Question

I have an MVC3 View that’s posting back a set of input values via Ajax to my controller. My controller is then creating a new FieldTripRoute object on my context and attempting to insert it into the database.

I just can’t figure out what’s going on. I’ve triple checked my Designer schema and my DB schema and they match perfectly. So it can’t be the normal issue of a column not existing or being nullable in one area but not another. However, I keep receiving a “Row Not Found or Changed” exception every time I attempt to submit changes.

The stack trace on the exception looks like this:

   at System.Data.Linq.ChangeProcessor.SubmitChanges(ConflictMode failureMode)
   at System.Data.Linq.DataContext.SubmitChanges(ConflictMode failureMode)
   at System.Data.Linq.DataContext.SubmitChanges()
   at ManageMAT.Controllers.FieldTripController.RouteAdd(Int32 id, FormCollection collection) 

This is the code that’s being called to add the new Route object from the Controller:

        [HttpPost]
        public ActionResult RouteAdd(int id, FormCollection collection)
        {
            FieldTrip trip = context.FieldTrips.Single(ft => ft.ID == id);

            if (trip == null) return Json(new { success = false, message = "Field trip not found." }); ;

            try
            {

                FieldTripRoute tripRoute = new FieldTripRoute();

                tripRoute.FieldTripID = trip.ID;                
                tripRoute.Date = DateTime.Parse(collection["Date"]);
                tripRoute.ArrivalTime = DateTime.Parse(collection["ArrivalTime"] + " " + DateTime.Now.ToShortDateString());
                tripRoute.DepartureTime = DateTime.Parse(collection["DepartureTime"] + " " + DateTime.Now.ToShortDateString());
                tripRoute.Destination = collection["Destination"];
                tripRoute.PickupLocation = collection["PickupLocation"];
                tripRoute.RouteID = Convert.ToInt32(collection["RouteID"]);           

                context.FieldTripRoutes.InsertOnSubmit(tripRoute);
                context.SubmitChanges();

                return Json(new { success = true, message = "Success!" });
            }
            catch (Exception ex)
            {
                return Json(new { success = false, message = ex.Message });
            }
        }

And here is my Designer and DB Table Columns:

I’ve also attempted to view the SQL this is outputting in both the logging available on the context object and in SQL Profiler, but it seems to be failing before it’s even hitting the Database server.

Edit: Forgot to add one other thing, when I’m initially creating the new FieldTripRoute object at the beginning of the Add action I noticed that it’s not retrieving the correct ID from the database identity series. Perhaps this is related?

I’ve also tried setting the Update Check on every field in the designer to Never just to see if it was some kind of bizarre concurrency collision going on, but I am still receiving the same error.

I’m really at a loss for what could be causing this issue. Any ideas are appreciated.

Answer 1

This message is thrown every time the row is not inserted for whatever reason. For DML statements Linq to SQL checks the number of modified rows. SQL Server returns this count. It is checked to be one.

The big question is why is the count zero and yet no error message is being sent by SQL Server. Start SQL Server profiler and post the SQL that L2S generates. Run the SQL manually and see what happens. Does a row get inserted? Does its identity value get returned?

Edit: More debugging ahead: Shut down SQL server just before you to the SubmitChanges to make sure that the database is not being hit. Lets make sure to cut this branch off the search tree.

Next, step into the Linq to SQL source code to see whats up. If you have R# this is easy: Press ctrl-shift-t, search ChangeProcessor, click and navigate to the “sources from symbol files”. Find the function SubmitChanges and put a breakpoint in there. If you don’t have R#, you need to dig out some tutorial on the web for this (it’s going to take about 5min).

Step through the source to find why the exception is thrown.