On 16 mai 2012, at 14:28, Scott Marlow wrote: > According to JPA 2.0 specification section 3.2.7.1, when merging a > detached entity with lazy associations that haven't been fetched: > > " > The persistence provider must not merge fields marked LAZY that have not > been fetched: it must ignore such fields when merging. > " > > > After merging an entity, will accessing one of the entities LAZY fields > (that was previously not fetched) result in a lazy initialization error > or will we try to fetch from the database? The latter.

On 05/16/2012 11:00 AM, Scott Marlow wrote: > On 05/16/2012 10:16 AM, Emmanuel Bernard wrote: >> >> On 16 mai 2012, at 14:28, Scott Marlow wrote: >> >>> According to JPA 2.0 specification section 3.2.7.1, when merging a >>> detached entity with lazy associations that haven't been fetched: >>> >>> " >>> The persistence provider must not merge fields marked LAZY that have not >>> been fetched: it must ignore such fields when merging. >>> " >>> >>> >>> After merging an entity, will accessing one of the entities LAZY fields >>> (that was previously not fetched) result in a lazy initialization error >>> or will we try to fetch from the database? >> >> The latter. > > The latter isn't working for me yet (I get a > "LazyInitializationException: failed to lazily initialize a collection > of role"), I'll try recreating in a Hibernate ORM test case. Steve pointed out that the entity passed into EntityManager.merge() will not be attached, instead the merged state is returned and should be used.  After I adjusted for that, I can access the lazy field.  :)