MARS in SQL Server 2000 - asp.net-mvc

Question

I am working in ASP.Net MVC 1.0 and SQL Server 2000 using Entity Framework.
My faulty controller code is given below:
int checkUser = id ?? 0;
string userNameFromNew, userNameToNew;
if (checkUser == 1)
{
userNameFromNew = "U" + Request.Form["usernameFrom"];
userNameToNew = "U" + Request.Form["usernameTo"];
}
else
{
userNameFromNew = "C" + Request.Form["usernameFrom"];
userNameToNew = "C" + Request.Form["usernameTo"];
}
var rMatrix = from Datas in repository.GetTotalRightData()
where Datas.UserName == userNameFromNew.Trim()
select Datas;
Right_Matrix RM = new Right_Matrix();
foreach(var Data in rMatrix)
{
RM.Column_Id = Data.Column_Id;
RM.ProMonSys_Right = Data.ProMonSys_Right;
RM.UserName = userNameToNew;
UpdateModel(RM);
this.repository.AddRightTransfer(RM);
}
return RedirectToAction("RightTransfer");
My faulty model code is given below:
public void AddRightTransfer(Right_Matrix RM)
{
context.AddObject("Right_Matrix", RM);
context.SaveChanges();
}
My code shows error once it is in the model code stating the DataReader is already open and I need to close it first.
Please suggest a workaround.

Answer 1

Try moving the AddRightTransfer loop out of the LINQ foreach, and into a separate one. I think LINQ is executing the first add before the database result set is closed. By moving the call to AddRightTransfer into a second foreach, you should avoid the problem, if that's what is happening.
Here's an example:
List<Right_Matrix> matrixes = new List<Right_Matrix>();
foreach (var Data in rMatrix)
{
Right_Matrix rm = new Right_Matrix();
rm.Column_Id = Data.Column_Id;
rm.ProMonSys_Right = Data.ProMonSys_Right;
rm.UserName = userNameToNew;
UpdateModel(rm);
matrixes.Add(rm);
}
foreach (var rm in matrixes)
{
this.repository.AddRightTransfer(rm);
}

Answer 2

The problem is that you are modifying the database while still iterating over it. Either finish the query before modifying, like this:
foreach(var Data in rMatrix.ToArray())
Or don't modify the database in your loop, like this:
foreach(var Data in rMatrix)
{
RM.Column_Id = Data.Column_Id;
RM.ProMonSys_Right = Data.ProMonSys_Right;
RM.UserName = userNameToNew;
UpdateModel(RM);
context.AddObject("Right_Matrix", RM);
}
context.SaveChanges();
Obviously, those two context. calls would have to be made into methods on your repository, but you get the picture.