I'll give it a shot. Let's take them one at a time:
Method 1
$converter=Mage::getModel('sales/convert_order');
$shipment=$converter->toShipment($order);
$converter
above is loaded from the class Mage_Sales_Model_Convert_Order
, which uses a core helper called copyFieldset
to copy order details into a shipment object. $order has to be of type array or Varien_Object
.
This method is actually at the core of Method 3, as it uses Mage::getModel('sales/convert_order')
in its constructor call.
Key differentiator of this method - it can take an array or an object $order
and generate a basic $shipment
object. It is a lower-level method used exclusively by the methods you put forth in Method 2, Method 3.
Method 2
$shipment = Mage::getModel('sales/service_order', $order)
->prepareShipment($this->_getItemQtys($order));
This seems to be the most popular way in Magento's Core of generating a shipment as it is used in both Shipment and Invoice controllers. $order
is used as a constructor argument to the instantiation of Mage_Sales_Model_Service_Order
, setting it as a protected property on the object.
You're then calling prepareShipment
and passing a quantity. As this method uses the converter class from Method 1, you needn't specify more details such as order items pass item shipment qty details in the prepareShipment
argument, called here with $this->_getItemQtys
. To use this on your own context, all you need to do is pass the quantity of items in an array with the following format:
array(
'order_item_id'=>$qty,
'order_item_id'=>$qty,
'order_item_id'=>$qty
)
Key differentiator of this method - it gives you back a $shipment object, but with all items converted on it. It's plug-and-play.
Method 3
I could not find evidence of using this method in the Core. It looks like a hack, to be honest. Here's the method:
$itemQty = $order->getItemsCollection()->count();
$shipment = Mage::getModel('sales/service_order', $order)->prepareShipment($itemQty);
$shipment = new Mage_Sales_Model_Order_Shipment_Api();
$shipmentId = $shipment->create($orderId);
Step 1 is exactly the same as Method 2 above. No difference. However, you get back a $shipment
object, which is replaced by a direct insantiation of Mage_Sales_Model_Order_Shipment_Api
. This is non-standard. The best-practice way of getting a shipment Api object would be to call Mage::getModel('sales/order_shipment_api')
.
Next, it uses that overwritten, new Shipment API object to create a shipment from an $orderId
variable that hasn't been defined in your code. Again, this seems like a workaround.
Looking at Mage_Sales_Model_Order_Shipment_Api::create()
, it seems like a one-stop-shop for generating a shipment as the most basic details needed to create the shipment is only an order increment_id
.
This is a hack that shouldn't be used by any module or extension. This API is meant to be consumed by features exposed via XML RPC / SOAP API requests and is intentionally basic to eliminate multiple step API requests.
Eventually Method 3 gets to the nitty-gritty, though, and via a call to Mage_Sales_Model_Order, it calls prepareShipment
, which is a higher-order abstraction for the familiar Method 2 above:
public function prepareShipment($qtys = array())
{
$shipment = Mage::getModel('sales/service_order', $this)->prepareShipment($qtys);
return $shipment;
}
Key differentiator here - if you need a shipment, don't mind hacks, and only have an increment_id - use this method. Also useful information if you prefer to handle this via the SOAP API.
I hope that helps.