CODEWITHSUNDEEP
javahibernatespring-data-jpajpql
xmen-5
xmen-5

Reputation: 1906

HQL query in oneToMany relation

We have two Entities, Person and House.

One Person can have Many House.

I'm trying to write an HQL query that get the list of Person ordered by the size of the list of House, with one condition, that the value of the House should be greater than 400.

My class Person

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

        @OneToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE}, mappedBy = 
        "person", fetch = FetchType.LAZY)
        private List<House> houses = new ArrayList<>();

    /**
     * utility method to adjust relation
     * @param house
     */
    public void addHouse( House house ) {
        this.houses.add(house);
        house.setPerson(this);
    }
       //constructors, getters and setter omitted..
    }

My class House

@Entity
public class House {

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

    @ManyToOne
    @JoinColumn(name = "person_id")
    private Person person;

   //constructors, getters and setters omitted..
}

My tables representation on the database Layer

Person                     House
id name                    id   value  person_id
1  George                  1    500     1
2  Frederic                2    250     2
3  Jamal                   3    500     3
                           4    600     3

The result of my query should be [Jamal, George], and Frederic should not be included because the only house he has, doesn't have a value >400.

My query

public interface PersonRepository  extends JpaRepository<Person, Long> {

      @Query(value = "select p from Person p order by p.houses.size desc ")
      List<Person> getPersonWithMaxHouse();
}

with that, I'm getting an ordered list of persons based on the number of houses. How could I add the condition of the value of the House.

My second question is about the Sprig Data JPA Query equivalent of the hql I'm looking?

For example this repository query return all the persons whose names is equal to the given String : List<Person> findAllByName(String Name);

Upvotes: 1

Views: 802

Answers (1)

Michiel Leegwater
Michiel Leegwater

Reputation: 1180

I think it should be

public interface PersonRepository  extends JpaRepository<Person, Long> {

      @Query(value = "select distinct p from Person p join p.houses h where h.value > 400 order by p.houses.size desc ")
      List<Person> getPersonWithMaxHouse();
}

Upvotes: 2

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