How to enable concurrency checking using EF 5.0 Code First?
c#, entity-framework-5, optimistic-concurrency
Solution
You can use ConcurrencyCheck annotation on a property ( http://msdn.microsoft.com/en-us/data/gg193958.aspx ) or IsConcurrencyToken() or .IsRowversion when configuring a property with fluent API ( http://msdn.microsoft.com/en-us/data/jj591617#1.12). Typically you would have a rowversion column in the database.
Problem
I would like to do a check-then-update in an atomic operation. I am using dbcontext to manage the transaction. I was expecting to get an exception if the record has been modified by another thread but no exception is thrown. Any help would be appreciated. Here's my output: ``` Thread-4: Reading... Thread-5: Reading... Thread-5: Updating destination 1 Thread-4: Updating destination 1 Thread-4: SaveChanges Thread-5: SaveChanges ``` Here's my code snippet: ``` public static void Main(string[] args) { PopulateData(); (new Thread(UpdateDestination1)).Start(); (new Thread(UpdateDestination1)).Start(); } public static void UpdateDestination1() { using (var context1 = new BreakAwayContext()) { Console.WriteLine("Thread-{0}: Reading...", Thread.CurrentThread.ManagedThreadId); var d = context1.Destinations.FirstOrDefault(); Console.WriteLine("Thread-{0}: Updating destination {1}", Thread.CurrentThread.ManagedThreadId, d.DestinationId); d.Name = "Thread-" + Thread.CurrentThread.ManagedThreadId; try { context1.SaveChanges(); Console.WriteLine("Thread-{0}: SaveChanges", Thread.CurrentThread.ManagedThreadId); } catch (OptimisticConcurrencyException) { Console.WriteLine("OptimisticConcurrencyException!!!"); throw; } } } ```