Display two previous posts on single.php

Question

At the bottom of single.php, I want to display "card" links to the next and previous posts in chronological order. This is pretty easy thanks to get_next_post() and get_previous_post, no problems so far.

However, I want to change that feed when on the most recent post -- that post won't have a next post. Instead of an empty space in my layout, I'd like to display the previous post and its previous post. So the two previous posts instead of just one.

I know how to check if we're on the most recent post, I'm just not sure how to properly call the multiple previous posts. My basic code structure is:

if ( have_posts() ) {
     while ( have_posts() ) { the_post();
          // output current post here
     }

     $next = get_next_post();
     if( $next ) {
          $id = $next->ID;
          $url = get_the_permalink( $id );
          $title = $next->post_title;
          $date = get_the_date( '', $next );
          // use these variables to output link to next post
     }

     $prev = get_previous_post();
     if( $prev ) {
          $id = $prev->ID;
          $url = get_the_permalink( $id );
          $title = $prev->post_title;
          $date = get_the_date( '', $prev );
          // use these variables to output link to previous post
     }

     // If there's no next post, that means we're on the most recent post.
     // To fill the space, let's pull the 2nd previous post.
     if( !$next ) {
          // Make sure there's a previous post
          if( $prev ) {

               // Conditions are perfect. Now how do I grab that 2nd previous post??

          }
     }
 }

I'm sure it's some basic query issue. What am I missing?

Answer 1

I hope there are multiple ways to accomplish this, but I suggest you use the following simpler function for this purpose. This is an attempt to grab a post for the current post which excludes it and the previous post:

// A custom function in your functions.php file
function get_related_previous_post($previous = 0) {

    global $post; // take current post object
    $category_ids = array();
    $categories = get_the_category($post->ID); // current post categories
    
    if ($categories) {
        foreach ($categories as $individual_category) {
            $category_ids[] = $individual_category->term_id;
        }
    }

    $args = array(
        'post__not_in' => array($post->ID, $previous), // exclude posts
        'posts_per_page' => '1',
        'orderby' => 'date',
        'order'   => 'DESC',
        'category__in' => $category_ids // apply same categories 
    );
    $prevprev_id = 0;
    $my_query = new WP_Query( $args );
    if ($my_query->have_posts()) {

        while ($my_query->have_posts()) {
            $my_query->the_post();
            // Do your stuff
            $prevprev_id = $post->ID;
        }
    }
    wp_reset_postdata();
    return get_post($prevprev_id);
}

Call the function in your single.php file like:

if (!$next) {
    // Make sure there's a previous post
    if ($prev) {
        $prevprev = get_related_previous_post($prev->ID);
    }
}