Having trouble with how to filter the post listing from WordPress back-end base on something else like user role?  Read this!

Sometime you might have custom role, let’s say co-editor, setup using members plugin in your WordPress.  And then you want to achieve  showing all posts only to the user who has administrator role but user with co-editor role sees only some of the posts.  You could use the below code to overcome this saturation.

function custom_post_where( $where ) {
     if( is_admin() && ( !current_user_can('administrator') ) && ( current_user_can('co_editor') ) ) {
         // get current user
         global $current_user;
         get_currentuserinfo();
         $user_id = $current_user->ID;

         // you can add your own query here, something like this
         $where .= " AND ID IN (SELECT ID FROM $wpdb->posts WHERE post_author = $user_id)";
     }
     return $where;
}

// plug to this filter
add_filter( 'posts_where', 'custom_post_where' );