'Side Menu', 'mytheme' ),
    'social' => __( 'Social Links Menu', 'mytheme' ),
    ) );

    $starter_content = array(
    // Set up nav menus for each of the two areas registered in the theme.
    'nav_menu'  =>  array(
        // Assign a menu to the "side" location.
        'side'  =>  array(
            'name'  =>  __( 'Side Menu', 'mytheme' ),
            'items' =>  array(
                'link_recent'   =>  array(
                    'title' =>  _x( 'Recent Articles', 'Theme starter content' ),
                    'url'   =>  site_url( '/#recent-articles' ),
                ),
                'link_about'    =>  array(
                    'title' =>  _x( 'About Us', 'Theme starter content' ),
                    'url'   =>  site_url( '/#about-us' ),
                ),
                'link_contact'  =>  array(
                    'title' =>  _x( 'Contact', 'Theme starter content' ),
                    'url'   =>  site_url( '/#contact-us' ),
                ),
            ),
        ),

        // Assign a menu to the "social" location.
        'social' => array(
            'name' => __( 'Social Links Menu', 'mytheme' ),
            'items' => array(
                'link_facebook',
                'link_twitter',
                'link_instagram',
                'link_youtube',
            ),
        ),
    ),
    );

    $starter_content = apply_filters( 'mytheme_starter_content', $starter_content );

    add_theme_support('starter-content', $starter_content);
}
add_action( 'after_setup_theme', 'mytheme_setup' );

And, in FRONT-PAGE.PHP,

    <?php if ( has_nav_menu( 'side' ) ) : ?>
        <div class="navigation-side">

            <nav id="site-navigation" class="main-navigation" role="navigation">
            <?php
             wp_nav_menu( array(
                 'theme_location'    =>  'side',
             ));
             ?>
            </nav>

        </div><!-- .navigation-side -->
    <?php endif; ?>

But still, I can't find any starter content menus on my theme.

Answer 1

I think you've a typo here:

'nav_menu'  =>  array(

Replace it with:

'nav_menus'  =>  array(

We can also check out how it's setup in the default Twenty Seventeen theme and look further how it's implemented within get_theme_starter_content():

// And nav menu items are grouped into nav menus.
case 'nav_menus' :
    foreach ( $config[ $type ] as $nav_menu_location => $nav_menu ) {

        // Ensure nav menus get a name.
        if ( empty( $nav_menu['name'] ) ) {
            $nav_menu['name'] = $nav_menu_location;
        }

        $content[ $type ][ $nav_menu_location ]['name'] = $nav_menu['name'];

        foreach ( $nav_menu['items'] as $id => $nav_menu_item ) {
            if ( is_array( $nav_menu_item ) ) {

                // Item extends core content.
                if ( ! empty( $core_content[ $type ][ $id ] ) ) {
                    $nav_menu_item = array_merge( $core_content[ $type ][ $id ], $nav_menu_item );
                }

                $content[ $type ][ $nav_menu_location ]['items'][] = $nav_menu_item;
            } elseif ( is_string( $nav_menu_item ) && ! empty( $core_content[ $type ] ) && ! empty( $core_content[ $type ][ $nav_menu_item ] ) ) {
                $content[ $type ][ $nav_menu_location ]['items'][] = $core_content[ $type ][ $nav_menu_item ];
            }
        }
    }
    break;