Entitymanager

EntityManager manages the lifecycle of an entity and performs all operations associated with the entity. EntityManager Meaning An entity manager manages the lifecycle of an entity and performs all operations associated with the entity. The entity manager performs operations such as storing an entity in a database or reading an entity from a database. Key Features The key features of an entity manager are as follows: Persist: Stores an entity in a database. Query: Reads an entity from a database. Update: Modifies an entity stored in a database. Delete: Removes an entity from a database. Example 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 @Repository public class UserRepository { @PersistenceContext private EntityManager em; public void save(User user) { em.persist(user); } public User findById(Long id) { return em.find(User.class, id); } public void update(User user) { em.merge(user); } public void delete(User user) { em.remove(user); } } The entity manager can be injected using the @PersistenceContext annotation. The entity manager can be used to perform operations such as saving, querying, modifying, and deleting entities. The entity manager operates in a transaction unit, and the entity manager is automatically closed when the transaction ends. ...