single post navigation order (NOT chronological)

Question

in my main loop i show only posts of the 'artworks' post type, orderby=rand.

when i view a single artwork and use the next / prev nav, it disregards the main query and goes by chronological order - as described in the codex: http://codex.wordpress.org/Template_Tags/next_post_link

how can i store and use the random order generated at first to alter the post navigation order? any ideas?

the order would be randomized upon the reload of the home page, but within each session each 'random order' should be consistent.

so, for example:

1- home page i see posts in a random order (4,7,1,8,6,3). i click on post 8.

2- on the single view of post 8, the 'next' post would be 6, and the previous would be 1. etc..

3- i should be able to go through back and forth and the order would be consistent.

4- if i click on the title of the website or reload it again (not just history>back, but an actual reload). then there should be a new random order.

Answer 1

after a lot of trial and error WP transients came to save me!!

here is the solution for anyone that might need this...

in the index.php (outside the main loop) i save the current random order in a transient:

$order_array = array();
while ( $the_query->have_posts() ) :
    $the_query->the_post();
        $order_array[] = get_the_ID() ;
endwhile;

set_transient('post_order', $order_array, 100);
// the expiration can be whatever you want

// Restore original Post Data
wp_reset_postdata();

now in the single.php where i add the next and prev navigation functionality:

            $next_post_index = $current_post_index+1;
            echo "<br> next post index : " . $next_post_index;
            $next_post_id = $array[$next_post_index];
            echo " id: " . $next_post_id;
            if($next_post_id != '') {echo "<br><a href=" . get_permalink( $next_post_id ) . ">next</a>";}

            $previous_post_index = $current_post_index-1;
            echo "<br> previous post index : " . $previous_post_index;
            $previous_post_id = $array[$previous_post_index];
            echo " id: " . $previous_post_id;
            if($previous_post_id != '') {echo "<br><a href=" . get_permalink( $previous_post_id ) . ">previous</a>";}

this has a bit of extra markup because i was echoing everything along the way to check if it was working. i am sure that it can be cleaned up, but it works! and it does not display next or prev if there is no other post before or after it (i.e. first post only shows 'next' link)

yay, it works :)