如何使用C＃MVC获取table1中的所有ID并保存到table2？

Question

I'm a newbie here. I'm using c# MVC 5.
I'll try to get all id with status of "Picked-up" in table1 and save into table2

this is my error.

Unable to cast object of type 'WhereSelectListIterator`2[ChenvelIntl.Core.Domain.Packages.Package,System.Int32]' to type 'System.IConvertible'.

This is my code. but But it's not working. Can someone help me on how to solve this?

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");

Answer 1

Your package variable would contain a WhereSelectListIterator or an object that links to MANY packages.

Change it to .First() , eg

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

and then below:

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

If you need all, change the code like so:

   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");

Answer 2

just do it :

     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");

if _shipmentItemService.Add() only receives one shipmentItem to add , do this :

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

Answer 3

int[] packageIds = _packageService.GetAll().Where(x => x.Status == "Picked-up").Select(x=>x.Id).ToArray();

your will get an int array of packageids then loop throw the array and add your shipment item one by one.. I hope it will work..

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

                }

Answer 4

If you would split your functions and change var into the actual types, you would immediately see your problem:

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

and later:

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

It is easy to see that Convert.ToInt32 does not know how to handle a sequence of pickedUpPackageIds

What you should change, depends on what you want.

From the identifier name, I get the impression that you expect that there is at utmost one Package with status "Picked-Up":

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

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

Note: if there is no such pickedUpPackageId, the value will be zero