WordPress: uno shortcode per i post correlati

Gli shortcode di WordPress semplificano di molto la vita quando si tratta di aggiungere dei contenuti extra ai nostri post o alle nostre pagine. Vediamo come visualizzare i post correlati utilizzando uno shortcode.

Aggiungiamo il seguente codice al file functions.php:

function related_posts_shortcode( $atts ) {
	extract(shortcode_atts(array(
				'limit' => '5',
			), $atts));

	global $wpdb, $post, $table_prefix;

	if ($post->ID) {
		$retval = '<ul>';
		$tags = wp_get_post_tags($post->ID);
		$tagsarray = array();
		foreach ($tags as $tag) {
			$tagsarray[] = $tag->term_id;
		}
		$tagslist = implode(',', $tagsarray);


		$q = "SELECT p.*, count(tr.object_id) as count
			FROM $wpdb->term_taxonomy AS tt, $wpdb->term_relationships AS tr, $wpdb->posts AS p WHERE tt.taxonomy ='post_tag' AND tt.term_taxonomy_id = tr.term_taxonomy_id AND tr.object_id  = p.ID AND tt.term_id IN ($tagslist) AND p.ID != $post->ID
				AND p.post_status = 'publish'
				AND p.post_date_gmt < NOW()
 			GROUP BY tr.object_id
			ORDER BY count DESC, p.post_date_gmt DESC
			LIMIT $limit;";

		$related = $wpdb->get_results($q);
		if ( $related ) {
			foreach($related as $r) {
				$retval .= '<li><a title="'.wptexturize($r->post_title).'" href="'.get_permalink($r->ID).'">'.wptexturize($r->post_title).'</a></li>';
			}
		} else {
			$retval .= '
	<li>Nessun articolo correlato</li>';
		}
		$retval .= '</ul>';
		return $retval;
	}
	return;
}
add_shortcode('related_posts', 'related_posts_shortcode');

Quindi usiamo lo shortcode in questo modo:

[related_posts]