Jpa entitymanager merge not updating


01-Nov-2019 01:01

Hibernate was the most successful Java ORM implementation.No wonder that the specification for Java persistence API (JPA) was heavily influenced by the Hibernate API.As an example entity, we will use a simple annotation-mapped entity variable references the actual persisted object.

The session is a logical transaction, which boundaries are defined by your application’s business logic.The spec does not state that the id will be generated right away, regardless of the id generation strategy.The specification for the method allows the implementation to issue statements for generating id on commit or flush, and the id is not guaranteed to be non-null after calling this method, so you should not rely upon it.When you work with the database through a persistence context, and all of your entity instances are attached to this context, you should always have a single instance of entity for every database record that you’ve interacted during the session with.

In Hibernate, the persistence context is represented by or any of those methods to get these changes to the database: all you need is to commit the transaction, or flush or close the session, when you’re done with it.An entity that passed through such serialization/deserialization will appear in a methods, because they are standardized and guaranteed to conform to the JPA specification.They are also portable in case you decide to switch to another persistence provider, but they may sometimes appear not so useful as the “original” Hibernate methods, .Apart from object-relational mapping itself, one of the problems that Hibernate was intended to solve is the problem of managing entities during runtime.



BTW, you can find a different angle on the saveOrUpdate vs. merge problem in. do not invoke any EntityManager method; the JPA provider will automatically.… continue reading »


Read more

Hello. I have a problem with the EntityManager.merge function. I set a property value of an entity statement with an other entity.… continue reading »


Read more