Re: Using composition instead of inheritance
You'll have to dig into what that NPE is exactly. Hard to diagnose without that.
Sent from my iPhone
On Jun 2, 2012, at 1:52 AM, Paul Hoadley pa...@logicsquad.net wrote:
Hi Mike,
On 01/06/2012, at 10:54 PM, Mike Schrag wrote:
I'm a little concerned about inverse relationships to FrameworkPerson when
you toss it this might require more surgery than this.
This is what I'm doing:
@Override
public void didFinishLaunching() {
super.didFinishLaunching();
EOModel fmkModel =
EOModelGroup.defaultGroup().modelNamed(Auth);
EOModel appModel =
EOModelGroup.defaultGroup().modelNamed(Survey);
EOEntity fmkEntity = fmkModel.entityNamed(Organisation);
fmkModel.removeEntity(fmkEntity);
EOEntity appEntity = appModel.entityNamed(SSOrganisation);
appEntity.setName(Organisation);
return;
}
It looked like it might be working until I threw that into a D2W front-end
with the same models and database. Just after login, as it builds the
ERMODQueryEntitiesPage, I get this:
NullPointerException
at
com.webobjects.eoaccess.EODatabase.addModelIfCompatible(EODatabase.java:575)
... skipped 15 stack elements
at
com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecification(EOObjectStoreCoordinator.java:488)
at
com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4069)
at er.extensions.eof.ERXEC.objectsWithFetchSpecification(ERXEC.java:1215)
at
com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:)
at
net.logicsquad.webobjects.auth.model.auth._Person.fetchPersons(_Person.java:442)
at
net.logicsquad.webobjects.auth.model.auth._Person.fetchAllPersons(_Person.java:436)
at
net.logicsquad.webobjects.auth.model.auth._Person.fetchAllPersons(_Person.java:432)
at
net.logicsquad.survstar.DirectAction.canUseBootstrapCredentials(DirectAction.java:108)
at net.logicsquad.survstar.DirectAction.loginAction(DirectAction.java:143)
... skipped 4 stack elements
at
com.webobjects.appserver.WODirectAction.performActionNamed(WODirectAction.java:144)
at
er.extensions.appserver.ERXDirectAction.performActionNamed(ERXDirectAction.java:401)
at
er.directtoweb.ERD2WDirectAction.performActionNamed(ERD2WDirectAction.java:463)
... skipped 9 stack elements
Any thoughts on the appropriate additional surgery?
--
Paul Hoadley
http://logicsquad.net/
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Re: Using composition instead of inheritance
On 02/06/2012, at 11:11 PM, Mike Schrag wrote: You'll have to dig into what that NPE is exactly. Hard to diagnose without that. Here's the full stack trace. java.lang.NullPointerException at com.webobjects.eoaccess.EODatabase.addModelIfCompatible(EODatabase.java:575) at com.webobjects.eoaccess.EODatabaseContext.registeredDatabaseContextForModel(EODatabaseContext.java:1003) at com.webobjects.eoaccess.EODatabaseContext.registeredDatabaseContextForModel(EODatabaseContext.java:1033) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.webobjects.foundation.NSSelector.invoke(NSSelector.java:358) at com.webobjects.foundation.NSSelector._safeInvokeSelector(NSSelector.java:110) at com.webobjects.eoaccess.EODatabaseChannel.setEntity(EODatabaseChannel.java:131) at com.webobjects.eoaccess.EODatabaseChannel.setCurrentEntity(EODatabaseChannel.java:160) at com.webobjects.eoaccess.EODatabaseChannel._setCurrentEntityAndRelationshipWithFetchSpecification(EODatabaseChannel.java:740) at com.webobjects.eoaccess.EODatabaseChannel._selectWithFetchSpecificationEditingContext(EODatabaseChannel.java:808) at com.webobjects.eoaccess.EODatabaseChannel.selectObjectsWithFetchSpecification(EODatabaseChannel.java:234) at com.webobjects.eoaccess.EODatabaseContext._objectsWithFetchSpecificationEditingContext(EODatabaseContext.java:3055) at com.webobjects.eoaccess.EODatabaseContext.objectsWithFetchSpecification(EODatabaseContext.java:3195) at com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecification(EOObjectStoreCoordinator.java:488) at com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4069) at er.extensions.eof.ERXEC.objectsWithFetchSpecification(ERXEC.java:1215) at com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:) at net.logicsquad.webobjects.auth.model.auth._Person.fetchPersons(_Person.java:442) at net.logicsquad.webobjects.auth.model.auth._Person.fetchAllPersons(_Person.java:436) at net.logicsquad.webobjects.auth.model.auth._Person.fetchAllPersons(_Person.java:432) at net.logicsquad.survstar.DirectAction.canUseBootstrapCredentials(DirectAction.java:109) at net.logicsquad.survstar.DirectAction.loginAction(DirectAction.java:150) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.webobjects.appserver.WODirectAction.performActionNamed(WODirectAction.java:144) at er.extensions.appserver.ERXDirectAction.performActionNamed(ERXDirectAction.java:401) at er.directtoweb.ERD2WDirectAction.performActionNamed(ERD2WDirectAction.java:463) at