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Posted to users@wicket.apache.org by Joe Toth <jo...@gmail.com> on 2007/10/09 23:28:47 UTC
Dynamic Entity Classes
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("my@email.com");
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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Re: Dynamic Entity Classes
Posted by Joe Toth <jo...@gmail.com>.
Salve is interesting...
One problem, user-module does not know about accounting-module.
On Wed, 2007-10-10 at 00:30 +0200, Gerolf Seitz wrote:
> heh, i knew this would come up ;)
>
> On 10/10/07, Igor Vaynberg <ig...@gmail.com> wrote:
> >
> > 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 <jo...@gmail.com> 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("my@email.com");
> > > 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!
> > >
> > >
> > > ---------------------------------------------------------------------
> > > To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> > > For additional commands, e-mail: users-help@wicket.apache.org
> > >
> > >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> > For additional commands, e-mail: users-help@wicket.apache.org
> >
> >
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
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Re: Dynamic Entity Classes
Posted by Gerolf Seitz <ge...@gmail.com>.
heh, i knew this would come up ;)
On 10/10/07, Igor Vaynberg <ig...@gmail.com> wrote:
>
> 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 <jo...@gmail.com> 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("my@email.com");
> > 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!
> >
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> > For additional commands, e-mail: users-help@wicket.apache.org
> >
> >
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> For additional commands, e-mail: users-help@wicket.apache.org
>
>
Re: Dynamic Entity Classes
Posted by Igor Vaynberg <ig...@gmail.com>.
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 <jo...@gmail.com> 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("my@email.com");
> 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!
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> For additional commands, e-mail: users-help@wicket.apache.org
>
>
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
For additional commands, e-mail: users-help@wicket.apache.org