Filter Custom Post Type, Taxonomy by date archives

custom_post_type_taxonomy_date_archives.php

/* 

Problem was, a custom post type, with custom taxonomy, and then wanted to have a dropdown of archives by month/year. wp_get_archives() wouldn't work clearly. 

Rewrite rule required to be added: 

$new_rule = 'media-centre/format/media-releases/archives/(.+)/(.+)/?$' => 'index.php?post_type=mc&mc-format=media-releases&year=' . $wp_rewrite->preg_index(1) .'&monthnum=' . $wp_rewrite->preg_index(2); 

*/   

   /*
    *  Dropdown of media releases grouped by date.
    */
    function media_releases_dropdown()
    {
        $args = array( 
            'post_type' => 'mc',
            'mc-format' => 'media-releases',
            'posts_per_page' => -1
        );
        
        add_filter( 'posts_clauses', array('Dr', 'filter_query' ) ); 
        
        $archives = new WP_Query( $args );
        
        remove_filter( 'posts_clauses', array('Dr', 'filter_query' ) ); 
        
        $months = array();

        // Loop through the posts, and group into a year-month array for the dropdown.
        foreach ( $archives->posts as $record ){
            $key = date( 'Y/m', strtotime( $record->post_date ) );
            $val = date( 'F Y', strtotime( $record->post_date ) );
            $months[ $key ] = $val;
        }
        
        echo '<h3>Filter by Month</h3>';
        echo '<form id="month-filter"><select name="theurl" id="theurl" onchange="window.location.href=this.form.theurl.options[this.form.theurl.selectedIndex].value">';
        echo '<option value="/media-centre/format/media-releases/">-- All --</option>';
        
        foreach( $months as $k=>$v){
            
            // Set if current
            list($y,$m) = explode('/',$k);
            $selected =  ( $m == get_query_var('monthnum') && $y == get_query_var('year') ? 'selected="selected"' : '' );

            // Set URL to redirect to
            $k = get_bloginfo('url') . '/media-centre/format/media-releases/archives/' . $k . '/';
            
            // Echo the option
            echo "<option value=\"$k\" $selected>$v</option>";
        }
        echo '</select></form>';
    }
    
    function filter_query( $var )
    {
        $var['groupby'] = 'YEAR( wp_posts.post_date ), MONTH( wp_posts.post_date )';
        return $var;
    }