Question

Usually, Play! commits the transaction after a request completes successfully.
What is the correct way to commit a transaction manually in Play?

void addPerson() {
  Person p = new Person("John", "Doe");
  p.save();

  // TODO - commit the transaction

  // Now p should have an ID
  assert p.id != null;
  usePersonIdForSomethingNasty(p.id);
}

Answer 1

You can get the Hibernate EntityManager by calling JPA.em(). Then, from there, you have access to the transaction (JPA.em().getTransaction()).

If you intend to manage the transaction yourself, you will want to disable Play!’s transaction handling (there is a @NoTransaction annotation you can use on the method or controller to do that). Otherwise, Play! will try to commit the transaction at the end of the request anyway, and if you have already done that yourself, that will cause an exception.