How to rearrange a pool of posts joined using two queries?

Question

I need to select posts for two different months (current, past). As far as i know, it is not possible to pass m date parameter as an array of integer instead of an integer, so I am performing two different queries and getting all posts returned into the same array.

The question is, how do i reorder the result pool of posts? Just pushing the second pool into the array returned by the first query isn't enough, as the orderby argument finds a discontinuity in the joint of the two arrays.

I tried using usort but I get an error saying that You can't use WP_Post object as an array.

Any ideas?

Thanks,

Answer 1

This is how I would approach it:

Code

function my_pseudo_date_query( $where, $query ) {

    global $wpdb;

    $dq = $query->get('my_date_query');

    if( $dq && !empty( $dq['after'] ) ){

        $where .=  $wpdb->prepare( 
                      " AND {$wpdb->posts}.post_date >= %s"
                      $dq['after']
                   );
    }

    if( $dq && !empty( $dq['before'] ) ){

        $where .=  $wpdb->prepare( 
                     " AND {$wpdb->posts}.post_date <= %s",
                      $dq['before']
                   );
    }

    return $where;
}
add_filter( 'post_where', 'my_pseudo_date_query', 10, 2 );

Example usage:

$now = new DateTime( 'now' );
$first_of_last_month = new DateTime( 'first day of last month' );
$my_query = new WP_Query( array(
 'my_date_query' => array(
      'before' => $now->format( 'Y-m-d H:i:s' ),
      'after' => $first_of_last_month->format( 'Y-m-d H:i:s' ),
  );
 ) );

The before argument is redundant in this example.

Remarks

1. This hasn't been tested, it's code 'in principle'.
2. I've been quite lazy here and the before and after keys of the my_date_query attribute are quite strict. They must be in the Y-m-d H:i:s (php) format. But it's enough for this answer.
3. As noted in the comments WordPress 3.7 will provide date_query as an argument. The above code is 'forward compatible' in the sense that once you've upgraded to 3.7, you can remove the my_ prefix from the example.
4. The example assumes PHP5.3+. Though its fairly simple to workaround this limitation.
5. If using with get_posts() don't forget to set suppress_filters to false.