WP Multisite: load content from site X on site Y

I’m running a WP multisite-network on my professional website (http://mydomain.com). I’d like to play around with jQuery Mobile and deliver a different website and web experience to mobile users, so I created another site in this network on http://m.mydomain.com.

On the main (desktop) WP site, I created a “project” content type to sort my professional projects. On the mobile site I’ll create, I’d like to be able to load these projects (from the desktop-WP db) instead of having to recreate all the projects to the mobile-WP site.

I already worked on something similar: I had to access WP content through a subdomain of the main WP site, using the ‘require wp-load.php’ technique, but I’m wondering if there is a built-in function in WP to do this in a cleaner way, as both sites are on the same network.

You can just use the function switch_to_blog before running the WP_Query on your post_type “projects”.

Switch the current blog to a different blog. switch_to_blog(), is
useful if you need to pull posts or other information from other
blogs.

Sounds like this is what you want. So lets say you have your content on the main_site. Run this on the mobilesite:

// Get current blog_id
global $blog_id;

// Run this code if on mobilesite
// Change from blog_id 2 if another id
if( $blog_id == 2 ) {

    // Switch to the main_site
    switch_to_blog(1);

        // Get from projects and all of the posts
        $args = array(
            'post_type'  => 'projects',
            'posts_per_page' => -1
        );

        // The Query
        $the_query = new WP_Query( $args );

        // The Loop
        while ( $the_query->have_posts() ) :
            $the_query->the_post();
            echo '<li>' . get_the_title() . '</li>';
        endwhile;

        // Restore original Query & Post Data
        wp_reset_query();

    // Switch back to mobilesite
    restore_current_blog();
}