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Why am I getting JPA LazyInitializationException when using Spring OpenEntityManagerInViewFilter?

Answer 1

A:

This appears to be a problem with your transaction scope. In Hibernate / JPA a one-to-many reference is by default lazy. This means that the entities in the collection are not retrieved until their are accessed. Accessing lazily loaded values is only possible within the same transaction in which you loaded the parent object.

In your case you retrieve an instance of Dealer in the prepare() method, but you access the inventoryParts in a different method of your Action. There is a little too few context here but it is likely that those two things happen in a different transaction, resulting in the LazyInitializationException.

You could take a look at your transaction propagation or take a different approach in accessing the inventoryParts, for instance adding lazy = false like below:

@OneToMany(cascade = CascadeType.ALL, mappedBy = "dealer", lazy = false)
private Set<InventoryPart> inventoryParts;

This might however not be what you want, because it always loads ALL InvertoryParts associated to the Dealer. You can also make sure you access the collection within the same transaction by accessing it in the prepare() method.

Just some different approaches. There is no best answer here, because your performance might be at stake.

Jaap Coomans 2010-10-25 13:36:27

This is not totally accurate. Accessing a lazily loaded association only requires an active EntityManager, which is the point of using the OEIV here (and a lazy association can be loaded in another transaction than the one used to load the parent, as long as you have an active EntityManager).

Pascal Thivent 2010-10-25 15:33:00

That's what I understood as well. OEIV was meant to address this problem specifically, so I have some sort of config problem...

Griff 2010-10-25 15:56:11

You're correct, I overlooked the OEIV part, which is quite essential to the question.... Sorry!

Jaap Coomans 2010-10-28 08:44:25

Answer 2

+1 A:

Is it possible that getAuthenticatedUser() is returning a detached user object? Then when you do user.getDealer() the dealer object will also be detached leading to the lazy load exception.

Pablojim 2010-10-26 21:28:34

Maybe. The user object is not a JPA managed object, it is JDBC managed. There are 2 places when the user object has the dealer object set to it. One is in the spring UserDetailsContextMapper, and the other is in a struts action. When the dealer logs in, their dealer object is set into the permissioned user so that it doesn't have to be retrieved, and so that it can be used to limit queries to just their data. When a system admin logs in, the sysadmin person selects a dealer to manage from a list, and I set the dealer object to the user so I can reuse artifacts. See Addl. code above

Griff 2010-10-27 19:43:57

Ok, so the LazyInitializationException only happens when the dealer object is set into the PermissionedUser object in the struts action, not when the dealer is set into the PermissionedUser in the UserDetailsContextMapper. So, this is starting to look like the right answer. Why would the object be detached in the struts object? Is it because my struts method is get* and that is a read-only transaction in the applicationContext.xml file?

Griff 2010-10-27 21:48:56

Ok, the problem is related somehow to transactions, so I guess I don't understand this as well as I wish I did. In my original code, the problem only showed up in the struts action. By using the struts Prepareable interceptor and the paramsPrepareParamsStack, I was retrieving the dealer in the prepare method, and setting the dealer to the user in a different method. When I moved the method call to set the dealer to the user object in the same transactional method, the LazyInitializationException disappears. Refactored working code posted above.

Griff 2010-10-27 22:26:06

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Why am I getting JPA LazyInitializationException when using Spring OpenEntityManagerInViewFilter?

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