CODEWITHSUNDEEP
javahibernatejpajpa-2.0spring-data-jpa
brianbro
brianbro

Reputation: 4769

@ManyToMany JPA 2 complex query

I have got the following ManyToMany mapping.

@Entity
public class Class1 {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "class1_class2", joinColumns = @JoinColumn(name = "class1Id"),  inverseJoinColumns = @JoinColumn(name = "class2Id"))
private List<Class2> class2;
}

@Entity
public class Class2 {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
}

I want to retrieve all the Class1 entities, that have relation with Classe2 entities, with class2Id = 1 and class2Id =2 and class2Id =3. {1,2,3}

Or to filter the Classe1 entities that have on their class2 List, the Class2 entities with the values: class2Id = 1 and class2Id =2 and class2Id =3

For example:

If on the join table, i have got the follwoing values.

class1Id   class2Id
   1          1
   1          2
   1          3
   1          4
   6          1
   6          2
   6          3
   4          1
   5          2

The result would be for this example, Class1 with class1Id: 1 and 6. Because Class1 entity, with class1Id=1 has relaion with classe2Id: 1,2,3, 4 And Class1 entity, with class1Id=2 has relaion with classe2Id: 1,2,3

Is it possible to get the right entities returned with JPA2 (Predicate)?

And is there any better mappings to handle this case?

For the moment, i have come up with the following SQL query:

select v1.class1Id from class1_class2 v1
inner join class1_class2 v2 on v1.class1Id=v2.class1Id
inner join class1_class2 v3 on v2.class1Id=v3.class1Id
where v1.classe2Id=1 and v2.classe2Id=2 and v3.classe2Id=3;

Upvotes: 3

Views: 6287

Answers (3)

brianbro
brianbro

Reputation: 4769

Here is the query that can help:

select c1 
from Class1 c1 
join c1.class2 c2 
where c2.id in (1,2,3)
group by c1
having count(c1)=3 ;

Upvotes: 4

Oleksandr Bondarenko
Oleksandr Bondarenko

Reputation: 2018

At first in your class Class2 you'll need add the following:

@ManyToMany(fetch = FetchType.LAZY, mappedBy="class2")
private List<Class1> class1;

After this your task should be done with this query:

select c1 from Class1 c1 join c1.class2 c2 where c2.id in ?1 group by c1

where ?1 - object of type List<Long>, containing ids {1,2,3}.

Upvotes: 3

HRgiger
HRgiger

Reputation: 2790

Still some parts are not very clear on question as I dont see class1Id=2 in join table values or class1Id=6 has just class2Id=1. But anyway I will give you similar predicate mapping example so you can modify for your needs. I have used StaticMetaModels. You can move them to the same package of your entity classes. I was not able to test ofcourse but I believe can be a good roadmap.

JPA 2.0 query:

     CriteriaBuilder criteriaBuilder = getEm().getCriteriaBuilder();

     CriteriaQuery<Class1> criteriaQuery = criteriaBuilder.createQuery(Class1.class);

     Root<Class1> fromClass1 = criteriaQuery.from(Class1.class);

     List<Predicate> conditions = new ArrayList<Predicate>();

     Subquery<Class2> qry = criteriaQuery.subquery(Class2.class);                     

     Root<Class2> fromClass2 = qry.from(Class2.class);

     qry.select(fromClass2);

     qry.where(criteriaBuilder.equal(fromClass2.get(Class2_.getId()), idParamGoesHere));

     conditions.add(criteriaBuilder.in(.get(Class1_.getClass2()).value(qry));

     criteriaQuery.where(conditions.toArray(new Predicate[0]));

     TypedQuery<Class1> query = getEm().createQuery(criteriaQuery);

     List<Class1> results = query.getResultList();

StaticMetaModel Class1: (not needed for this case but i have added)

@StaticMetamodel(Class1.class)
public class Class1_ {

    private static volatile SingularAttribute<Class1, Long> id;
    private static volatile SingularAttribute<Class1, Class2> class2;

public static SingularAttribute<Class1, Long> getId() {
        return id;
    }
    public static void setId(SingularAttribute<Class1, Long> id) {
        Class1_.id = id;
    }
    public static SingularAttribute<Class1, Class2> getClass2() {
        return class2;
    }
    public static void setClass2(SingularAttribute<Class1, Class2> class2) {
        Class1_.class2 = class2;
    }
}

StaticMetaModel Class2:

@StaticMetamodel(Class2.class)
public class Class2_ {

    private static volatile SingularAttribute<Class2, Long> id;

public static SingularAttribute<Class2, Long> getId() {
        return id;
    }
    public static void setId(SingularAttribute<Class2, Long> id) {
        Class2_.id = id;
    }
}

Upvotes: 1

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