java - Complex Hibernate Projections

Question

I want to ask, it is possible that I create query projections and criterion for more than one level deep? I have 2 model classes:

@Entity  
@Table(name = "person")  
public class Person implements Serializable {
    @Id
    @GeneratedValue
    private int personID;
    private double valueDouble;
    private int valueInt;
    private String name;
    @OneToOne(cascade = {CascadeType.ALL}, orphanRemoval = true)
    @JoinColumn(name="wifeId")
    private Wife wife;
       /*   
        *  Setter Getter    
        */
}


@Entity 
@Table(name = "wife")  
public class Wife implements Serializable {

    @Id
    @GeneratedValue     
    @Column(name="wifeId")
    private int id;
    @Column(name="name")
    private String name;
    @Column(name="age")
    private int age;            
    /*
     *  Setter Getter
     */       
}

My Criteria API :

ProjectionList projections = Projections.projectionList(); 
projections.add(Projections.property("this.personID"), "personID");
projections.add(Projections.property("this.wife"), "wife");
projections.add(Projections.property("this.wife.name"), "wife.name");

Criteria criteria = null; 
criteria = getHandlerSession().createCriteria(Person.class); 
criteria.createCriteria("wife", "wife", JoinType.LEFT.ordinal()); 
criterion = Restrictions.eq("wife.age", 19);  
criteria.add(criterion); 
criteria.setProjection(projections);
criteria.setResultTransformer(Transformers.aliasToBean(Person.class)); 
return criteria.list();

and I hope, I can query Person, with specified criteria for wife property, and specified return resultSet. so i used Projections for getting specified return resultSet

I want personID, name(Person), name(Wife) will returned. how API i must Use, i more prefer use Hibernate Criteria API.

This time, I used code above for getting my expected result, but it will throw Exception with error message : Exception in thread "main" org.hibernate.QueryException: could not resolve property: wife.name of: maladzan.model.Person, and whether my Restrictions.eq("wife.age", 19); is correct for getting person which has wife with 19 as her age value ?

Thanks

Answer 1

AFAIK it is not possible to project more than one level deep with aliastobean transformer. Your options are

• create a flattened Data Transfer Object (DTO)
• fill the resulting Person in memory yourself
• implement your own resulttransformer (similar to option 2)

option 1 looks like this:

Criteria criteria = getHandlerSession().createCriteria(Person.class)
    .createAlias("wife", "wife", JoinType.LEFT.ordinal())
    .add(Restrictions.eq("wife.age", 19)); 
    .setProjection(Projections.projectionList()
        .add(Projections.property("personID"), "personID")
        .add(Projections.property("name"), "personName")
        .add(Projections.property("wife.name"), "wifeName"));
    .setResultTransformer(Transformers.aliasToBean(PersonWifeDto.class));

return criteria.list();