I have a "invoice" business object (ultimately inherits from the BusinessObjectLinq class). I have some code which adds/updates/deletes line items and saves the results. Then I create a new instance of invoice so I can do some tests on what just occurred (when I kept the existing instances Linq to Sql was trying to be helpful and kept returning a cached copy of the data). The code does the following:

var invoice = new InvoiceBizObj();
invoice.Load(pk);
invoice.UpdateStatus();

// InvoiceBizObj class
public void UpdateStatus()
{
   this.UpdateStatus(this.Entity);
}

public void UpdateStatus()
{
   var count = entity.InvoiceLines.Count();
   var valid = this.Validate(entity);

   if (count > 0 && valid && entity.InvoiceStatus.Code == "IN")
   {
      entity.InvoiceStatus = this.Context.InvoiceStatus.Single(s => s.Code == "OP");
      this.Save(entity);
   }
}

The problem I'm running into is that Save() is failing with a "An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported.". I originally tried just setting the foreign key directly, but it didn't like that. It failed with a "operation is not valid due to the current state of the object" error, which is why I replaced it with the .Single() call.

Thinking that maybe the entity.InvoiceLines.Count() was causing the problem I tested it by hardcoding the count to 1. Same error. I removed the check for entity.InvoiceStatus.Code in the "if" statement. Same error.

I know each business object creates its own DataContext but in this case I'm only dealing with one of them.

Anyone see what I'm missing?

-Paul