Linq Update to SQL

Question

All was running along fine till I tried a simple SQL Server update from Linq. My code is:

DataClasses1DataContext db = new DataClasses1DataContext("mySQLServer");
        db.Connection.ConnectionString = ConfigurationManager.ConnectionStrings["mySQLServer"].ToString();

        var results = (from bl in db.a_Bellows_Lots
                       where bl.Job == this.theJob
                       where bl.BellowsLot == this.theLot
                       select bl).SingleOrDefault();

        results.Quantity = this.theQuantity;
        try
        {
            db.SubmitChanges();
        }
        catch (Exception ex)
        {
            error += " " + ex.Message;

But the value is not getting changed. I modeled this in LinqPad with this;

string JobNumber = "A2559038A";
string LotNumber = "17213A";

var results = (from bl in a_Bellows_Lots
             where bl.Job == JobNumber
             where bl.BellowsLot == LotNumber
             select new 
             {
                bl.Quantity
             }).SingleOrDefault();

results.Quantity = 1;

this.SubmitChanges();

This gives me a design time error of "Propery or indexer 'AnonymousType#1.Quantity' cannot be assigned to -- it is read only."

I've used this design model before and it works:

            DataClasses1DataContext db = new DataClasses1DataContext("mySQLServer");
        db.Connection.ConnectionString = ConfigurationManager.ConnectionStrings["mySQLServer"].ToString();

        var results = (from x in db.a_Cleaning_Logs
                       where x.CleaningLogID == CleaningLogID
                       select x).SingleOrDefault();

        results.EndTime = EndDate;
        results.EmployeeOut = employeeOut;
        results.CleaningDone = cleaningDone;
        db.SubmitChanges();

What is the difference; what am I doing wrong?

Answer 1

Anonymous objects are read-only.

So the following should work

var results = (from bl in a_Bellows_Lots
         where bl.Job == JobNumber
         where bl.BellowsLot == LotNumber
         select bl).SingleOrDefault();

 results.Quantity = 1;

 this.SubmitChanges();

but not if you use new { bl.Quantity} instead of returning the whole record.

If the former does not work, then perhaps your table does not have an identity column.

If you are using LinqPad, you can call this.GetChangeSet().Dump(); before you submit the changes to see if there are any changes.