com.webobjects.appserver._private.WOActionRequestHandler._handleRequest(WOActionRequestHandler.java:259) at com.webobjects.appserver._private.WOActionRequestHandler.handleRequest(WOActionRequestHandler.java:161) at er.extensions.appserver.ERXDirectActionRequestHandler.handleRequest(ERXDirectActionRequestHandler.java:126) at com.webobjects.appserver.WOApplication.dispatchRequest(WOApplication.java:1687) at er.extensions.appserver.ERXApplication.dispatchRequestImmediately(ERXApplication.java:2029) at er.extensions.appserver.ERXApplication.dispatchRequest(ERXApplication.java:1994) at com.webobjects.appserver._private.WOWorkerThread.runOnce(WOWorkerThread.java:144) at com.webobjects.appserver._private.WOWorkerThread.run(WOWorkerThread.java:226) at java.lang.Thread.run(Thread.java:680) At DirectAction.loginAction(), there's a call to Person.fetchAllPersons(). Person is in the same framework model as Organisation, and it has a to-one relationship to Organisation. This is after I've removed the Organisation entity from the framework model and changed the name of the application entity to Organisation. Have I broken the framework model? -- Paul Hoadley http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
Not sure ... you might want to change the class name on your framework entity, and copy the attributes and relationships from the app entity into the framework entity (rather than delete entities). you'll have to debug what is busted .. just printing out all your entites, relationships, and their destination entities ... something will be null. you'll have to look into EODatabase to see what exactly is NPEing. On Jun 2, 2012, at 7:01 PM, Paul Hoadley pa...@logicsquad.net wrote: On 02/06/2012, at 11:11 PM, Mike Schrag wrote: You'll have to dig into what that NPE is exactly. Hard to diagnose without that. Here's the full stack trace. java.lang.NullPointerException at com.webobjects.eoaccess.EODatabase.addModelIfCompatible(EODatabase.java:575) at com.webobjects.eoaccess.EODatabaseContext.registeredDatabaseContextForModel(EODatabaseContext.java:1003) at com.webobjects.eoaccess.EODatabaseContext.registeredDatabaseContextForModel(EODatabaseContext.java:1033) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.webobjects.foundation.NSSelector.invoke(NSSelector.java:358) at com.webobjects.foundation.NSSelector._safeInvokeSelector(NSSelector.java:110) at com.webobjects.eoaccess.EODatabaseChannel.setEntity(EODatabaseChannel.java:131) at com.webobjects.eoaccess.EODatabaseChannel.setCurrentEntity(EODatabaseChannel.java:160) at com.webobjects.eoaccess.EODatabaseChannel._setCurrentEntityAndRelationshipWithFetchSpecification(EODatabaseChannel.java:740) at com.webobjects.eoaccess.EODatabaseChannel._selectWithFetchSpecificationEditingContext(EODatabaseChannel.java:808) at com.webobjects.eoaccess.EODatabaseChannel.selectObjectsWithFetchSpecification(EODatabaseChannel.java:234) at com.webobjects.eoaccess.EODatabaseContext._objectsWithFetchSpecificationEditingContext(EODatabaseContext.java:3055) at com.webobjects.eoaccess.EODatabaseContext.objectsWithFetchSpecification(EODatabaseContext.java:3195) at com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecification(EOObjectStoreCoordinator.java:488) at com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4069) at er.extensions.eof.ERXEC.objectsWithFetchSpecification(ERXEC.java:1215) at com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:) at net.logicsquad.webobjects.auth.model.auth._Person.fetchPersons(_Person.java:442) at net.logicsquad.webobjects.auth.model.auth._Person.fetchAllPersons(_Person.java:436) at net.logicsquad.webobjects.auth.model.auth._Person.fetchAllPersons(_Person.java:432) at net.logicsquad.survstar.DirectAction.canUseBootstrapCredentials(DirectAction.java:109) at net.logicsquad.survstar.DirectAction.loginAction(DirectAction.java:150) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.webobjects.appserver.WODirectAction.performActionNamed(WODirectAction.java:144) at er.extensions.appserver.ERXDirectAction.performActionNamed(ERXDirectAction.java:401) at er.directtoweb.ERD2WDirectAction.performActionNamed(ERD2WDirectAction.java:463) at com.webobjects.appserver._private.WOActionRequestHandler._handleRequest(WOActionRequestHandler.java:259) at com.webobjects.appserver._private.WOActionRequestHandler.handleRequest(WOActionRequestHandler.java:161) at er.extensions.appserver.ERXDirectActionRequestHandler.handleRequest(ERXDirectActionRequestHandler.java:126) at com.webobjects.appserver.WOApplication.dispatchRequest(WOApplication.java:1687) at er.extensions.appserver.ERXApplication.dispatchRequestImmediately(ERXApplication.java:2029) at er.extensions.appserver.ERXApplication.dispatchRequest(ERXApplication.java:1994) at com.webobjects.appserver._private.WOWorkerThread.runOnce(WOWorkerThread.java:144) at com.webobjects.appserver._private.WOWorkerThread.run(WOWorkerThread.java:226) at java.lang.Thread.run(Thread.java:680) At DirectAction.loginAction(), there's a call to Person.fetchAllPersons(). Person is in the same framework model as Organisation, and it has a to-one relationship to Organisation. This is after I've removed the Organisation entity from the framework model and changed the name of the application
