如何使用c#mvc获取表1中的所有id并保存到表2中？

我是这里的新手。我使用的是c#MVC5。
我将尝试在表1中获取所有状态为“已拾取”的id，并保存到表2中

这是我的错误

无法将类型为“WhereSelectListIterator`2[ChenvelIntl.Core.Domain.Packages.Package，System.Int32]”的对象强制转换为类型为“System.IConvertible”

这是我的密码。但它不起作用。有人能帮我解决这个问题吗

var package = _packageService.GetAll().Where(x => x.Status == "Picked-up");

var shipmentItem = new ShipmentItem
{
    ShipmentId = model.ShipmentId
};

if (package != null)
{
    shipmentItem.PackageId = Convert.ToInt32(package.Select(x => x.Id));
}
_shipmentItemService.Add(shipmentItem);
return RedirectToAction("addshipmentitem");

---

package

变量将包含一个

WhereSelectListIterator

或一个链接到多个包的对象

将其更改为

.First（）

，例如

var package = _packageService.GetAll().First(x => x.Status == "Picked-up");

然后在下面：

// If package.Id is not an Int32 already...
shipmentItem.PackageId = Convert.ToInt32(package.Id);

如果需要全部，请按如下方式更改代码：

   var packages = _packageService.GetAll().Where(x => x.Status == "Picked-up").ToArray().Where(x => x != null).ToArray();
                  foreach(var package in packages) {
                    var shipmentItem = new ShipmentItem
                    {
                        ShipmentId = model.ShipmentId,
                        PackageId = Convert.ToInt32(package.Id)
                    };

                    _shipmentItemService.Add(shipmentItem);
                   }
                    return RedirectToAction("addshipmentitem");

就这么做吧：

     var shipmentItems= _packageService.GetAll()
                        .Where(x => x.Status == "Picked-up")
                        .Select(x=>new ShipmentItem(){ShipmentId = x.ShipmentId , PackageId=int.Pars(x.Id)});

     if(shipmentItems.Any())
    _shipmentItemService.Add(shipmentItems);   

    return RedirectToAction("addshipmentitem");

如果_shipmentItemService.Add（）只收到一个要添加的shipmentItem，请执行以下操作：

shipmentItems.ToList().ForEach(x=>_shipmentItemService.Add(x))

您将获得一个整数数组packageId 然后循环抛出数组并逐个添加装运项目。。 我希望它能奏效

 foreach (var packageId in packageIds)
                {
                    var shipmentItem = new ShipmentItem
                    {
                        ShipmentId = model.ShipmentId,
                        PackageId = Convert.ToInt32(packageId)
                    };
                    _shipmentItemService.Add(shipmentItem);

                }

---

如果您将函数拆分并将

var

更改为实际类型，您将立即看到您的问题：

IEnumerable<Package> fetchedPackages = _packageService.GetAll();
IEnumerable<Package> pickedUpPackages = fetchedPackages
   .Where(package => package.Status == "Picked-up");

---

注意：如果没有此类pickedUpPackageId，则无论何时出现错误，该值都将为零

，请务必在哪一行告诉我们。您好，谢谢您的回复。如果我把它改成。首先我得到1个值。我需要获取状态为“已拾取”的所有id，并将所有id保存在表2中。@DenmarkDelPuso问题中的每个答案旁边都应该有一个复选标记，单击它将把答案标记为已接受。

IEnumerable<Package> fetchedPackages = _packageService.GetAll();
IEnumerable<Package> pickedUpPackages = fetchedPackages
   .Where(package => package.Status == "Picked-up");

IEnumerable<int> pickedUpPackageIds = pickedupPPages
    .Select(pickedUpPackage => pickedUpPackage.Id);
shipmentItem.PackageId = Convert.ToInt32(pickedUpPackageIds);

int pickedUpPackageId =  _packageService.GetAll()
    .Where(package => package.Status == "Picked-up")
    .Select(package => package.Id)
    .FirstOrDefault(); // or SingleOrDefault

shipmentItem.PackageId = Convert.ToInt32(pickedUpPackage.Id);