Custom PK->FK association

[OmgDef]

I have a problem with saving related model.

Order model :

            'customer' => array(self::HAS_ONE, 'Customer', array('id' => 'customer_id')),

Customer model:

            'orders' => array(self::HAS_MANY, 'Order', 'customer_id'),

Controller:

        if (isset($_POST['Order'])) {
            $model->attributes = $_POST['Order'];
            if (isset($_POST['Customer']))
                $model->customer->setAttributes($_POST['Customer']);

            if ($model->withRelated->save(true, array('customer')))
                $this->redirect(array('admin'));
        }

After save customer_id property of Order is NULL.