[hibernate-dev] JPA merge question about detached entity with lazy fields that haven't been fetched...

Scott Marlow smarlow at redhat.com
Wed May 16 11:15:48 EDT 2012

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, 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.  :)

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