Custom Taxonomy – Related Posts Query

I ended up rolling my own function for this task based on the get_the_category() function. Basically, it uses the wp_get_object_terms() function and adds some caching. I haven’t tested it extensively, but it’s been working for me so far.

function get_the_taxonomy( $taxonomy, $id = false ) {
	global $post;

	$id = (int) $id;
	if ( !$id )
		$id = (int) $post->ID;

	$categories = get_object_term_cache( $id, $taxonomy );
	if ( false === $categories ) {
		$categories = wp_get_object_terms( $id, $taxonomy );
		wp_cache_add($id, $categories, $taxonomy.'_relationships');
	}

	if ( !empty( $categories ) )
		usort( $categories, '_usort_terms_by_name' );
	else
		$categories = array();

	foreach ( (array) array_keys( $categories ) as $key ) {
		_make_cat_compat( $categories[$key] );
	}

	return $categories;
}

Hope that helps you out!

Chris

When I tried that out in twenty ten, I got this error message:
Warning: Missing argument 1 for get_the_taxonomy(), called in /home1/englisi9/public_html/testblog/wp-content/themes/twentyten/getthetax.php on line 8 and defined in /home1/englisi9/public_html/testblog/wp-content/themes/twentyten/functions.php on line 485

Warning: array_keys() [function.array-keys]: The first argument should be an array in /home1/englisi9/public_html/testblog/wp-content/themes/twentyten/functions.php on line 503

Would love to see it work.

Hi,

I’m using this code to retrieve related posts based on my custom taxonomy. It works great, but the only problem is that I’m trying to retrieve a total of 4 related posts. This retrieves up to 4 posts per term. What am I doing wrong?

<?php
global $post;
$terms = get_the_terms( $post->ID , 'badge', 'string');
$do_not_duplicate[] = $post->ID;
$postnum = 0;

if(!empty($terms)){
    foreach ($terms as $term) {
        query_posts( array(
        'badge' => $term->slug,
        'showposts' => 3,
        'caller_get_posts' => 1,
        'post__not_in' => $do_not_duplicate ) );
        if(have_posts()){ ?>

            <?php while ( have_posts() ) : the_post(); $do_not_duplicate[] = $post->ID; ?>
		<?php $postnum++; ?>
	<div class="single-small-posts-<?php echo $postnum; ?>">
      			<?php
			$clipping_image = get_post_meta( $post->ID, 'clipping_image', true );
			$terms_of_post = get_the_term_list( $post->ID, 'type', '','', '', '' );?>

			<a href="<?php the_permalink() ?>" rel="bookmark" title="<?php the_title();?>"><img src="<?php bloginfo('template_directory'); ?>/scripts/timthumb.php?src=<?php echo $clipping_image ?>&h=140&w=140&zc=1"></a>
				<p class="single-small-post-cat"><?php if( $terms_of_post ) echo $terms_of_post; ?></p><p class="single-small-post-number">#<?php echo get_post_meta($post->ID,'incr_number',true); ?></p>

		</div>
        		<?php $found_none = '';
     			endwhile; wp_reset_query();
?>

    <?php }
  }
}
if ($found_none) {
echo $found_none;
}
$post = $backup;  // copy it back
wp_reset_query(); // to use the original query again
?>

Hello,

I tried fcarthy’s code but it throws back a bunch of posts even if they aren’t using taxonomy terms…

I only have one post that uses one of my “Brands” taxonomy terms, so this script should only return one post. I don’t understand how its fetching the results.

I am trying to display related “posts” on a custom post type’s single.php template, based on wether or not the posts are associated with at least one of the same terms (in my Brands taxonomy) as the current custom post.

Does someone know how to do this? I just can’t get this to work properly.
Thanks,
C.

@fcarthy, @mistercyril

Just taking a quick look at that code, if you want it to just print the first 4 posts that it finds, I think you can simply add this to the beginning of the foreach loop:

if($postnum >= 4) break;

Not tested or anything, but I hope that helps.

@fcarthy, yes that is correct.

If you want be “fair” with the tag distribution, you’d want to collect 4 potential posts from each tag in arrays and then loop through each until you have enough. You might do something like this:

$potentials = array();
$c = 0;
$totalFound = 0;
//Gather your posts for each term
foreach($terms as $term_name){
   $q = array(
	'my_custom_tax' =>	$term_name,
	'numberposts' => 4
   );
   $posts = get_posts($q);
   $totalFound+= count($posts);
   $potentials[$c++] = array_reverse($posts);
}
$count = 0;  //The number of good posts we've found
$index = 0;  //Number of posts we've tried
$max = $totalFound > 4 ? 4 : $totalFound;
$posts = array();
//Now pick one post from each term until we reach our quota, or have checked them all
while($count < $max){
  //Pop off a post to use
  $post = array_pop($potentials[$index++]);
  //only works if there is a post left in this array
  if($post){
    //don't take duplicates
    if($empty($posts[$post->ID])){
      $posts[$post->ID] = $post;
      $count++;
    }
  }
  $index = ($index % 4);
}
foreach($posts as $post){
  //print your posts
}

This is off the top of my head and untested, but it’s something to play with at least 🙂

Yeah, the code isn’t complete. It’s assumed you already have $terms in an array to loop through. You could test it by setting:

$terms = array( 'term1', 'term2', 'term3' );

at the top.

my_custom_tax should get replaced with the slug of the custom taxonomy (most likely ‘brands’ not ‘Brands’)

To limit the post type just set ‘post_type’ => ‘post’ in the $q array.