I posted this before in a response to another post, but didn't get any replies, so I'm posting it again as a new post

According to Gavin,



That is a little easier said than done.

It is our practice to always make a copy of a collection passed in from a setter or out through a getter. I don't have TOO much of a problem doing this for the setter, since our setters for collections are private (only exist for the persistence implementation). But I have a hard time passing the same instance out of a getter that we are refering to in our class. Someone could modify the contents, I have to make sure the collection is thread safe, etc... I am curious to know why I can't change the reference, if I'm just copying the data. I can't think of a good reason why hibernate would need to refer to the same instance, but I'm sure you have one. Could someone suggest a workaround (i.e. create an immutable implementation of List and pass that to Hibernate; how would hibernate create an instance of that collection on retrieve.). Otherwise, I suppose we'll have to explictly delete orphaned objects. Thanks.

I quote Gavin (You can recognize the style ;-))

Do NOT do this ever. Hibernate needs the original collection instance - it carries extra state that Hibernate needs.

If you absolutely insist on this shitty Joshua Block defensive coding style (which is only useful for people who don't write unit tests), then either

* give Hibernate its own accessors
* use access="direct" in Hibernate 2.1

P.S. sorry for gratuitous joshua block diss it was quite unnecessary ;)

p.s.s. second apology, its actually called access="field"

Gavin,

Are you saying that we could have problems if we change the collection reference even if we are not using all-delete-orphan?

yes. this is in the FAQ.