How to remove private posts from next / previous posts in WordPress? - wordpress

Question

I have implemented Vue.js single page application in a WordPress theme (wue-theme.app) and want to navigate through the blog posts by next / previous links from within the single-post template. But I struggle to remove private posts from the links - there are no WP_Query options available. So how can I navigate through the posts with the status "publish" only?

Answer 1

Unfortunately I couldn't find any documented "official" ways to do this. So I "hacked" a bit the default SQL query which you can fortunately apply a filter on, and have removed the "private" post_status from the query. This is the full custom code for the "post" post type you have to place in your functions.php:
add_filter( 'rest_prepare_post', 'technomad_post_api_hook', 10, 3 );
function technomad_post_api_hook( $response ) {
if ( isset( $_REQUEST["slug"] ) ) {
add_filter( "get_next_post_where", function($query, $in_same_cat, $excluded_categories, $taxonomy, $post){
$query = str_replace("OR p.post_status = 'private'", "", $query);
return $query;
}, 100, 5 );
add_filter( "get_previous_post_where", function($query, $in_same_cat, $excluded_categories, $taxonomy, $post){
$query = str_replace("OR p.post_status = 'private'", "", $query);
return $query;
}, 100, 5 );
$next = get_adjacent_post( false, '', false );
$previous = get_adjacent_post( false, '', true );
if ( is_a( $next, 'WP_Post' ) ) {
$response->data['next'] = array(
"id" => $next->ID,
"slug" => $next->post_name,
"title" => $next->post_title,
);
} else {
$response->data['next'] = null;
}
if ( is_a( $previous, 'WP_Post' ) ) {
$response->data['previous'] = array(
"id" => $previous->ID,
"slug" => $previous->post_name,
"title" => $previous->post_title,
);
} else {
$response->data['previous'] = null;
}
}
}
You can also just return your own custom query instead of str_replace():
return $wpdb->prepare( "WHERE p.post_title > %s AND p.post_type = %s AND ( p.post_status = 'publish' )", $post->post_title, $post->post_type );