Forcing a method to be non-transactional in JPA (Eclipselink)

Question

Hi,

I am developing an application using Eclipselink and as part of the app I need to be able to manipulate some of the objects which involves changing data without it being persisted to the database (i merging/changing objects for some batch generation processes).

I am reluctant to change the data in the Entity objects, as there is a risk that even though i have not marked the methods as @Transactional, this method could in the future be inadvertantly called from within a transactional method and these changes could be persisted.

So my question is, is there anyway to get around this? Such as force a method to always be non-transactional regardless; terminate any transactionality as soon as the method is started; etc.

I know there is a .detach() method that can detach the objects from the Entity Manager, however, there are many objects and this seems like a potentially error prone fail-safe on my code.

Answer 1

If this is spring, you have

@Transactional(propagation=Propagation.NOT_SUPPORTED)

Execute non-transactionally, suspend the current transaction if one exists. Analogous to EJB transaction attribute of the same name.

If it's EJB, you have a transaction attribute of the same name.

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Anyway, instead of playing around with transactions, you can simply clone your object and modify the required data. Deep cloning can be achieved via commons-lang SerializationUtils.

Answer 2

I'm not sure to understand your use case but I wouldn't mess with transaction here and either:

• Not merge changes made to entities ~or~
• refresh any changes made to entities before a merge (but why would you call merge?) ~or~
• Work on non-managed copies of entities ~or~

• Declare some classes are Read-Only (EclipseLink specific, see Declaring Read-Only Classes and How to Use the @ReadOnly Annotation). From the doc:

  Any changes made within a managed instance in a transaction or to a detached instance and merged will have no effect in the context of a read-only entity class.