with Salve you can do it like this:
UserBalance User.getBalance() {
return accountingService.getBalance (user);
}
because your User domain object would have access to accountingService.
see http://salve.googlecode.com
-igor
On 10/9/07, Joe Toth <[EMAIL PROTECTED]> wrote:
> This is a Hibernate question, but Eelco's 'class reloading' post
> reminded me to ask on this list. I asked in the Hibernate forums, but
> received no responses. Maybe someone here has a similar problem or some
> thoughts/ideas.
>
> * The Problem
>
> Ok, so you have IoC where you inject services you want to use in other
> services. Well basically I want to do something similar with my domain
> model.
>
> I have 3 different maven modules. (I have a lot more, but for
> simplicity's sake)
> 1. user-module - Which contains a User.class with fields like
> emailAddress, password, address information, etc.
> 2. accounting-module - which depends on user-module and need to keep
> track of a user's pending account balance, posted balance, etc
> 3. mywebapp-module - which depends on accounting-module
>
> Currently
> If I want to get a user's account balance I have to
> User user = userService.getUser("id");
> UserBalance bal = accountingService.getBalance (user);
>
> It gets very cumbersome trying to write a ton of different queries to
> retrieve data from the different tables. For instance if I want to get
> someone's account balance via their e-mail address a query exists in the
> userService.findByEmailAddress(), but I have to write another method in
> the accountingService to do this again.
>
> * What Hibernate offers
>
> 1. Hibernate offers dynamic mode where you can persist fields via a
> Map, but you have to set the mode on a 'per session' basis.
> a. This solution could work if you could have POJO and DYNAMIC-MAP
> in the same session. (which I don't see why this wouldn't be possible)
> 2. Hibernate offers dynamic components, but User.class has to know
> about the dynamic components and they cannot be dynamically wired up.
>
> * What I've been working on
>
> Modules contributing fields to models of other modules.
> Instead of UserBalance becoming its own class its now an interace that
> 'contributes' its fields (via getters/setters) to the User.class so I
> can do this.
> User user = userService.findByEmailAddress("[EMAIL PROTECTED]");
> UserBalance balance = (UserBalance) user;
>
> The only way I can think of to accomplish this is by creating new
> classes via javassist/cglib.
>
> 1. I take User.class and see if there are any interfaces that want to
> contribute their fields to User.class
> 2. I create a new class that extends User.class with the new fields,
> User$Enhanced.class
> 3. Then for each class with a field User.class I replace it with the
> newly generated class
>
> There is one big downfall to this approach. You can't create classes via
> the new operator.
> User user = new User();
> UserBalance balance = (UserBalance) user; <-- User does not implement
> UserBalance, throwsClassCastException.
> balance.setPending(0.0);
> session.save(user); <-- Hibernate does not know about a User entity,
> only the new User$Enhanced.class!
>
> You have to create objects via a factory so the object is actually of
> type User$Enhanced
> User user = factory.create(User.class);
>
> This is where class reloading would come in handy!
>
> * Conclusion
> I have not finished a prototype of this yet as there is a big learning
> curve of (byte code engineering) playing with javassist.
> I spent a whole day playing with this when I have other priorities, but
> this could speed up development immensely.
>
> Whoever read this, can you give me some feedback?
> Think its a good idea?
> Think a slippery slope of problems will unfurl once I get a prototype
> running?
> Are there any other existing solutions?
>
>
> Thanks everyone!
>
>
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