Question

the class rideSingle is always saved multiple times into the db if a OneToMany relationship is set to eager:

The class which is saved

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public class RideSingle  extends HibernateBasicClass{
    @OneToMany(mappedBy = "rideSingle", fetch = FetchType.EAGER)
    @Cascade(CascadeType.ALL)
    protected List<TimedRouteLocation> route;
}

The refered class:

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public class TimedRouteLocation  extends HibernateBasicClass {

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(nullable = false)
    protected RideSingle rideSingle;
}

the hibernate base class

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class HibernateBasicClass implements Serializable {
    private static final long serialVersionUID = -2253382207065396453L;

    @Id
    @SequenceGenerator(name = "generator", allocationSize = 1, initialValue = 1)
    @GeneratedValue(strategy = GenerationType.TABLE, generator = "generator")
    @JsonProperty
    private Long id;

    @Column(nullable = false)
    @Temporal(TemporalType.TIMESTAMP)
    private Date createdOn = new Date();

    @Version
    private Date lastModified;

    public HibernateBasicClass() {
        super();
    }

    public Long getId() {
        return id;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        final HibernateBasicClass objWId = (HibernateBasicClass) obj;
        // same id instance
        if (getId() == objWId.getId())
            ;
        // same id content
        if (getId() != null) {
            return getId().equals(objWId.getId());
        } else {
            return false;
        }
    }

}

There is just one variable, which then is saved by

    int i = rideSingleDaox.findAll().size(); // i is 0
    rideSingleDao.saveOrUpdate(this);
    i = rideSingleDaox.findAll().size(); // i is 2

The Dao looks like this:

public T saveOrUpdate(T object) {
    getSession().saveOrUpdate(object);
            return object;
}

If the rideSingle.route has 2 elements -> rideSingle is put twice in the db. If route has 3 elements, 3 copies of rideSingle are put in the database…

If rideSingle loads the route lazy, this problem does not occure.

@Entity
public class RideSingle {
    @OneToMany(mappedBy = "rideSingle", fetch = FetchType.EAGER)
    @Cascade(CascadeType.ALL)
    protected List<TimedRouteLocation> route;
}

Does anybody know why this is the case and how i could solve it?

Thanks a lot!

Answer 1

It is only a guess:

Try to implement a equals method for both classes.