Hibernate merge not updating abledating forum
Control flow analysis has become much smarter and now detects a wider variety of problems in the code.For example, if Collection#is Empty() returns true, the IDE understands that there are no elements in that collection to iterate over.update can fail if an instance of the object is already in the session. It merges the changes of the detached object with an object in the session, if it exists.
In order //to avoid this exception we are using merge like given below instead of session.update(emp1); session2.merge(emp1); //it merge the object state with emp2 session2.update(emp1); //Now it will work with exception In the hibernate session we can maintain only one employee object in persistent state with same primary key, while converting a detached object into persistent, if already that session has a persistent object with the same primary key then hibernate throws an Exception whenever update() method is called to reattach a detached object with a session.Update: if you are sure that the session does not contains an already persistent instance with the same identifier,then use update to save the data in hibernate Merge: Suppose we are creating a session and load an employee object. If we close the session at this point and we edit state of object and tried to save using update() it will throw exception.To make object persistent we need to open another session. So if we want to update present object with previous object changes we have to use merge() method.In this case we need to call merge() method instead of update() so that hibernate copies the state changes from detached object into persistent object and we can say a detached object is converted into a persistent object.Hibernate handles persisting any changes to objects in the session when the session is flushed.