Question

I created this really simple function following the documentary of WordPress and as I understood it, this code should be working just fine

query_posts(array('orderby' => 'rand', 'post__not_in' => $_SESSION['watched'], 'showposts' => 1));

and the code for the session is no more advanced then this

if(!in_array($post->ID, $_SESSION['watched'])){
    array_push($_SESSION['watched'],$post->ID);
}

If you know of any other solution or how to fix this specific one
all answers are very much appreciated… If I missed something out just tell me and I’ll add that information.

Answer 1

This topic on wordpress.org seems relevant to your question – there are obviously some rather weird issues with post__not_in.

Try this:

function removeSeenPosts ($where) {
    global $wpdb;
    if (count($_SESSION['watched']) > 0) {
        $where .= ' AND ' . $wpdb->posts . '.ID NOT IN(' . implode (',', $_SESSION['watched']) . ') ';
    }
    return $where;
}

add_filter('posts_where', 'removeSeenPosts');
query_posts(array('orderby' => 'rand', 'showposts' => 1));
remove_filter('posts_where', 'removeSeenPosts');

If that doesn’t help (which I actually suspect), the problem is clearly related to the post ids’ storage in the session.

Two things come to mind:

• Can $_SESSION be populated after anything but headers has been sent? I don’t remember …
• Storing the posts in a proper cookie seems like a viable alternative and would, as an added bonus, make the storage persistent across sessions.

Untested implementation as a plugin:

function setViewedPostCookies() {
    if (is_single())
    {
        global $wp_query;
        if (!isset($_COOKIE['watched']))
        {
            $excluded_posts = array();
        }
        else
        {
            $excluded_posts = implode(',', $_COOKIE['watched']);
        }
        $excluded_posts[] = $wp_query->post->ID;
        $excluded_posts = array_unique($excluded_posts);
        setcookie('watched', explode(',', $excluded_posts), time() + 3600000, '/');
    }
}

add_action( 'get_header', 'setViewedPostCookies' );