handler.Original has same values as handler.Entity in GlobalUpdating.

[falkartis]

I've created a method using this library to control update operations that looks like this:

Triggers<Entity, DbContext>.GlobalUpdating.Add(handler => {
	if (!ChangeAllowed(handler.Original, handler.Entity)) {
		handler.Cancel = true;
	}
});

The problem I get is that both handler.Original and handler.Entity have the new values and my ChangeAllowed method always returns true.

This happens only when I'm passing a new Entity to the Update method from DbSet.
It doesn't happen if I modify a entity queried from the DbSet and then call the Update method.

[NickStrupat]

This is because new entities don't have "original values". The concept of original values is for entities that have already been persisted.

[falkartis]

I understand that Original refers to the in-memory "original" entity rather than the entity that's in the database in the moment of the transaction.
My issue here is that it represents a security concern if a handler accepts a update because it hasn't been able to detect the changes correctly.
I can write a workaround and retrieve the database real original entity to use that as input of the validation method, but doing so will consume a lot of time. In this case there should be a way to tell the two situations apart.

[falkartis]

So I rephrase the question:

How to detect if a entity has been retrieved from a DbSet and modified or if it has been created in some other way?

[NickStrupat]

If the entity is new, the Insert... triggers will be raised. If it existed already, the Update... triggers will be raised.

[falkartis]

Let's consider following scenario:
Our database has a Users table like this one:

 ID  |  Name
-------------
 1   |  Foo
 2   |  Bar

And the code looks like this:

var dbCtx = SomeDatabaseInstantiationMechanism();
var user = new User { ID = 2, Name = "Baz" };
dbCtx.Users.Update(user);
dbCtx.SaveChanges();

In this case the GlobalUpdating triggers will be called and both handler.Original and handler.Entity will have "Baz" in the Name field.