相关疑难解决方法(0)

使用LINQ从列表中获取数据时遇到此错误.怎么解决这个问题？

值不能为空.参数名称:source

var nCounts = from sale in sal
              select new
              {
                  SaleID = sale.OrderID,
                  LineItem = from sli in sale.LineItems
                             group sli by sli.Item into ItemGroup
                             select new
                             {
                                 Item = ItemGroup.Key,
                                 Weeks = ItemGroup.Select(s => s.Week)
                             }
              };

foreach (var item in nCounts)
{
    foreach (var itmss in item.LineItem)
    {
        // MessageBox.Show(itmss.Item.Name);
        itemsal.Add(new Roundsman.BAL.WeeklyStockList(itmss.Item.Name.ToString(),
                    itmss.Item.Code.ToString(),
                    itmss.Item.Description.ToString(),
                    Convert.ToInt32(itmss.Item.Quantity), 2, 2, 2, 2, 2, 2, 2, 2, 2));
    }                      
}

执行后我得到的错误我的LINQ我得到了那种类型的结果(一行,orginally):

System.Linq.Enumerable.WhereSelectListIterator <Roundsman.BAL.Sale,<> f__AnonymousType1 <int,System.Collections.Generic.IEnumerable <<> f__AnonymousType0 <Roundsman.BAL.Items.Item,System.Collections.Generic.IEnumerable <Roundsman. BAL.WeeklyRecord …