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I have a method annotated with @Transactional. I retrieve an object from my DB, change a field, and then return from the method. Without saving my object, the database gets updated anyway which is strange.
Could you please tell me how to avoid this beahvior?
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The default @Transactional settings are: The propagation setting is PROPAGATION_REQUIRED. The isolation level is ISOLATION_DEFAULT. The transaction is read/write.
So when you annotate a method with @Transactional , Spring dynamically creates a proxy that implements the same interface(s) as the class you're annotating. And when clients make calls into your object, the calls are intercepted and the behaviors injected via the proxy mechanism.
The @Transactional annotation makes use of the attributes rollbackFor or rollbackForClassName to rollback the transactions, and the attributes noRollbackFor or noRollbackForClassName to avoid rollback on listed exceptions. The default rollback behavior in the declarative approach will rollback on runtime exceptions.
"@Transactional" as itself on any isolation level doesn't enabling any locking. To achieve locking behaviour you should use "@Lock" annotation or use " for update" in your query.
This a normal JPA behavior.
Once you retrieve an object via find() or so, that object is regarded as attached, or belongs to a persistence context. Once you exit the method the @Transactional triggers a Spring transaction management aspect which flushes every "dirty" object to database and commits the transaction. Since your object is already changed within the context of the persistence context and the transaction, the changes are saved to the database even without the need to explicitly call a save method.
If you want to change your object without affecting the database, you have two options:
@Transactional
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