ASP.NET MVC LINQ-2-SQL as model - how to update? - linq-to-sql

Question

Is it possible to use LINQ2SQL as MVC model and bind? - Since L2S "attachement" problems are really showstopping.
[HttpPost]
public ActionResult Save(ItemCart edCart)
{
using (DataContext DB = new DataContext())
{
DB.Carts.Attach(edCart);
DB.Carts.Context.Refresh(RefreshMode.KeepChanges, edCart);
DB.Carts.Context.SubmitChanges();
DB.SubmitChanges();
}
return RedirectToAction("Index");
}
That does not work. :S

Answer 1

What does your Save View look like?
You can't just attach a new item to the EntitySet like that. -> Attaching requires a lot of checks and it is a real pain to implement. I tried it myself and didn't like it at all.
In your [HttpPost] method you'll need to update the model before you can save it:
[HttpPost]
public ActionResult Save(int id, ItemCart edCart) {
DataContext DB = new DataContext(); // I'm doing this without a using keyword for cleanliness
var originalCart = DB.Carts.SingleOrDefault(c => c.ID == id); // First you need to get the old database entry
if (ModelState.IsValid & TryUpdateModel(edCart, "Cart")) { // This is where the magic happens.
// Save New Instance
DB.SubmitChanges.
return RedirectToAction("Details", new { id = originalCart.ID });
} else {
// Invalid - redisplay with errors
return View(edCart);
}
}
It tries to update the model from the controllers valueprovider using they "Cart" prefix.