Re: Using composition instead of inheritance
On 03/06/2012, at 8:59 AM, Mike Schrag wrote: Not sure ... you might want to change the class name on your framework entity, and copy the attributes and relationships from the app entity into the framework entity (rather than delete entities). This is looking promising. Changing the class name (without copying the additional attributes) allows me to display existing objects. Just quickly: is there an easy way to clone an EOAttribute from the application model entity for adding to the framework model entity? -- Paul Hoadley http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
Not . Sure ... Maybe can you spit out the plist of the orig and construct a new one with that plist? Sent from my iPad On Jun 2, 2012, at 8:09 PM, Paul Hoadley pa...@logicsquad.net wrote: On 03/06/2012, at 8:59 AM, Mike Schrag wrote: Not sure ... you might want to change the class name on your framework entity, and copy the attributes and relationships from the app entity into the framework entity (rather than delete entities). This is looking promising. Changing the class name (without copying the additional attributes) allows me to display existing objects. Just quickly: is there an easy way to clone an EOAttribute from the application model entity for adding to the framework model entity? -- Paul Hoadley http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
On 03/06/2012, at 12:02 PM, Mike Schrag wrote: Not . Sure ... Maybe can you spit out the plist of the orig and construct a new one with that plist? Thanks for the idea. I pressed on for a bit after creating the attribute manually, and it mostly looked good until saving a new object, at which point I hit a duplicate primary key issue, presumably because the framework entity was still using the sequence originally created for it rather than the sequence for the app entity... (I had already created an AppEntity directly in code at first startup, and now D2W was going to create an AppEntity that it thought was a FrameworkEntity.) I'm sure I could get there eventually, but it's starting to seem very complicated. I think I'll just revert to adding an attribute to the framework entity at runtime. -- Paul Hoadley http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
Hi Mike, On 30/05/2012, at 8:01 AM, Mike Schrag wrote: When your models load, replace FrameworkPerson entity with AppPerson entity, so fetches for FrameworkPerson are secretly the equivalent to what AppPerson fetches would be. Is this just a matter of calling removeEntity() and then addEntity() on the EOModel, or is there more that needs to be done? -- Paul Hoadley http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
On 01/06/2012, at 10:26 PM, Mike Schrag wrote: Remove FrameworkPerson entity, then rename AppPerson to be FrameworkPerson. Just model.removeEntity(frameworkPerson) and appPerson.setName(FrameworkPerson.ENTITY_NAME)? Thanks Mike. -- Paul. http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
... only one way to find out :) On Jun 1, 2012, at 9:13 AM, Paul Hoadley pa...@logicsquad.net wrote: On 01/06/2012, at 10:26 PM, Mike Schrag wrote: Remove FrameworkPerson entity, then rename AppPerson to be FrameworkPerson. Just model.removeEntity(frameworkPerson) and appPerson.setName(FrameworkPerson.ENTITY_NAME)? Thanks Mike. -- Paul. http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
I'm a little concerned about inverse relationships to FrameworkPerson when you toss it this might require more surgery than this. On Jun 1, 2012, at 9:13 AM, Paul Hoadley pa...@logicsquad.net wrote: On 01/06/2012, at 10:26 PM, Mike Schrag wrote: Remove FrameworkPerson entity, then rename AppPerson to be FrameworkPerson. Just model.removeEntity(frameworkPerson) and appPerson.setName(FrameworkPerson.ENTITY_NAME)? Thanks Mike. -- Paul. http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
On 01/06/2012, at 10:54 PM, Mike Schrag wrote: I'm a little concerned about inverse relationships to FrameworkPerson when you toss it this might require more surgery than this. I'll try it out over the weekend and see if anything explodes. -- Paul. http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
Hi Mike,
On 01/06/2012, at 10:54 PM, Mike Schrag wrote:
I'm a little concerned about inverse relationships to FrameworkPerson when
you toss it this might require more surgery than this.
