ADO.NET实体模型更新

Question

Hi i am trying to update a record from the database, but for some reason the record is not updated. I am using ADO.NET entity Framework 4.0

public void updateCredits(string username)
 {
     myDBEntities Entity = new myDBEntities();
     User u = Entity.Users.SingleOrDefault(u => u.username == username)
     u.firstname = "name";
     u.credits = 11.5;
     Entity.SaveChanges();
 }

I tried restarting VS and even the SQL Server but no luck. Am i doing something wrong?

Answer 1

It looks like there is an issue with change tracking. You can try manually marking the User entity as changed like so:

public void updateCredits(string username)
 {
     myDBEntities Entity = new myDBEntities();
     User u = Entity.Users.SingleOrDefault(u => u.username == username)
     u.firstname = "name";
     u.credits = 11.5;
     Entity.Entry(u).State = EntityState.Modified;  //<-- manually indicate the entity was changed
     Entity.SaveChanges();
 }

If the above code works, then there's a good chance ChangeTracking is being disabled somehow.