Spring Data JPA joining two or more entites - mysql

Question

I have three entities,
#Entity
public class Deck {
#Id
private int id;
private int number;
private String name;
#OneToMany(mappedBy = "deck")
private Set<Lab> labs;
//getter and setter methods
}
#Entity
public class Lab {
#Id
private int id;
private String name;
#ManyToOne
private Deck deck;
#OneToMany(mappedBy = "lab")
private Set<LabBooking> labBooking;
//getter and setter methods
}
#Entity
public class LabBooking {
#Id
private int id;
private Date startTime;
private Date endTime;
#ManyToOne
private Lab lab;
//getter and setter methods
}
Following is the LabRepository,
public interface LabRepository extends CrudRepository<Lab, Integer>{
#Query("SELECT l FROM Lab l JOIN l.labBooking lb WHERE l.deck.id = :deckId AND lb.startTime > '2016-02-24 15:00:00'")
List<Lab> findLabs(#Param("deckId") int deckId);
}
I am trying to retrieve the list of Labs in a deck which are occupied from a particular time.
When I execute the equivalent query (SELECT * FROM lab l JOIN lab_book lb ON l.id = lb.lab_id WHERE l.deck_id = 9999 AND lb.start_time > '2016-02-24 15:00:00') in MySQL, I am getting the following result
id name deck_id id end_time start_time lab_id
9001 Lab One 9999 5 2016-02-24 17:00:00 2016-02-24 16:00:00 9001
In the spring application I am getting the following result,
[{
"lab_id": 9001,
"lab_name": "Lab One",
"lab_booking": [{
"id": 4,
"start_time": "2016-02-24 15:00:00",
"end_time": "2016-02-24 16:00:00"
}, {
"id": 5,
"start_time": "2016-02-24 16:00:00",
"end_time": "2016-02-24 17:00:00"
}, {
"id": 3,
"start_time": "2016-02-24 14:00:00",
"end_time": "2016-02-23 14:30:00"
}]
}]
The Lab object was supposed to contain only the booking id 5, instead it shows all the ids.
If the sql query return 5 records, then the repository returns 5 Lab objects which are duplicate. What may be the issue?

Answer 1

Seems that your missing distinct.
SELECT distinct l FROM Lab l JOIN l.labBooking lb WHERE l.deck.id = :deckId AND lb.startTime > '2016-02-24 15:00:00'"