Entitymanager persist merge update

Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 9 years, 10 months ago. Active 5 years, 4 months ago. Viewed 43k times. Edit I added the Transactional to the method and the stack trace shows that this is creating the entity manager instance: , ["http-bio"-exec] DEBUG org. JpaTransactionManager - Creating new transaction with name [org. Vojtech Ruzicka Warz Warz 6, 14 14 gold badges 65 65 silver badges bronze badges.

Add a comment. Active Oldest Votes. JPA exposes two methods Ameya Ameya 4 4 silver badges 6 6 bronze badges. I just tried replacing persist with merge and it seems as nothing happened.

Looking at the stack trace again and i get this "Initiating a transaction roll back" for some reason? Creating a new entity bean involves inserting a new row in the database. To see how the merge method works consider the following example which persists a Book entity in one transaction, then it modifies it while the entity is in the detached state, and pass the detached entity to merge in a subsequence Persistence Context. Notice that the entity reference returned by merge is different than the detached one we passed to the merge method.

For this reason, you should prefer using update when you are sure that there is no entity reference already attached to the currently running Persistence Context and that the detached entity has been modified.

If you enjoyed this article, I bet you are going to love my Book and Video Courses as well. To persist an entity, you should use the JPA persist method. To copy the detached entity state, merge should be preferred. The update method is useful for batch processing tasks only. The save and saveOrUpdate are just aliases to update and you should not probably use them at all.

Some developers call save even when the entity is already managed, but this is a mistake and triggers a redundant event since, for managed entities, the UPDATE is automatically handled at the Persistence context flush time. Your email address will not be published. Notify me of follow-up comments by email. This site uses Akismet to reduce spam.

Learn how your comment data is processed. Vlad Mihalcea. Leave a Comment Posted on February 27, by vladmihalcea. Insert details about how the information is going to be processed. Asked 9 years, 2 months ago. Active 9 years, 2 months ago. Viewed 45k times. Buhake Sindi Timo Timo 1 1 gold badge 2 2 silver badges 5 5 bronze badges. The above code is OK, except that the call to personDao. The getPersonById method could also be reduced to em. Addendum: this is definitely explained in the documentation.

See docs. Add a comment. Active Oldest Votes. Two scenarios might pop up for you. You may want to change a property of the object, and only that property.

If this is the case you want to use the method: find, modify, flush, commit. You may want to use the objects properties to update the item. If this is the case you want to use the method: merge, optionally modify, flush, commit.

Found my solution, finally I used entityManager. Glad you found a solution.