Hi all,

I just wondered whether there's a helper class or an other mechanism in hibernate which calculates hashCode() values and performs the equals()-method.

If not, take my question as a feature request.
It shouldn't be too difficult to build since hibernate has all needed information about the objects properties in its mapping files and already makes strong use of reflection.

Furthermore all information about the consideration of detail objects in equals() and hashCode() can be retrieved from the hibernate mappings, too. I.e. the question whether the hashcode of associated detail objects shoud be included in an objects hashcode can be answered by the cascade-attribute of the association mapping.

Bye, Stefan

hbm2java has a simple equals and hashcode generation.

and yes hbm.xml contains much information that can be used to perform this - but remember that writing automated equals and hashcode can be hard since sometimes you don't have all the properties set - e.g. when you are using assigned ids...

Any patches and strategies for doing this the right way is welcome!

Thanks for your quick reply. I really appreciate that your working on weekends (just like I'm doing now ;-)

I didn't think of generated code for the both methods.
I thought of helper methods which examine an objects properties online.

I just learned that the correct implementation of hashCode() and equals() is crucial for hibernate collections to work.
So I have to implement them thoroughly. Since I'm a lazy guy I'll try to delegate these tasks to a helper object which might use the net.sf.hibernate.persister.ClassPersister class.
Of course I don't know yet if it will work but if it does I'll post the code here.

Stefan

You could implement something like this using Hibernate's metadata API. However, think carefully about the philosophical implications of making your domain model dependant upon Hibernate classes!

...and performance!

Well, that has already happended because all classes of my business model implement the interface net.sf.hibernate.Lifecycle in order to observe the persistence state of an object (is it new, is is changed, stored or deleted?) I implemented a common super class for this purpose.
BTW: Is there a better solution for this problem?

I didn't even start with my hashCode-equals-helper class. I think the most difficult problem is the handling of associated objects so I might omit a solution in the first shot.
Maybe I will totally fail and write 16 (the number of my business classes) hashCode-equals-pairs by hand. We'll see...