Question

In the below code I am updating IndexOrder by Id using TryUpdateModel. Below update hit DB 2 times. Once retrieving current record by Id than updating single row.

I am using LINQ To EF

 foreach (var i in indexArraay)
            {
                SubMenu existingMenu = _menu.SubSingle(Int32.Parse(i.id.ToString()));
                existingMenu.IndexOrder = string.IsNullOrEmpty(i.index.ToString()) ? 0 : Int32.Parse(i.index.ToString());
                TryUpdateModel(existingMenu);
                _menu.Add();
            }

In SQL we don’t do that like in below statement.

UPDATE table_name
SET column1=value, column2=value2,...
WHERE some_column=some_value

Am I wrong somewhere or Is there any better way to write LINQ update expression?

I am not talking about performance here.

Answer 1

In LINQ-to-SQL you can use Attach for this. The code below will update Order value for exisitin menu item with id 1.

int myId = 1;
int newOrder = 10;

using (var dataContext = new DataContext("..."))
{
    var table = dataContext.GetTable(typeof(Type));
    var menuItem = new MenuItem { Id = myId };
    table.Attach(menuItem);
    menuItem.Order = newOrder;
    dataContext.SubmitChanges();
}

[Edit]

For LINQ-to-Entities take a look at Attaching and Detaching Objects.

The analog is ObjectSet.Attach Method.