How to get a post from another site in the network
This tutorial is part of our MultilingualPress 2 documentation. In case you are using the newer version 3, please switch to MultilingualPress 3.
Let’s say we have a site id and a post id. The source doesn’t matter, it could be a database, user input, whatever. Now we want to get a WP_Post object from that site.
A first idea might look like this:
switch_to_blog( $site_id );
$post = get_post( $post_id );
restore_current_blog();
But this is not necessary, there is already a function in WordPress for that:
function get_blog_post( $blog_id, $post_id ) {
switch_to_blog( $blog_id );
$post = get_post( $post_id );
restore_current_blog();
return $post;
}
Nice, but there is an important, subtle bug in that function: it is using get_post( $post_id ) without a check on the post id. If $post_id is 0, NULL or “”, get_post() will use an existing global post object or id. But the current global post is from the source site, not from the target site! The id on site 1 references a completely different post than on site 2.
WordPress doesn’t care. So we have to do that check:
$post = NULL;
if ( ! empty ( $post_id ) )
$post = get_blog_post( $site_id, $post_id );