LINQ查詢這種情況

Question

我有以下兩個接口：

public interface IShipment
{
    IEnumerable<IShippedItem> Contents { get; }
    string InvoiceNumber { get; }
}

public interface IShippedItem
{
    string ProductCode { get; }
    int Quantity { get; }
}

現在，我正在嘗試編寫LINQ語句，以使我僅獲得ProductCode的列表。

怎么辦呢？

IEnumerable<IShipment> shipments = GetShipments();
var productCodeList = from shipment in shipment
                      ???????

Answer 1

您可以使用SelectMany展平內容，然后僅使用Select並獲取每個IShippedItem的ProductCode 。

var productCodes = shipments
                   .SelectMany(x => x.Contents)
                   .Select(x => x.ProductCode)
                   .ToList();

Answer 2

我的錯，我提早提交，這里是：

from shipment in shipments 
from shippedItem in shipment.Contents  
select shippedItem.ProductCode