If you need the ids separated by coma you can get them from the array you have:
$listids = implode ( "," , $postids );
In any case, please provide more info or code about what you need
If you need the ids separated by coma you can get them from the array you have:
$listids = implode ( "," , $postids );
In any case, please provide more info or code about what you need