Related Posts (via tags or categories)

gistfile1.txt

/**
 * Setup the in-post related posts list
 */
function wds_threatpost_related_posts() {
  // Get tags, if they exist...
	$tags = wp_get_post_tags( get_the_ID() );
	if ( $tags ) {
		$tag_ids = array();
		foreach( $tags as $single_tag ) $tag_ids[] = $single_tag->term_id;

		$args = array(
			'tag__in' => $tag_ids,
			'post__not_in' => array( get_the_ID() ),
			'showposts'=> 3, //number of related posts
			'ignore_sticky_posts'=> 1
		);
	} else { // Or get categories
		$categories = get_the_category( get_the_ID() );
		if ( $categories ) {
			$category_ids = array();
			foreach( $categories as $single_category ) $category_ids[] = $single_category->term_id;

			$args = array(
				'category__in' => $category_ids,
				'post__not_in' => array( get_the_ID() ),
				'showposts'=> 3,  //number of related posts
				'ignore_sticky_posts'=>1
			);
		}
	}

	// Run the query
	if( $args ){
		$my_query = new wp_query( $args );
		if( $my_query->have_posts() ) :
			echo '<div class="related-posts-inner"><h3>'. __( 'Related Posts', 'kasp' ) .'</h3>';
			while ( $my_query->have_posts() ) : $my_query->the_post();
				if ( $my_query->current_post+1 == $my_query->post_count )
					$last = 'last';
				else
					$last = null; ?>
					<article id="post-<?php the_ID(); ?>" <?php post_class( array( 'secondary-post', $last ) ); ?>>
						<h4 class="entry-title">
							<a href="<?php the_permalink(); ?>" title="<?php echo esc_attr( sprintf( __( 'Permalink to %s', 'kasp' ), the_title_attribute( 'echo=0' ) ) ); ?>" rel="bookmark"><?php the_title(); ?></a>
						</h4>
						<div class="post-info">
							<span class="date"><?php echo the_time( get_option('date_format') ); ?> , <?php echo the_time( get_option('time_format') ); ?></span>
						</div>
					</article><!-- #post -->
			<?php endwhile;
			echo '</div>';
		endif;
		wp_reset_postdata();
	}
}