Question

Is there a way in JPA to convert random select clause values using createNativeQuery to a domain object. The domain object is not managed

I have the following sql query

select name, count(*) as cnt, sum(average_events)/count(*) as avg_events from (complex subquery)

I want to convert the values a,b,c into a domain object with three instance variables a, b and c. This domain object is not managed by JPA and hence does not have @Entity and no corresponding table.

Currently I am doing the following, which returns a list of objects.

 Query query = objectManager.getEntityManager().createNativeQuery(sqlStr);
 List resultList = query.getResultList();

Answer 1

Use this syntax:

SELECT new foo.MyCustomObject(a, b, c) FROM ...

Where MyCustomObject is any class with matching consdtructor:

public class MyCustomObject {
  private final String name;
  private final int cnt;
  private final float avg;
  public MyCustomObject(String name, int cnt, float avg) {
    this.name = name;
    this.cnt = cnt;
    this.avg = avg;
  }
  //...getters
}

Scala bonus: equivalent class:

class MyCustomObject(name: String, cnt: Int, avg: Float)
//no, actually that's it