Question

I insert a new object into LINQ-to-SQL DataContext without calling SubmitChanges() yet:

MyDataContext db = new MyDataContext();
MyObject newObject = new MyObject() 
{
   Id = 1,
   Name = "MyName"
};
db.MyObjects.InsertOnSubmit(newObject);

Now in another place in my code I want to retrieve this new object, even though it is not in the database yet. So I pass the same DataContext instance there, because I believe that the new object is cached inside it. And now I want to retrieve it. But this doesn’t work:

MyObject newObject = db.MyObjects.Where(o => o.Id == 1).SingleOrDefault();

How can I do what I want? Is that possible?

Answer 1

Try:

db.MyObjects.SingleOrDefault(o => o.Id == 1);

You’d think this would be the same, but see these two connect issues:

• LINQ-to-SQL doesn’t use cache for lookup
• LINQ-to-SQL still roundtrips for ID lookups (3.5SP1)

If that doesn’t work, I know that the .Single(o => o.Id == 1) works in 3.5 SP1 (I don’t know if I tried .SingleOrDefault(pred)). Apparently the .Where(o => o.Id == 1).Single() is fixed in 4.0 – again, I haven’t tried .Where(pred).SingleOrDefault().