JPA NamedQuery get distinct column - jpa

Question

I want to get an list of distinct City's from my User table. I thought the code below would work but gives an error:
User.java
#Entity
#Table(name="user_info")
...
#NamedQuery(name = "User.all.cities", query = "SELECT distinct u.city FROM User u"),
...
#embedded
private City city;
UserBusinessLogic.java:
...
TypedQuery<City> typedQuery = entityManager.createNamedQuery("User.all.cities",User.class);
List<City> names = typedQuery.getResultList();
...
It gives: type mismatch can not convert List to List. I tried two get first user then on getResult a City but same error one line below.
I see some examples but not really tell how to get it with correct code just the SQL syntax.
Thanks for your help
Jess

Answer 1

The first thing which doesn't look good is that you ask for City objects but declare to get User's.
You have:
#NamedQuery(name = "User.all.cities",
query = "SELECT distinct u.city FROM User u"),
TypedQuery<City> typedQuery =
entityManager.createNamedQuery("User.all.cities", User.class);
Where it should be:
TypedQuery<City> typedQuery =
entityManager.createNamedQuery("User.all.cities", City.class);

Answer 2

The code that works is:
results = getJpaTemplate().execute(new JpaCallback<List<City>>() {
#Override
public List<City> doInJpa(EntityManager em) throws PersistenceException {
TypedQuery<City> query = em.createNamedQuery("User.all.cities", City.class);
return query.getResultList() ;
}
}) ;