Tip 19 – How to use Optimistic Concurrency with the Entity Framework

re: Tip 19 – How to use Optimistic Concurrency with the Entity Framework

Alex D James — Fri, 09 Mar 2012 17:29:02 GMT

Paul... yeah good question.

I'm often guilty of that particular sin - thanks for pointing it out!

re: Tip 19 – How to use Optimistic Concurrency with the Entity Framework

Paul Schirf — Tue, 28 Feb 2012 18:27:05 GMT

Why use a class named Post in an example, when it could confuse people thinking that it has some meaning?

re: Tip 19 – How to use Optimistic Concurrency with the Entity Framework

Michael Baarz, tecbehind.de — Mon, 09 May 2011 12:22:17 GMT

Hey,

until now with the actual version of entityframework it says to me that its not possible to set "Computed" for timestamp and rowversion rows. So i cant get it rid by updating the LastChanged (my ConcurrencyCheck) automatically. Whats the workaround for that? When i set LastChanged before saving i get the ConcurrencyException (normal) but when i cant set it to Computed what to do to get it rid? Help me please!

re: Tip 19 – How to use Optimistic Concurrency with the Entity Framework

sweYoda — Sun, 30 Jan 2011 00:49:01 GMT

I had a problem where I created a 'standard' table with a 'standard' attribute that is of type DateTime and when I created an object of that table and created a new DateTime object and added it to the right parameter of that table-object it contained milliseconds, but that was in conflict to the databasetype. So I had to create a DateTime object without miliseconds.

//This code failed:

Order order = new Order();

DateTime dt = DateTime.Now;

order.timeOrdered = dt;

db.AddToOrders(order);

db.SaveChanges(); // OptimisticConcurrencyException

//This worked:

Order order = new Order();

DateTime dt = new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, DateTime.Now.Hour, DateTime.Now.Minute, DateTime.Now.Second);

order.timeOrdered = dt;

db.AddToOrder(order);

db.SaveChanges();

re: Tip 19 – How to use Optimistic Concurrency with the Entity Framework

Hugh — Thu, 17 Jun 2010 22:13:46 GMT

Please help, I have a real problem with Concurrency in EF4.

I have 3 database tables: User, Session, and Workstation.

I am using Concurrency mode = Fixed and StoreGeneratedPattern=Computed on timestamp columns in Workstation and User, but not Session.

I create a new Session object. It has relationships to User and Workstation objects. I just set those relationship navigation properties directly to existing objects I already had selected from the Context before.

Next I save the Session object by calling Context.SaveChanges(). When I use SQL Profiler to look at the SQL, it always updates all 3 objects. But I only want it to save the Session. It is re-saving the Workstation and the User objects (just touching the Timestamp and selecting it back) because they have the Fixed Concurrency Timestamp fields and they participate in a relationship with the new Session.

This is a performance concern when using EF4, since I am only changing one object I just want to save one object to the database. How can I prevent EF4 from also saving the related objects when I have Concurrency mode=Fixed and StoreGeneratedPattern=Computed on timestamp columns in those related tables?

Thanks for your help,

Hugh

re: Tip 19 – How to use Optimistic Concurrency with the Entity Framework

Alex D James — Fri, 09 Oct 2009 05:54:43 GMT

@Renato and Iván

Hmm I'm not sure what the limitation is with Model First, but what you need in the SSDL is a timestamp column for SQL server.

Hope this helps

Alex

re: Tip 19 – How to use Optimistic Concurrency with the Entity Framework

Iván — Thu, 08 Oct 2009 19:25:38 GMT

Tried it but as soon as I want to 'generate database script from model', I get the 'The given key was not present in the dictionary' error.

Would you please tell us what the equivalent settings in the database column version is for:

'ConcurrencyMode = Fixed'

'StoreGeneratedPattern = Computed'

That way I can try to create the table first and them update the model.

I have the same problem. I need help, please

re: Tip 19 – How to use Optimistic Concurrency with the Entity Framework

Renato — Tue, 09 Jun 2009 04:45:06 GMT

Tried it but as soon as I want to 'generate database script from model', I get the 'The given key was not present in the dictionary' error.

Would you please tell us what the equivalent settings in the database column version is for:

'ConcurrencyMode = Fixed'

'StoreGeneratedPattern = Computed'

That way I can try to create the table first and them update the model.

Meta-Me : Entity Framework Tips

Meta-Me : Entity Framework Tips — Mon, 08 Jun 2009 21:44:51 GMT

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