Den 27. okt. 2010 kl. 04.21 skrev Rickard Öberg: > On 2010-10-26 22.11, Ronnie Nessa wrote: >> 1. Is using unitOfWork.create(MyEntity.class, "myReadableIdentifier") a >> good solution to support my use case? > > Yes, and I do the exact same thing: on startup I check whether some bootstrap > entities are available (in EventSourcing all events have to come from > entities, so bootstrapping the first one is mandatory), and if not I use the > uow.newEntity(MyEntity.class,SOMECONSTANTID) method. > > In fact, I ALWAYS use the newEntity(class,id) method, since entities are > always created as a response to an event, and the event MUST have the id of > the new entity. Otherwise replay of events wouldn't create the same state.
Great, then I know that I´m on the right track:) > >> 2. Is there an easy way to change the identity of an entity that already >> exist in the EntityStore? > > Not really, no. You can always create a copy of it and store it, but the > references to it is the main issue. I have a few usecases of "replace A with > B" and "merge A into B" and what I do is to basically query for all known > references to A and set them to B in code. Yes, it´s the references i figured was the hard part as well. Maybe that is what I have to do combined with the Service as you pointed out under. > >> 3. How do you use the MigrationOperation to update entities when you >> don´t know the id of the entities until runtime? Specifically; How do >> you get access to application components from an instance of a >> MigrationOperation? > > Migration is run before the application is really started, in a sense, so > you're only allowed to work on state. If you need anything else, then I > recommend doing a service with .instantiateOnStartup(), and implement the > more complex logic in the activate() method. > > /Rickard That might be the way to go. Thanks. Best regards Webstep AS RONNIE NESSA | Senior Consultant Mob : +47 970 69 512 | [email protected] www.webstep.no _______________________________________________ qi4j-dev mailing list [email protected] http://lists.ops4j.org/mailman/listinfo/qi4j-dev
