Comments on: ActiveObjects 0.8 Released

By: Francisco Valdez

Francisco Valdez — Mon, 19 Apr 2010 16:28:51 +0000

Is there any way to auto-generate classes from a .SQL file? I have a big system, and I have all my DB generated and working. If I want to migrate to ActiveObjects, I will need something that generates the classes from a .SQL file, so I don’t have to write all manually.

By: Alex Zuzin

Alex Zuzin — Fri, 09 Oct 2009 23:53:37 +0000

Awesome stuff, after years of Hibernate/EJB3 torture.
Any chance the distribution can move off the infinitely godawfuly unreliable dev.java.net?
Right now I can’t even download the release.
Google Code, perhaps?

By: Mark Wilhelm

Mark Wilhelm — Tue, 26 May 2009 23:06:23 +0000

Any update on the 0.9 or 1.0 release? And is Oracle “done” too? This looks very promising and appreciate all the hard work.

By: Daniel Spiewak

Daniel Spiewak — Wed, 16 Jul 2008 16:03:09 +0000

Technically, there is a forum on the java.net project page, but nobody really uses it. I monitor it and certainly would not mind if it were used more, but currently the best place to discuss AO is on the users list (users [at] activeobjects.dev.java.net)

By: Thomas Trocha

Thomas Trocha — Wed, 16 Jul 2008 13:58:09 +0000

Is there somewhere a discussion-forum concerning activeobjects?

By: Daniel Spiewak

Daniel Spiewak — Mon, 14 Jul 2008 17:43:00 +0000

I’m not sure what you mean by “aggregations”. Can you send me (or even better, the ActiveObjects users’s list) an email directly and explain in more detail?

By: Stephan Schwab

Stephan Schwab — Tue, 08 Jul 2008 01:05:56 +0000

Is @Preload({“emitter”, “avg(processingTime) as processingTime” }) together with entityManager.find(AverageProcessingTimesByEmitter.class, Query.select().group(“emitter”)) the right way to do aggregations with AO? It works but I’m a bit unsure whether it’s supposed to work that way. Any thoughts, suggestions?

By: Daniel Spiewak

Daniel Spiewak — Wed, 09 Apr 2008 03:39:54 +0000

Glad you like it! If you have any suggestions, please don’t hesitate to send them my way.

With regards to migrate, I wanted to do it so that it just migrated all of the entities in scope, but unfortunately Java doesn’t provide a way to do this reflectively. What I *can* do is migrate all dependent entities. So if you consider your schema as a directed graph, with paths defined by foreign key relationships, it is only necessary to add the unconnected “roots” of the graph and the rest will follow. So if Person has a getter which returns a Company, you can migrate Person and ActiveObjects will automatically traverse the dependencies and migrate Company as well. It’s not a perfect solution, but it does save listing *all* of the entities in the migration.

By: realgt

realgt — Wed, 09 Apr 2008 01:15:55 +0000

hey thanks for the reply – that makes sense i guess, although it’d be easier to call EntityManager#migrate without a long list of classes and have it automatically migrate all classes which extend Entity. i guess i can’t see a use case where you don’t pass it a list of all your classes (which could get rather troublesome) …especially since it drops all unlisted class tables.

in any case, i looked around and found AO to be the most developed ActiveRecords port to java, great job. looking forward to future releases.

By: Daniel Spiewak

Daniel Spiewak — Tue, 08 Apr 2008 01:24:26 +0000

You’re always welcome to send me an email directly, or (even better) email the users list (users@activeobjects.dev.java.net).

To answer your question, ActiveObjects migrations literally sync the database schema with your entity structure. The *entire* database is made to sync, which means that if any tables are there which shouldn’t be, they are removed. It’s like making a commit into an SCM. The remote state is made to match your local state, including any files you may have deleted.

There’s a feature scheduled for 2.0 which will allow configurability in this area, but for right now migrations are a true sync, regardless of what data may be lost.