This is what I'm doing:
@Override
public void didFinishLaunching() {
super.didFinishLaunching();
EOModel fmkModel =
EOModelGroup.defaultGroup().modelNamed(Auth);
EOModel appModel =
EOModelGroup.defaultGroup().modelNamed(Survey);
EOEntity fmkEntity = fmkModel.entityNamed(Organisation);
fmkModel.removeEntity(fmkEntity);
EOEntity appEntity = appModel.entityNamed(SSOrganisation);
appEntity.setName(Organisation);
return;
}
It looked like it might be working until I threw that into a D2W front-end with
the same models and database. Just after login, as it builds the
ERMODQueryEntitiesPage, I get this:
NullPointerException
at
com.webobjects.eoaccess.EODatabase.addModelIfCompatible(EODatabase.java:575)
... skipped 15 stack elements
at
com.webobjects.eocontrol.EOObjectStoreCoordinator.objectsWithFetchSpecification(EOObjectStoreCoordinator.java:488)
at
com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:4069)
at er.extensions.eof.ERXEC.objectsWithFetchSpecification(ERXEC.java:1215)
at
com.webobjects.eocontrol.EOEditingContext.objectsWithFetchSpecification(EOEditingContext.java:)
at
net.logicsquad.webobjects.auth.model.auth._Person.fetchPersons(_Person.java:442)
at
net.logicsquad.webobjects.auth.model.auth._Person.fetchAllPersons(_Person.java:436)
at
net.logicsquad.webobjects.auth.model.auth._Person.fetchAllPersons(_Person.java:432)
at
net.logicsquad.survstar.DirectAction.canUseBootstrapCredentials(DirectAction.java:108)
at net.logicsquad.survstar.DirectAction.loginAction(DirectAction.java:143)
... skipped 4 stack elements
at
com.webobjects.appserver.WODirectAction.performActionNamed(WODirectAction.java:144)
at
er.extensions.appserver.ERXDirectAction.performActionNamed(ERXDirectAction.java:401)
at
er.directtoweb.ERD2WDirectAction.performActionNamed(ERD2WDirectAction.java:463)
... skipped 9 stack elements
Any thoughts on the appropriate additional surgery?
