Re-order a taxonomy archive page using a custom field

Ok this one sounds a bit like tapping your head while doing circles on your stomach but it’s one that I’ve come across a couple of times now.

Normally when you have a taxonomy archive page it will do the usual thing of ordering that archive page with the last post first etc..

So how do you go about changing the sort order?

I’ve got a custom field which is a date – DepDate it is in the format of 20120329 (Year Month Date) and I want to sort the posts via that date rather than the post date. This would also work if it was say an alphabetical search on a custom field.

So the approach is to interrupt the loop and enter your own criteria to the $wp_query so in the example I was using the Genesis Framework so I’ve hooked this before the content using ‘genesis_before_content’ 

Then using array_merge you append your own arguments into the default loop.

function tourCustomPost(){
	if(is_tax('tourtype') ){

	$today = date('Ymd');
	global $wp_query;
	$args = array_merge( $wp_query->query, array(
	'posts_per_page' => 10,
	'meta_key' => 'DepDate' ,
	'orderby' => 'meta_value',
	'order'=>'ASC'
	) );
	query_posts( $args );
	//echo "<h1>hello</h1>";
	//echo $today;
	} // end of containing if
}

add_action('genesis_before_content', 'tourCustomPost');