Combining WordPress Post Queries With Options

Ah WordPress queries, how convenient and expandable they are.  I’ve been working with some pretty big queries lately and I’ve been very impressed with how well WordPress has handled them.  Very clean and very fast.  Last week, I had the need to combine two post queries which I have done a couple times in the past, but this instance posed a second challenge: they needed to be re-ordered after combining.  After thinking through several different options, here’s what I came up with.  In short, we’re going to take two queries, merge the arrays, remove duplicates, and then re-query the posts using ‘post__in’.  In the re-query, we can also set ordering rules.  Let’s jump into the code:

Query 1:

$studentposts = get_posts(array(
    'post_type' => 'student',
    'post_status' => 'publish',
    'cat' => 'books',
));	

Query 2:

$busposts = get_posts(array(
    'post_type' => 'business',
    'post_status' => 'publish',
    'cat' => 'wholesale',
));	

Combine & Get Unique

$mergedposts = array_merge( $studentposts, $busposts );
$postids = array();
foreach( $mergedposts as $item ) {
$postids[]=$item->ID; 
}
$uniqueposts = array_unique($postids); //remove duplicate post ids

Re-Query With Order

if(!empty($uniqueposts)) {
	$args = array(
		'post__in' => $uniqueposts,  
	    'post_type' => 'any',
	    'post_status' => 'publish',
	    'orderby' => 'title',
	    'order' => 'ASC'
	);
	$the_query = new WP_Query( $args );
	if( $the_query->have_posts() ): 
		while( $the_query->have_posts() ) : $the_query->the_post();
			// Do stuff here
		endwhile;
	endif; wp_reset_query();
}

And that’s how we can combine two post queries and then re-order them!