Lazy loading working in non-transactional class/method in Hibernate

Question

I am working in Spring-Hibernate application. Flow is as usual: Controller --> Service --> DAO.

I have annotated Service layer class with @Transactional, thereby marking every method transactional in that class.In service class, I made a DAO call to get some domain object and then converting it into DTO/VO object which will be passed to controller.For converting domain object to DTO, I have written another custom static class(class having only static methods) like ObjectMapper which will do this conversion.

Now, domain object has some child object(One to Many) which is lazily loaded. So, when in ObjectMapper, i access that child getter method, an extra database call is issued, which is working fine. What I don't understand is that since ObjectMapper is not transactional, I was expecting some exception to be thrown like Session is closed while making database call to fetch child object from database.I am using getCurrentSession of Session Factory in DAO.

Can someone please explain me this behavior?

if the relation is one-to-one or Many-to-One it's by default eagerly fetch — JEY
– JEY, Commented Sep 30, 2015 at 7:19
Are you sure you don't access to this collection before giving it your ObjectMapper ? Does you ObjectMapper call inside your service ? — JEY
– JEY, Commented Sep 30, 2015 at 7:22
Yes, I call ObjectMapper inside service, but getter of child object is invoked inside ObjectMapper — Anand
– Anand, Commented Sep 30, 2015 at 7:46

Raphael Roth · Accepted Answer · 2015-09-30 07:42:01Z

1

I suppose you either call your ObjectMapper from the transactional Service method (you should) or if not, maybe you are enabled "hibernate.enable_lazy_load_no_trans" which keeps the hibernate session open

answered Sep 30, 2015 at 7:42

Raphael Roth

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3 Comments

Anand Over a year ago

Yes, I am calling ObjectMapper from transactional Service method but still should it work?

Raphael Roth Over a year ago

yes, as long as you call the mapper from the transactional method then the session is open for sure

Anand Over a year ago

But somewhere I read that @Transactional doesn't work for method call inside method since Transactional is run by Spring AOP.

dunni · Accepted Answer · 2015-09-30 07:22:50Z

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As long as the call to the static class/method, which transforms your objects, is made in the transactional method of the DAO, the session is still open and will be used for the database calls.

answered Sep 30, 2015 at 7:22

dunni

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4 Comments

Anand Over a year ago

But ObjectCaller is neither Spring bean or @transactional..so how come it is working??

JEY Over a year ago

There you go every thing that is called inside a transactional method is transactional. The transaction start before the call of your method and stop after the method return.

Anand Over a year ago

But somewhere I read that @Transactional doesn't work for method call inside method since Transactional is run by Spring AOP.

dunni Over a year ago

Yes, if there is no open transaction and you want that method call to start a new one, then it will not work. But this is different from your case.

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