CODEWITHSUNDEEP
javahibernatejpaorm
Daud
Daud

Reputation: 7887

Why does this one-to-many mapping fails when using mappedBy?

@Entity
public class Person implements Serializable{

    @Id
    @GeneratedValue
    private int id;
    private String name;

    @OneToMany(cascade = CascadeType.ALL, mappedBy = "person")
    private List<Car> cars;

        //getters and setters
}


@Entity
public class Car implements Serializable{
    @Id
    @GeneratedValue
    private int id;
    private String name;

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

        // getters and setters
}

And.. I use it thus..

       Person per = new Person();
    per.setName("some");

    Car car1 = new Car();
    car1.setName("Ford");

    Car car2 = new Car();
    car2.setName("WagonR");

    //s.save(car1);
    //s.save(car2);
    per.setCars(new ArrayList<Car>());
    per.getCars().add(car1);
    per.getCars().add(car2);

    s.save(per);

Now.. the table Car has a column person_id but its showing null for both the cars.. what am I doing wrong here ? The table Person is correctly being filled. If I remove the "mappedBy" from the Person table.. and instead include the @JoinColumn here... then it works fine.

Upvotes: 0

Views: 193

Answers (2)

overmeulen
overmeulen

Reputation: 1158

With your mapping, the owner of the relation is the Car and not the Person ... That's why when saving the Person, the Car is not saved. If you remove the mappedBy then the owner of the relation becomes the Person and you get your expected behavior!

Upvotes: 1

Derek
Derek

Reputation: 749

Try calling car.setPerson(per).

Upvotes: 1

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