Hi Andrew, Sorry for delayed reply.
The current set of accessors 'readProperty'/'readPropertyDirectly' exists for the benefit of the framework. 'readNestedProperty' is in a different category - it is a utility method and is never used by Cayenne internally (not counting unit tests). FWIW, I'd be willing to deprecate 'CDO.readNestedProperty' and just keep its static version in the utility class. So an inconsistency you pointed to - 'readProperty' being limited to mapped properties, while 'readNestedProperty' being a mix of mapped and unmapped properties, to me is purely a *naming* inconsistency. With that in mind us not having the suggested extra methods in Cayenne shouldn't prevent the customizations that you have in mind ... I think (?) You can always create a custom common superclass with a custom path navigation strategy, ignoring 'readNestedProperty' if it gets in the way (MyDataObject extends CayenneDataObject), but I am not convinced Cayenne should be the place for this code. It is a persistence framework, and staying focused on persistence is important IMO. We had a discussion in the context of 'cayenne-lifecyce' recently on what should be in Cayenne core, and what is an "extension". I think here we are down to this choice also. Let me know if I am still missing the point of your suggestion. Andrus On Nov 17, 2010, at 1:12 PM, Andrew Lindesay wrote: > Hello; > > I've been playing around with trying to override some behaviours in the area > of "read property" on the data objects, but I think I have come to the > conclusion that the way it is rigged-up makes this a little difficult. I'd > like to suggest a change (which is probably more appropriate for 3.1 owing to > it being a non-trivial change in behaviour) and I would be interested in any > feedback. Here is the text of the ticket... > > --- > > There is an issue that a data object (DO) uses the "readProperty()" method in > its accessors such as "getStartTimestamp()"/"getArtist()" etc... The > "readNestedProperty()" does some extra things like using reflection to get at > non-modelled accessors, but "readProperty()" does not. This is an > inconsistency. > > Simply adding the additional reflection to "readProperty()" is not a good > idea because in the case where an object is not yet related to the model, an > infinite loop can result. Particularly in the case where a data object is > not yet added to an object context, the logical condition around stopping > this infinite loop is not able to be identified. > > My suggestion is to add a protected "readPropertyStored()" which will be used > by the accessors such as "getStartTimestamp()"/"getArtist()". This method > will ~not~ use reflection, but "readProperty()" will do the additional > reflection if necessary. The "readPropertyStored()" will continue to invoke > "readPropertyDirectly()". > > In addition, the "extra reflection" from "readProperty()" would be serviced > through two additional methods on the data object; > > readPropertyDerived(..) > > For the case of the "readNestedProperty(..)" the use of reflection into an > object which is ~not~ a data object will be serviced through; > > readNestedPropertyFromNonDataObject(..) > > Together these changes will allow for consistenecy in the 'read property' > behaviour and will also allow third parties to more easily extend Cayenne's > 'read property' behaviors in order to support more sophisticated 'read > property' behaviour. > > This is a change in behavior and generated DAO classes would need to be > modified to use 'readPropertyStored()' instead of 'readProperty()'. > > --- > > cheers. > > -- > Andrew Lindesay > www.silvereye.co.nz >