--
Paul Hoadley
http://logicsquad.net/
___
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Re: Using composition instead of inheritance
Paul, My first question would be - how do you actually benefit from having this data separated? Is there a reason that you don't just create a new entity for the new project that can represent the entire organization? If the reason is that you have code that you would typically use in more than one project, I would consider building that into POJOs . In general, I find that the benefits of splitting up entities (either through inheritance OR composition) seldom outweighs the benefits of having them together, unless there are some circumstances that totally warrant it. If you could provide more information on the perceived benefits, people might be able to help you better. Ken On May 29, 2012, at 1:16 AM, Paul Hoadley wrote: Hello, I'm after some general modelling advice. I've been using inheritance for years to model app-specific versions of a framework-level Person (user) entity. This works well enough, though it presents the same small headaches time after time for each new application. I also have a framework-level Organisation entity to model a user's organisation. I need to customise this for a new application, and I thought this time I would use composition instead of inheritance—I'll create a new FooOrganisation entity which has a to-one relationship to Organisation (without the inverse relationship), and then the additional attributes and/or relationships which are app-specific. The application is still in development, but there's a demo deployment, and while I _can_ wipe the database, there are existing Organisation EOs in it, and it would be nice if I didn't have to. I'm using migrations, so I can perform any one-off fix-ups in a post-migration step. So, do people model like this? Are there any pitfalls? What's the best way to ensure referential integrity, such that Organisation and FooOrganisation remain 1-1—'owns destination' and 'propagates primary key'? (Selecting those will require I scrap the DB and create the FooOrganisations first, won't it?) Would dynamically adding some properties to the model at runtime be a better option here if I just want to store, say, a few limited extra attributes on an entity? -- Paul Hoadley http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/kenlists%40anderhome.com This email sent to kenli...@anderhome.com ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
This is the problem that Partial Entities were attempting to solve ( http://webobjects.mdimension.com/hudson/job/Wonder/javadoc/er/extensions/partials/package-summary.html ). I would consider it experimental, but if anyone wants to take it and finish it, go for it. ms On May 29, 2012, at 1:40 PM, Ken Anderson kenli...@anderhome.com wrote: Paul, My first question would be - how do you actually benefit from having this data separated? Is there a reason that you don't just create a new entity for the new project that can represent the entire organization? If the reason is that you have code that you would typically use in more than one project, I would consider building that into POJOs . In general, I find that the benefits of splitting up entities (either through inheritance OR composition) seldom outweighs the benefits of having them together, unless there are some circumstances that totally warrant it. If you could provide more information on the perceived benefits, people might be able to help you better. Ken On May 29, 2012, at 1:16 AM, Paul Hoadley wrote: Hello, I'm after some general modelling advice. I've been using inheritance for years to model app-specific versions of a framework-level Person (user) entity. This works well enough, though it presents the same small headaches time after time for each new application. I also have a framework-level Organisation entity to model a user's organisation. I need to customise this for a new application, and I thought this time I would use composition instead of inheritance—I'll create a new FooOrganisation entity which has a to-one relationship to Organisation (without the inverse relationship), and then the additional attributes and/or relationships which are app-specific. The application is still in development, but there's a demo deployment, and while I _can_ wipe the database, there are existing Organisation EOs in it, and it would be nice if I didn't have to. I'm using migrations, so I can perform any one-off fix-ups in a post-migration step. So, do people model like this? Are there any pitfalls? What's the best way to ensure referential integrity, such that Organisation and FooOrganisation remain 1-1—'owns destination' and 'propagates primary key'? (Selecting those will require I scrap the DB and create the FooOrganisations first, won't it?) Would dynamically adding some properties to the model at runtime be a better option here if I just want to store, say, a few limited extra attributes on an entity? -- Paul Hoadley http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/kenlists%40anderhome.com This email sent to kenli...@anderhome.com ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/mschrag%40pobox.com This email sent to msch...@pobox.com ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
Hi Ken, On 30/05/2012, at 3:10 AM, Ken Anderson wrote: My first question would be - how do you actually benefit from having this data separated? I don't. It's just a side effect of wanting to have an app-specific EO based on a more general framework-level EO. Is there a reason that you don't just create a new entity for the new project that can represent the entire organization? Just code/entity reuse. I already have a framework-level Organisation entity. It's just that different applications want to be able to hang different attributes and relationships off it. If the reason is that you have code that you would typically use in more than one project, I would consider building that into POJOs . In general, I find that the benefits of splitting up entities (either through inheritance OR composition) seldom outweighs the benefits of having them together, unless there are some circumstances that totally warrant it. If you could provide more information on the perceived benefits, people might be able to help you better. It's basically the exact scenario described in the Javadocs for Mike Schrag's partial entities: A very common case where this becomes useful is that of a Person entity. Person is an entity that is used in many different scenarios, each of which requires additional attributes and relationships. For instance, you may have a task management application and you want to embed your calendaring framework into it. The common Person base entity may have username and password attributes, the tasking application may add an activeTasks relationship, and the calendaring framework may add a scheduledEvents