createNativeQuery mapping to POJO (non-entity)

Question

I have an easy problem at the first glance:

entityManager()
.createNativeQuery("select count(*) as total, select sum(field) as total_sum ... blabla") 

And I want to write select result into POJO, like this:

public class AggregateStatsDto {

    private int total;

    private long totalSum;

    // getters, setters, cosntructors
}

What the best way to achieve this?

I can use JPA 2.1 and tried to use @SqlResultSetMapping in conjuction with @ConstructorResult:

@SqlResultSetMapping(name = "AggregateStatsResult", classes = {
        @ConstructorResult(targetClass = AggregateStatsDto.class,
                columns = {
                        @ColumnResult(name = "total"),
                        @ColumnResult(name = "totalSum")
                })
})
public class AggregateStatsDto {

        private long total;

        private int totalSum;

        // getters, setters, cosntructors
    }

Query:

AggregateStatsDto result = (AggregateStatsDto) entityManager()
    .createNativeQuery("select count(*) as total, select sum(field) as total_sum ... blabla", "AggregateStatsResult")
    .getSingleResult();

But no luck. It seems that it wants @Entity anyway. But I want just a POJO.

org.hibernate.MappingException: Unknown SqlResultSetMapping [AggregateStatsResult]"

Thanks in advance!

Answer 1

Put your @SqlResultSetMapping annotation in a class which is an actual entity, not in the DTO Class. Your entity manager can not discover your mapping when you annotate a SqlResultSetMapping in a non-entity.

@SqlResultSetMapping(name = "AggregateStatsResult", classes = {
    @ConstructorResult(targetClass = AggregateStatsDto.class,
            columns = {
                    @ColumnResult(name = "total"),
                    @ColumnResult(name = "totalSum")
            })
})
@Entity
public class SomeOtherClassWhichIsAnEntity {