java.lang.IllegalStateException: Session/EntityManager is closed

1

I have a rest api service that implements RealmResourceProvider, RealmResourceProviderFactory interface. It works correctly without a problem. However, I also need to access to the h2 database. Then when I add EntityManager as the class member, accessing through curl command, following error is thrown.

Caused by: java.lang.IllegalStateException: Session/EntityManager is closed
	at org.hibernate.internal.AbstractSharedSessionContract.checkOpen(AbstractSharedSessionContract.java:475)
	at org.hibernate.engine.spi.SharedSessionContractImplementor.checkOpen(SharedSessionContractImplementor.java:187)
	at org.hibernate.internal.SessionImpl.find(SessionImpl.java:2415)
	at org.hibernate.internal.SessionImpl.find(SessionImpl.java:2400)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at org.keycloak.connections.jpa.PersistenceExceptionConverter.invoke(PersistenceExceptionConverter.java:66)
	... 13 more

The way I use EntityManager is

@Path("/realms/{realm}/")
public class MyRest {
      @PersistenceContext(unitName = "keycloak-default")
      EntityManager em;
      public MyRest() {
          this.em = session.getProvider(JpaConnectionProvider.class).getEntityManager();
      }

      @Path("service/myendpoint")
      @POST
      @Consumes({MediaType.APPLICATION_JSON})
      @Produces({MediaType.APPLICATION_JSON})
      public Response myendpoint(final MyData data) {
          String id = UUID.randomUUID().toString();
          UserEntity user = this.em.find(UserEntity.class, id); 
          // some operation set user entity data
         this.em.persistent(user);
         user = this.em.find(UserEntity.class, id); // the operation fails because entity manager is closed
          ...
      }
}

I read this link. It recommends not placing eneitymanager in provider. And I consults the jpa example. I attempted to follow the example, but MyRestProvider class can not implement UserStorageProvider, because it has already implemented RelmResourceProvider.

How should I use EntityManager to prevent this EntityManager is closed problem? Thanks

2

Ok. Switching to this example fixes my problem. The example contains the usage with the combination of RESTful APIs, JPA throuh SPI. Thanks