Silverstripe add/save object to has_one relation

Question

I cannot find a clue on how to correctly save a has_one relation in Silverstripe.

class Car extends DataObject {
  $has_one = array(
     'garage'=>'Garage';
  );
}

class Garage extends DataObject {
  $has_many = array(
     'cars'=>'Car';
  );
}
// let's say I have these records in the DB
$g = Garage::get()->ByID(111);
$c = Car::get()->ByID(222);

// I want to do sth like this to define the relation
$c->Garage = $g;
$c->write();

But this code does nothing, no error, but also the relation is not created in the DB.

What I could to is this:

$c->GarageID = $g->ID;
$c->write();

But this does not seem very ORM like...

Answer 1

there doesn't seem to be an extra method for adding has_one relations, but if you want to stick with the ORM, you could do it the other way around:

$g->cars()->add($c);