Displaying Related Category and Author Content in WordPress

View any single-post page from Mimbo Pro and you’ll notice two sidebar modules called “More from this category” and “More from this author”.

Why Is It Useful?

Pretend you’d discovered that story (“Kenya tourism, economy devastated by violence”) via random Google search. You might finish reading, know nothing else about the site, and hit your ‘Back’ button. As a designer, you want to help users explore topics in a forward or sideways motion from anywhere on the site. You can accomplish this by pulling in related content and providing logical jumping-off points, without requiring users to work backward.

Online newspapers like The Times use this principle. This article on Hillary Clinton is supported by smaller modules like political cartoons and related election coverage:

Politically-minded readers are now immersed in a topic they already enjoy, and are more likely to dig deeper into a whole section of the website rather than just one story. Good information-design connects the page to the interests of the user. Think of Pandora’s scrolling interface and the way it begins to ‘know’ your musical taste, compelling you to visit more often.

The Code

Here’s a simplified version of the code Ben wrote for Mimbo Pro, which must be included outside of the loop:

<?php

  //Gets category and author info
  global $wp_query;
$cats = get_the_category();
  $postAuthor = $wp_query->post->post_author;
$tempQuery = $wp_query;
  $currentId = $post->ID;
// related author posts
  $newQuery = "posts_per_page=5&author=" . $authorPosts;
  query_posts( $newQuery );
$authorPosts = "";
  $count = 0;
if (have_posts()) {
  while (have_posts()) {
  $count++;
  the_post();
  if( $count<4 && $currentId!=$post->ID) {
  $count++;
  $authorPosts .= '<li><a href="' . get_permalink() . '">' . the_title( "", "", false ) . '</a></li>';
  }
  }
  }
// related category posts
  $catlist = "";
  forEach( $cats as $c ) {
  if( $catlist != "" ) { $catlist .= ","; }
  $catlist .= $c->cat_ID;
  }
  $newQuery = "posts_per_page=5&cat=" . $catlist;
  query_posts( $newQuery );
$categoryPosts = "";
  $count = 0;
if (have_posts()) {
  while (have_posts()) {
  the_post();
  if( $count<4 && $currentId!=$post->ID) {
  $count++;
  $categoryPosts .= '<li><a href="' . get_permalink() . '">' . the_title( "", "", false ) . '</a></li>';
  }
  }
  }
  $wp_query = $tempQuery;
  ?>

Then inside the loop, call the functions like this:

<h4>More from this category</h4>
<ul>
<?php echo $categoryPosts; ?>
</ul>
<h4>More from this author</h4>
<ul>
<?php echo $authorPosts; ?>
</ul>

How’s it Work?

This whole task would be easy if we were pulling from a single static category or author. The query_posts function offers simple parameters. But pulling that information dynamically is slightly trickier.

Ben explains further:

All we need is work out which category/author the post is in and use that data to get the information. 5 posts are grabbed – then, when looping through the posts, we double check to make sure that the current post is not being linked to redundantly (this feature is not currently in Mimbo Pro but will be in the next update).

Because of the layout of the theme, we need to do all of this before the post is displayed. At the time I found the easiest method was to save the current page’s data as a new variable ($tempQuery = $wp_query;), do all the work, and then reassign the values so that the page can be updated as normal. This works great, but if I was to write it again I would use a new instance of the wp_query object, as described here by Ronald Huereca.

No matter how you code it, supporting your posts with related content is valuable to readers who want additional context and to bloggers who want a stickier site.