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Hibernate Criteria can't create joins for Embedded objects

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sayantan_sinha

Post subject: Hibernate Criteria can't create joins for Embedded objects

Posted: Fri Sep 16, 2011 7:33 am

Newbie

Joined: Fri Sep 16, 2011 7:13 am
Posts: 2

I believe many of you must be already knowing the usage of Embedded Class which we use to define composite primary keys in an Entity class. However, it seems Hibernate Criteria is not able to read joins if I'm using Embedded objects to refer to an Entity class.

Consider the following example:-

I’ve three tables A, B & AB, where AB holds relationship between A & B and hence has a composite primary key which comprises of the primary key of A & primary key of B. I represent the relationship in hibernate as below (i’m using annotations):-

Entity class A.java
——————–-------------

//imports…..
@Entity
@Table(name=”A”)
public class A{
private long aId;
….//other properties
private List bList; //I’ve deliberately given the name bList since using this I can get data of B.
@Id
@Column(name=”A_ID”)
public long getAId(){
return aId;
}
public void setAId(long aId){
this.aId = aId;
}
@OneToMany(mappedBy=”pk.a”)
public List getBList(){
return bList;
}
public void setBList(List bList){
this.bList = bList;
}
}

Entity class B.java
——————–——————–------

//imports…..
@Entity
@Table(name=”B”)
public class B{
private long bId;
private String name;
….//other properties
private List aList; //I’ve deliberately given the name bList since using this I can get data of A.
@Id
@Column(name=”B_ID”)
public long getBId(){
return bId;
}
public void setId(long bId){
this.bId = bId;
}
@Column(name=”B_NM”)
public String getName(){
return name;
}
public void setName(String name){
this.name = name;
}
@OneToMany(mappedBy=”pk.b”)
public List getAList(){
return aList;
}
public void setAList(List aList){
this.aList = aList;
}
}

Entity class AB.java
——————–——————–------

//imports…..
@Entity
@Table(name=”AB”)
public class AB{
private AB_pk pk;
….//other properties
//Constructor to set PK object
public AB(A a, B b){
pk = new AB_pk();
pk.setA(a);
pk.setB(b);
}
@EmbeddedId
public AB_pk getPk(){
return pk;
}
public void setPk(AB_pk pk){
this.pk = pk;
}
}

Embeddable class AB_pk.java
——————–——————–------

//imports…..
@Embeddable
public class AB{
private A a;
private B b;
public AB_pk(){ } //Empty constructor – required
@ManyToOne
@JoinColumn(name=”A_ID”)
public A getA(){
return a;
}
public void setA(A a){
this.a = a;
}
@ManyToOne
@JoinColumn(name=”B_ID”)
public B getB(){
return b;
}
public void setB(B b){
this.b = b;
}
}

Criteria code block
——————–——————–------

Criteria criteria = session.createCriteria(A.class);
criteria.createCriteria(“bList”, “ab”, CriteriaSpecification.INNER_JOIN);
criteria.createAlias(“ab.pk”, “pk”);
criteria.createCriteria(“pk.B”, “b”, CriteriaSpecification.INNER_JOIN);
ProjectionList projections = Projections.projectionList();
projections.add(Projections.property(“b.name”), “bName”);
criteria.setProjection(projections);
criteria.add(Restrictions.eq(“aId”, Long.valueOf(1)));
List list = criteria.list();

SQL Query formed by Hibernate
——————–——————–------

SELECT b.B_NM FROM A a INNER JOIN AB ab WHERE a.A_ID = 2733

If you notice that it’s able to identify B_NM column through the Embedded ID relationship in Projections but the inner join specified in Criteria wasn’t added by hibernate in the SQL query generated by itself.
Does anybody know where the problem is?

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sayantan_sinha

Post subject: Re: Hibernate Criteria can't create joins for Embedded objects

Posted: Mon Sep 19, 2011 1:52 am

Newbie

Joined: Fri Sep 16, 2011 7:13 am
Posts: 2

So, anybody can help on this? Is this possible to achieve in Hibernate Criteria?

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jactor

Post subject: Re: Hibernate Criteria can't create joins for Embedded objects

Posted: Thu Oct 13, 2011 8:24 am

Beginner

Joined: Sun Aug 13, 2006 8:40 am
Posts: 28

I have a similar problem.

I have a class

Code:

with an embedded class

Code:

which have some properties that is common for that type of class.

When I use this embedded class as a part of a restriction in a criteria search (ex:

Code:

org.hibernate.criterion.Restriction.in("b", Set<B>)

) I get an SqlException for an Illegal SQL. It seems that Hibernate is unable to generate a criteria for an embedded class when using

Code:

org.hibernate.criterion.Restriction.in

Is there another solution for this kind of problem.

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