// Get custom taxonomies
// Get array of taxonomies eg activity, difficulty, subject
$taxonomies = get_taxonomies( array('_builtin' => false, 'public' => true),'objects' );
// foreach taxonomy, get a list of options to sort by, terms, eg maths, science
foreach ( $taxonomies as $tax => $tax_obj ){
$terms[$tax_obj->query_var] = get_terms($tax_obj->name); // array of terms
}
// check stuff in GET is a registered taxonomy
$tax_args = array();
foreach ( $_GET as $key => $val ){
if( array_key_exists($key, $terms) ){
// if its set, add an argument for get_posts
if( $val ){
$tax_args[$key] = $val;
}
}
}
// build lines of conditions for if there are taxonomical requirements in the query string
$sort_conditions = '';
$required_matches = -1;
if( count( $tax_args ) ){
$sort_conditions.= " WHERE 0=1 "; // add this so other stuff can just repeat ORs
foreach( $tax_args as $key => $slug ){
$sort_conditions.= " OR taxonomy = '$key' AND slug = '$slug' ";
$required_matches ++;
}
}
$sql ="
SELECT count(1) AS matches,t1.* FROM(
SELECT wp_posts.*, wp_term_taxonomy.taxonomy, wp_terms.slug
FROM wp_posts
LEFT JOIN wp_term_relationships ON(wp_posts.ID = wp_term_relationships.object_id)
LEFT JOIN wp_term_taxonomy ON(wp_term_relationships.term_taxonomy_id = wp_term_taxonomy.term_taxonomy_id)
LEFT JOIN wp_terms ON(wp_term_taxonomy.term_id = wp_terms.term_id)
JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id)
WHERE wp_posts.post_type = 'post'
AND (wp_posts.post_status = 'publish')
AND wp_postmeta.meta_key = 'priority'
AND wp_posts.post_status = 'publish'
ORDER BY wp_postmeta.meta_value ASC, wp_posts.post_date DESC
LIMIT 0, 999) AS t1
$sort_conditions
GROUP BY ID HAVING matches > $required_matches";
$listing = $wpdb->get_results( $sql );