Retrieve all post meta for a given $key by $post_type. This function is useful if you need to do any front-end sorting of posts by meta key/values and need to populate a select
/**
* Retreive all post meta for a given $key by $post_type
*
* This function is useful if you need to do any frontend sorting of posts by meta key/values and need to populate a select
*
* @param string
* @param string
* @param string
* @param bool
* @return array
*/
function get_meta_values( $key = '', $post_type = 'post', $status = 'publish', $remove_duplicates = TRUE ) {
global $wpdb;
if( empty( $key ) )
return;
$r = $wpdb->get_col( $wpdb->prepare( "
SELECT pm.meta_value FROM {$wpdb->postmeta} pm
LEFT JOIN {$wpdb->posts} p ON p.ID = pm.post_id
WHERE pm.meta_key = '%s'
AND p.post_status = '%s'
AND p.post_type = '%s'
", $key, $status, $post_type ) );
if( $remove_duplicates )
return array_unique( $r );
return $r;
}