Update Entity using EntityManager JPA EclipseLink

Question

I am getting a ERROR: duplicate key value violates unique constraint "users_pkey" Detail: Key (userid)=(2701) already exists. whenever i use the persist model to update my user entity.

In the code sample below: SetLoginAttempts takes in a user entity that has been queried and when i start the transaction i simply set one of the entity's fields and call persist(), then commit the transaction.

/**
* @param user
* @param attemptNumber
*/
@Transactional
public void setLoginAttempts(Users user, int attemptNumber){         
    user.setLoginAttempts(attemptNumber);
    System.out.println(user);
}

Here is how i reference and grab the entity manager:

eFactory = Persistence.createEntityManagerFactory("persistenceUnit");
eManager = eFactory.createEntityManager();

When looking at the stack trace, i noticed that the commit actually injects an insert

Call: INSERT INTO USERS (userID, EMAIL, ISLOCKED, LOGINATTEMPTS, passwordHash, passwordSalt, USERNAME, version) VALUES (?, ?, ?, ?, ?, ?, ?, ?)
bind => [2701, [email protected], false, 1, $shiro1$SHA-256$500000$6mqzZ/d/3BLQuJqLh1dDhQ==$NKW7Z++o/JTvf884aDWhP3Uhpyb5fTPMrm4joWnw7nI=, [B@1a8e3115, admin, 1]

What is the proper way to reference an entity manager in Spring roo, update a field and commit the changes?

Edit

I added the @Transactional to the method and the stack trace shows that this is creating the entity manager instance:

2012-03-14 23:49:15,503 ["http-bio-8080"-exec-18] DEBUG org.springframework.orm.jpa.JpaTransactionManager - Creating new transaction with name [org.bixin.dugsi.service.UserService.setLoginAttempts]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT; ''
2012-03-14 23:49:15,503 ["http-bio-8080"-exec-18] DEBUG org.springframework.orm.jpa.JpaTransactionManager - Opened new EntityManager [org.eclipse.persistence.internal.jpa.EntityManagerImpl@46b9979b] for JPA transaction
[EL Finer]: 2012-03-14 23:49:15.503--ServerSession(2128384958)--Thread(Thread["http-bio-8080"-exec-18,5,main])--client acquired: 1116759395
[EL Finer]: 2012-03-14 23:49:15.503--ClientSession(1116759395)--Thread(Thread["http-bio-8080"-exec-18,5,main])--acquire unit of work: 368076985
2012-03-14 23:49:15,503 ["http-bio-8080"-exec-18] DEBUG org.springframework.orm.jpa.JpaTransactionManager - Not exposing JPA transaction [org.eclipse.persistence.internal.jpa.EntityManagerImpl@46b9979b] as JDBC transaction because JpaDialect [org.springframework.orm.jpa.DefaultJpaDialect@c595bcd] does not support JDBC Connection retrieval
Email: [email protected], Id: 2701, IsLocked: false, LoginAttempts: 2, Password: $shiro1$SHA-256$500000$6mqzZ/d/3BLQuJqLh1dDhQ==$NKW7Z++o/JTvf884aDWhP3Uhpyb5fTPMrm4joWnw7nI=, PasswordSalt: [B@1a8e3115, Roles: 0, Username: admin, Version: null
2012-03-14 23:49:15,503 ["http-bio-8080"-exec-18] DEBUG org.springframework.orm.jpa.JpaTransactionManager - Initiating transaction commit
2012-03-14 23:49:15,503 ["http-bio-8080"-exec-18] DEBUG org.springframework.orm.jpa.JpaTransactionManager - Committing JPA transaction on EntityManager [org.eclipse.persistence.internal.jpa.EntityManagerImpl@46b9979b]
[EL Finer]: 2012-03-14 23:49:15.503--UnitOfWork(368076985)--Thread(Thread["http-bio-8080"-exec-18,5,main])--begin unit of work commit
[EL Finer]: 2012-03-14 23:49:15.503--UnitOfWork(368076985)--Thread(Thread["http-bio-8080"-exec-18,5,main])--end unit of work commit
[EL Finer]: 2012-03-14 23:49:15.504--UnitOfWork(368076985)--Thread(Thread["http-bio-8080"-exec-18,5,main])--resume unit of work
2012-03-14 23:49:15,504 ["http-bio-8080"-exec-18] DEBUG org.springframework.orm.jpa.JpaTransactionManager - Closing JPA EntityManager [org.eclipse.persistence.internal.jpa.EntityManagerImpl@46b9979b] after transaction
2012-03-14 23:49:15,504 ["http-bio-8080"-exec-18] DEBUG org.springframework.orm.jpa.EntityManagerFactoryUtils - Closing JPA EntityManager
[EL Finer]: 2012-03-14 23:49:15.504--UnitOfWork(368076985)--Thread(Thread["http-bio-8080"-exec-18,5,main])--release unit of work

But still no updates to the DB even after refresh, why isnt the transaction closing and updating the DB?

Answer 1

JPA exposes two methods... persist() and merge()

Persist: Persist is responsible for inserting new rows to DB and then associating the Entity with state in JPA session.

Merge: Merge takes existing Entity and updates the DB row. It also updates the state of the entity in JPA session.

I think The user already exists in your database table. In order to update the login count, you can use the merge() method on EntityManager.