No entitymanager with actual transaction available for current thread – cannot reliably process ‘persist’ call

When the error message “No EntityManager with actual transaction available for current thread – cannot reliably process ‘persist’ call” is encountered, it means that there is an issue with the transaction management or the current thread does not have access to a valid EntityManager.

To better understand this error, let’s break it down:

• No EntityManager: EntityManager is an interface in Java Persistence API (JPA) used for handling database operations. In this context, the error suggests that the application is unable to obtain a valid EntityManager instance.
• Actual Transaction: A transaction is a unit of work performed on a database that must be executed atomically (all or nothing). When performing operations like persist, update, or delete, JPA requires an active transaction. The error indicates that there is no active transaction associated with the current thread.
• Cannot reliably process ‘persist’ call: The persist() method in JPA is used to save a new entity into the database. Since there is no active transaction, it cannot guarantee the reliability of the persist operation.

To resolve this error, you need to ensure that you have a valid EntityManager and an active transaction. Here’s an example to illustrate how to fix this issue:

    
EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("your-persistence-unit");
EntityManager entityManager = entityManagerFactory.createEntityManager();

try {
    EntityTransaction transaction = entityManager.getTransaction();
    transaction.begin();

    // Perform database operations
    YourEntity entity = new YourEntity();
    entityManager.persist(entity);

    transaction.commit();
} catch(Exception e) {
    // Handle exception
    e.printStackTrace();
    entityManager.getTransaction().rollback();
} finally {
    entityManager.close();
    entityManagerFactory.close();
}
    
  

In the above example:

• The EntityManagerFactory is created using the persistence unit name defined in your persistence.xml file.
• An EntityManager is obtained from the EntityManagerFactory.
• A try-catch block is used to handle exceptions and ensure a proper transaction management.
• Before performing any database operations, begin() method is called on the EntityTransaction object to start the transaction.
• The persist() method is used to save the entity.
• If any exception occurs, the transaction is rolled back and the exception is handled accordingly.
• In the finally block, the EntityManager is closed to release resources.

By following this pattern, you ensure that a valid EntityManager is obtained, an active transaction is present, and the persist operation is reliable.