Just in case someone should need it:
function send_to_streicher()
{
mailusers_register_group_custom_meta_filter('Aktive Streicher', 'streicher',1,"=");
}
function update_active_strings_meta_filter(){
$newkey = 'streicher' ;
$searchkey = 'instrument';
$searchvalues = array(
'Kontrabass','Cello','Violine I','Violine II','Viola'
) ;
update_active_register_meta_filter($searchkey,$searchvalues,$newkey);
}
function update_active_register_meta_filter($searchkey,$searchvalues,$newkey)
{
$uq = new WP_User_Query(array('meta_key' => $newkey)) ;
foreach ($uq->get_results() as $u)
delete_user_meta($u->ID, $newkey) ;
foreach ($searchvalues as $val)
{
$args = array(
'meta_query' => array(
0 => array(
'key' => $searchkey,
'value' => $val,
),
1 => array(
'key' => 'status',
'value' => 'Aktiv'
)
));
$uq = new WP_User_Query($args) ;
foreach ($uq->get_results() as $u){
update_user_meta($u->ID, $newkey, true) ;
}
}
}