Java Hibernate @OneToMany Criteria Projections返回NULL

Question

I have One to many relationship Owner->Dog.

I am to query the dog by ID as well bring the Owner in EAGER way I have set this code using Hibernate 4.1.6 not XML mapping is used. i only need some fields from DOG and OWNER using Projections the SQL being generated by Hibernate is perfect but my objects is not being populate because DOG is returning the fields populated but owner is returned DOG.OWNER==NULL here is the code i am using so far... My entities.other code is omit by brevity

@Entity
public class Owner implements Serializable
{
    Set<Dog>dogs=new HashSet<Dogs>(0);
    @OneToMany(fetch=FetchType.LAZY, mappedBy="owner")
    public Set<Dogs> getDogs(){return this.dogs}    
}   

@Entity
public class Dog implements Serializable
{
    private Owner owner;    
    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn(name="ownerid")
    public Owner getOwner(){return this.owner;}
 }  

here is my method.

public Dog getDogAndOwnerById(Integer dogId) 
{
    Projection p=Projections.projectionList()
    .add(Projections.property("d.id"),"id")
       .add(Projections.property("o.id"),"id");//and others fields
    Session session = getHibernateTemplate().getSessionFactory().openSession();        
    Criteria like = session.createCriteria(Dog.class,"d")
    .add(Restrictions.idEq(dogId)).setProjection(p)
    .setResultTransformer(Transformers.aliasToBean(Dog.class))
    .setFetchMode("owner",FetchMode.JOIN).createAlias("owner","o");        
    Dog dog = (Dog)like.uniqueResult();        
    //Object[]obj=(Object[])like.uniqueResult(); for(Object id:obj)System.out.println(id);
    //System.out.println(obj.length);
    session.close();
    return dog;
    //dog is OK BUT dog.OWNER is null.
}    

the query is perfect here is the SQL

select
    this_.ID as y0_,
    owner_.ID as y1_ 
from
    dog this_ 
inner join
    owner owner_ 
        on this_.ownerid=owner_.ID 
where
    and this_.ID = ?    

my problem is... Dog instance is NOT null and all the fields are OK meanwhile Dog.Owner is returnig null I have try this not using any Transformers.

Object[]obj=(Object[])like.uniqueResult(); for(Object id:obj)System.out.println(id);
System.out.println(obj.length);

And I can see the data correct what Hibernate is not returning my objects right? What I am doing wrong.

any help is hugely appreciate.

[update] if i use this

Projection p=Projections.projectionList()
.add(Projections.property("d.id"),"id")
.add(Projections.property("o.status"),"status");

and status belongs to both tables the DOG entity is populate the other is not.

if i use

Projection p=Projections.projectionList()
.add(Projections.property("d.id"),"id")
.add(Projections.property("o.address"),"address");

and adress belong only to owner exception is thrown.

Exception in thread "main" org.hibernate.PropertyNotFoundException: 
Could not find setter for address on class com.generic.model.Dog

Seems that Hibernate ALWAYS return at maximun 1 entity populate they can't populate both tables[selected columns] into objects[selected objects]?

Answer 1

I wrote a ResultTransformer that can solve your problem. It's name is AliasToBeanNestedResultTransformer, check it out on github .

Answer 2

i follow this post Complex Hibernate Projections and as result i write my own Transformer because resultTransformer alias to bean in hibernate in one level deep.

here is my simple resultTransformer

public class MyOwnTransformer implements ResultTransformer
{
 @Override//the same order in projection list properties is the same returned by data array...  
 public Dog transformTuple(Object[]data,String[]alias)
 {return new Dog((Integer)data[0],new Owner((Integer)data[1]));} 
 @Override
 public List transformList(List dogs){return dogs;}//nothing to do here....
 }

and in my criteria i fix the code like this.

public Dog getDogAndOwnerById(Integer dogId) 
{
  Projection p=Projections.projectionList()
  .add(Projections.property("d.id"))//i dont need the alias anymore..
  .add(Projections.property("o.id"));
  Session session = getHibernateTemplate().getSessionFactory().openSession();        
  Criteria like = session.createCriteria(Dog.class,"d")
  .add(Restrictions.idEq(dogId)).setProjection(p)

  .setResultTransformer(new MyOwnTransformer())

  .setFetchMode("owner",FetchMode.JOIN).createAlias("owner","o");        
  Dog dog = (Dog)like.uniqueResult();        
  session.close();
  return dog;
}    

i hope it helps somebody.