Implementing JPA query in Play for Scala

Question

I'm trying to implement JPA in Play for Scala, following these examples documented in Java.

In the following code I get a compilation error in jpaApi.withTransaction:

class ManageBanks @Inject() (jpaApi: JPAApi) extends Controller {

   @Transactional
   def readMany = {
      val em = jpaApi.em

      jpaApi.withTransaction( em -> {   //  <-- error in this line
          val query = em.createQuery("from BankHib order by name")
          val list = query.getResultList.asScala.toList.map(_.asInstanceOf[BankHib])
          list
      })
   }
}

The error:

overloaded method value withTransaction with alternatives: (x$1: Runnable)Unit [T](x$1: java.util.function.Supplier[T])T [T](x$1: java.util.function.Function[javax.persistence.EntityManager,T])T cannot be applied to ((javax.persistence.EntityManager, List[admin.manage.BankHib]))

What's wrong with this code?

Answer 1

Lambdas in Scala use syntax

em => ...

instead of

em -> ...

in Java.

-> in Scala is for maps.