Best Way To Get Aggregate Function Result Inside The Entity Object

Many time I have to get the SQL aggregate query result inside the Entity Object itself. As of now I could able to achive the same by the following code CriteriaBuilder cb = em.

Solution 1:

If you cannot use @Formula then I'd suggest create a database view basic on your select and mapping an additional entity to that. You can then map this to your existing entity using either as a @OneToOne or by using @SecondaryTable.

This has the added advantage of being JPA compliant (i.e. not using Hibernate's propreitary @Formula) and would look something like:

@Entity@Table(name = "test")
public class Test {
    @Id@Column(name = "id")
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    @Column(name = "name")
    private String name;

    @Column(name = "type")
    private Integer type = 0;

    @OneToOne//or via secondary table
    private TestSummaryInfo summaryInfo;

    publiclonggetQuantity(){
        returnsummaryInfo.getQuantity();
    }
}

Summary mapped to a view:

@Entity@Table(name = "vw_test_summary")
public class TestSummaryInfo {
    @Id@Column(name = "id")
    private Integer id;

    @Column(name = "quantity")
    private Long quantity;
}