relationship as well as dayStartTime and dayEndTime attributes. Note that partials are not designed to address the issue of roles, where different people in the system may have different roles at different times. Partial entities are designed to address the issue of combining high level modules together to form more complex static entity declarations. That's precisely the problem I'm trying to solve. Until now I've done it via inheritance. I was going to see if composition was any easier, but after diving into it, it seems to be about as hairy as inheritance, just in different places. What I settled on was adding a new column to the Organisation table using a migration, and adding a matching attribute to the model at application startup. Apart from not having the convenience of the Velocity template methods, it certainly seems to work fine. I'm still interested to know what other people are doing, though. Given the problem described by Mike above, how are people solving it? -- Paul. http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
In the absence of the fancier solution (something like partial entities), I think I would make an app variant of the entity (where the class of the app one extends the class of the framework one) and model-rewrite the non-app variant to be the app variant. ms On May 29, 2012, at 6:22 PM, Paul Hoadley pa...@logicsquad.net wrote: Hi Ken, On 30/05/2012, at 3:10 AM, Ken Anderson wrote: My first question would be - how do you actually benefit from having this data separated? I don't. It's just a side effect of wanting to have an app-specific EO based on a more general framework-level EO. Is there a reason that you don't just create a new entity for the new project that can represent the entire organization? Just code/entity reuse. I already have a framework-level Organisation entity. It's just that different applications want to be able to hang different attributes and relationships off it. If the reason is that you have code that you would typically use in more than one project, I would consider building that into POJOs . In general, I find that the benefits of splitting up entities (either through inheritance OR composition) seldom outweighs the benefits of having them together, unless there are some circumstances that totally warrant it. If you could provide more information on the perceived benefits, people might be able to help you better. It's basically the exact scenario described in the Javadocs for Mike Schrag's partial entities: A very common case where this becomes useful is that of a Person entity. Person is an entity that is used in many different scenarios, each of which requires additional attributes and relationships. For instance, you may have a task management application and you want to embed your calendaring framework into it. The common Person base entity may have username and password attributes, the tasking application may add an activeTasks relationship, and the calendaring framework may add a scheduledEvents relationship as well as dayStartTime and dayEndTime attributes. Note that partials are not designed to address the issue of roles, where different people in the system may have different roles at different times. Partial entities are designed to address the issue of combining high level modules together to form more complex static entity declarations. That's precisely the problem I'm trying to solve. Until now I've done it via inheritance. I was going to see if composition was any easier, but after diving into it, it seems to be about as hairy as inheritance, just in different places. What I settled on was adding a new column to the Organisation table using a migration, and adding a matching attribute to the model at application startup. Apart from not having the convenience of the Velocity template methods, it certainly seems to work fine. I'm still interested to know what other people are doing, though. Given the problem described by Mike above, how are people solving it? -- Paul. http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/mschrag%40pobox.com This email sent to msch...@pobox.com ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
On 30/05/2012, at 7:55 AM, Mike Schrag wrote: In the absence of the fancier solution (something like partial entities), I think I would make an app variant of the entity (where the class of the app one extends the class of the framework one) and model-rewrite the non-app variant to be the app variant. What do you mean by the last bit: model-rewrite the non-app variant to be the app variant? -- Paul. http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
This is the problem that Partial Entities were attempting to solve ( http://webobjects.mdimension.com/hudson/job/Wonder/javadoc/er/extensions/partials/package-summary.html ). I would consider it experimental, but if anyone wants to take it and finish it, go for it. By experimental, is it closer to you would be crazy to use this right now or this probably works? Roughly what remains to be done? Meaning i have no idea what state this is in. It basically worked for my test cases, but I never used it in real life. I have no idea if it has since been broken by later changes to wonder (this was years ago). Certainly a decent starting point if you wanted to try to ship something based on the concept. ms ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
FrameworkPerson (and all code in the framework refers to that) and AppPerson (extends FrameworkPerson class, and all app code refers to that). When your models load, replace FrameworkPerson entity with AppPerson entity, so fetches for FrameworkPerson are secretly the equivalent to what AppPerson fetches would be. This is assuming EVERY row in your person table is an AppPerson in any given app. ms On May 29, 2012, at 6:28 PM, Paul Hoadley pa...@logicsquad.net wrote: On 30/05/2012, at 7:55 AM, Mike Schrag wrote: In the absence of the fancier solution (something like partial entities), I think I would make an app variant of the entity (where the class of the app one extends the class of the framework one) and model-rewrite the non-app variant to be the app variant. What do you mean by the last bit: model-rewrite the non-app variant to be the app variant? -- Paul. http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: Using composition instead of inheritance
On 30/05/2012, at 8:01 AM, Mike Schrag wrote: FrameworkPerson (and all code in the framework refers to that) and AppPerson (extends FrameworkPerson class, and all app code refers to that). When your models load, replace FrameworkPerson entity with AppPerson entity, so fetches for FrameworkPerson are secretly the equivalent to what AppPerson fetches would be. This is assuming EVERY row in your person table is an AppPerson in any given app. Thanks Mike. -- Paul. http://logicsquad.net/ ___ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
