CQRS & PurchaseOrder AggregateRoot

Question

我是CQRS和DDD的新手，我正在使用MS WideWorldImporters数据库，目前我被困在定购订单放置命令上，说出我不知道它应该是什么样子的真相，你能指导我吗？如果我有一个PlaceOrderCommand，而处理程序应该使用它来创建PurchaseOrder、填充它的OrderLines并进行保存。如果是，命令应该是什么样子的域模型时：

样本域模型：

public class PurchaseOrder : AggregateRoot<int>
{
    private PurchaseOrder(int id, int supplierID, DateTime orderDate, int deliveryMethodID, int contactPersonID) : base(id)
    {
        SupplierID = supplierID;
        OrderDate = orderDate;
        DeliveryMethodID = deliveryMethodID;
        ContactPersonID = contactPersonID;
    }

    public List<PurchaseOrderLine> PurchaseOrderLines { get; private set; }
    public int SupplierID { get; private set; }
    public DateTime OrderDate { get; private set; }
    public int DeliveryMethodID { get; private set; }
    public int ContactPersonID { get; private set; }

    public static PurchaseOrder CreatePurchaseOrder(int supplierID, int deliveryMethodID, int contactPersonID)
    {
        return new PurchaseOrder(1, supplierID, DateTime.Now, deliveryMethodID, contactPersonID);
    }

    public void AddPurchaseOrderLine(int stockItemID)
    {
        PurchaseOrderLines.Add(new PurchaseOrderLine(this.Id, stockItemID));
    }
}

示例命令处理程序：

    public class PurchaseOrdersCommandHandler : 
    ICommandHandler<PlacePurchaseOrder>
{
    private readonly IPurchaseOrderRepository purchaseOrderRepository;

    public PurchaseOrdersCommandHandler(IPurchaseOrderRepository purchaseOrderRepository)
    {
        this.purchaseOrderRepository = purchaseOrderRepository;
    }

    public void Handle(PlacePurchaseOrder command)
    {
        // TODO: based on command Create Purchase order with its line items and save it to db as a whole
    }

}

Answer 1

你就不能这样做吗？

public void Handle(PlacePurchaseOrder command)
{
    var purchaseOrder = PurchaseOrder.CreatePurchaseOrder(command.id, command.upplierID, command.orderDate, command.deliveryMethodID, command.contactPersonID);
    foreach(int stockItemID in command.OrderLines)
    {
        purchaseOrder.AddPurchaseOrderLine(stockItemID)
    }
    this.purchaseOrderRepository.Save(purchaseOrder);
}