How do I create a random post that will last for a day

4 comments

1. Here is some code doing what you’ve asked and using the ideas others have highlighted:

   <?php
   if ( false === ( $totd_trans_post_id = get_transient( 'totd_trans_post_id' ) ) ) {
        $args = array('numberposts' => 1, 'orderby' => 'rand');
        $totd = get_posts($args);
        $midnight = strtotime('midnight +1 day');
        $timenow = time();
        $timetillmidnight = $midnight - $timenow;
        echo $midnight;
        echo ",".$timenow;
        set_transient('totd_trans_post_id', $totd[0]->ID, $timetillmidnight);
   } else {
       $args = array('post__in' => array($totd_trans_post_id));
       $totd = get_posts($args);
   }
   
   foreach( $totd as $post ) : setup_postdata($post); ?>
       <div>
           <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
           <?php the_content(); ?>
       </div>
   <?php endforeach; ?>
   

   get_posts() help Plus the way I have coded it should make the Tip of the Day post change at midnight every day.

   This can be improved upon because we are showing random there is nothing stopping the same post showing twice in a row…

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2. A transient seems like a lot of extra effort. Instead, just use the fact that MySQL’s RAND function can be seeded for reproducible random numbers.

   Use a function like this:

   function force_random_day_seed($orderby) {
       $seed = floor( time() / DAY_IN_SECONDS );
       $orderby=str_replace('RAND()', "RAND({$seed})", $orderby);
       return $orderby;
   }
   

   Then, around your WP_Query or get_posts or whatever it is that you have retrieving this single post, use this filter code:

   add_filter('posts_orderby', 'force_random_day_seed');
   $args = array('numberposts' => 1, 'orderby' => 'rand');
   $totd = get_posts($args);
   remove_filter('posts_orderby', 'force_random_day_seed');
   

   This adds the filter, gets the post, then removes the filter.

   By setting the seed to a number that changes once a day, then the random will produce the same answer every time for that day. Then it will give a different random number every DAY_IN_SECONDS goes by.

   No transients, no need for storage of data.

   Update for WordPress 4.5+

   Ordering by random, containing a seed value, is now supported in WordPress 4.5+:

   $rand = sprintf( 'RAND(%d)', floor( time() / DAY_IN_SECONDS ) );
   $args = array( 'numberposts' => 1, 'orderby' => $rand );
   $totd = get_posts($args);
   

   See ticket #35692 for more information.

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3. You can use the Transients API, as kaiser said. Just store a random post ID with a lifetime of 24h. To select a random post you can set the orderby argument of get_posts() to "rand".

   Use case example:

   function wpse17056_twentyfour_sticky_post()
   {
       $transient = get_transient( 'twentyfour_sticky_post' );
   
       // set transient if none is present    
       if ( false === $transient ) 
       {
           $rand_post = get_posts( array( 'numberposts' => 1, 'orderby' => 'rand') ); 
           set_transient( 'twentyfour_sticky_post', $rand_post[0]->ID, DAY_IN_SECONDS );
       }
   }
   add_action( 'init', 'wpse17056_twentyfour_sticky_post', 0 );
   

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4. Interact with the Transients API. You could attach something like “sticky” to it or a specific category or term.

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