Hibernate JPA IdentifierGenerationException: null id generated for class with @embeddedid

Question

I am having trouble mapping my database domain model to the program entities in one case where the entity is essentially a join table (a period) which combines two other entities (a timeslot and a day). Another entity (a lesson) then has a reference to this period entity, determining when it occurs.

When I try to save a lesson with a new period using saveOrUpdate(lesson) hibernate throws an IdentifierGenerationException

org.hibernate.id.IdentifierGenerationException: null id generated for:class com.trials.domain.Period

The database looks like below (not the real database, just the key tables and columns)

enter image description here

In the java hibernate model, I have used an embedded id for the primary key of the period class and the lesson class then has a reference to a period.

Period.java

@Entity
@Table(name = "period")
public class Period{
    @EmbeddedId
    private PeriodId periodId;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "day_idday", nullable = false, insertable = false, updatable = false)
    private Day day;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "timeslot_idtimeslot", nullable = false, insertable = false, updatable = false)
    private Timeslot timeslot;

    //constructors, getters, setters, hashcode, and equals
}

And the embedded id just has the primary key columns:

PeriodId.java

@Embeddable
public class PeriodId implements Serializable {
    @Column(name = "timeslot_idtimeslot")
    private int timeslotId;

    @Column(name = "day_idday")
    private int dayId;

    //constructors, getters, setters, hashcode, and equals
}

Then there is the lesson class that uses the period defined as:

Lesson.java

@Entity
@Table(name = "lesson")
public class Lesson {
    @Id
    @Column(name = "idlesson")
    private int lessonId;

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumns({@JoinColumn(name = "period_timeslot_idtimeslot", nullable = false, updatable = false), @JoinColumn(name = "period_day_idday", nullable = false, updatable = false)})
    private Period period;
    //constructors, getters, setters, hashcode, and equals
}

The Timeslot and Day entity classes are both very basic pojos, and their ids use GenerationType.AUTO. So my problems are:

What causes this IdentifierGenerationException
How to avoid it while keeping the same database model

Thanks in advance

possible duplicate of NULL ID Generated Via @GeneratedValue On Composite Key Using @EmbeddedId — Xstian
– Xstian, Commented Aug 13, 2014 at 20:26
@Xstian I have read many SO questions on similar issues including that question answer and it is NOT like my problem. I am not manually managing any keys, just using an embedded id in a way that at first seemed straight forward — Japheth Ongeri - inkalimeva
– Japheth Ongeri - inkalimeva, Commented Aug 14, 2014 at 7:26

Dalton · Accepted Answer · 2014-08-13 23:15:34Z

10

Put those guys

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "day_idday", nullable = false, insertable = false, updatable = false)
private Day day;

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "timeslot_idtimeslot", nullable = false, insertable = false, updatable = false)
private Timeslot timeslot;

inside the PeriodId class and throw away those ints. I have done a mapping similar to yours this way and it works.

answered Aug 13, 2014 at 23:15

Dalton

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4 Comments

Japheth Ongeri - inkalimeva Over a year ago

OK, I did this in the PeriodId class and marked the original properties @transient in the Period class. Then delegated the getters and setters in the period class to set and fetch their values from the embedded periodId

Daniel Vilas-Boas Over a year ago

I tried your approach but now im getting Data truncation: Data too long for column 'dalekComponent' at row 1.

Mohammed Idris Over a year ago

Could you please explain what you mean by "throw away those ints"? Do I keep the Timeslot and Day in Lesson and remove the int Ids in PeriodId? What is the way to use @Transient?which property will be transient if I move them to PeriodId?

Dalton Over a year ago

@MohammedIdris The ints that are int the original post.

Petr Osipov · Accepted Answer · 2015-03-06 18:13:32Z

I was able to create the following mapping for my case (scala code) and could totally throw away the @Embeddable class:

@Entity
@Table(name = "payment_order_item", schema = "pg")
@IdClass(classOf[PaymentOrderItem])
final class PaymentOrderItem extends Serializable{

  @Id
  @ManyToOne
  @JoinColumn(name = "order_item_id", referencedColumnName = "id")
  var orderItem: OrderItem = _

  @Id
  @ManyToOne
  @JoinColumn(name = "payment_id", referencedColumnName = "id")
  var payment: Payment = _
}

So the following should work for you then

@Entity
@Table(name = "period")
@IdClass(Period.class)
public class Period extends Serializable{

    @Id
    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "day_idday", referencedColumnName = "id", nullable = false)
    private Day day;

    @Id
    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "timeslot_idtimeslot", referencedColumnName = "id", nullable = false)
    private Timeslot timeslot;

    //constructors, getters, setters, hashcode, and equals
}

Rowanto · Accepted Answer · 2014-08-13 22:58:10Z

0

On a first glance, You're missing the generated value annotation in the embedded id class.

@Embeddable
public class PeriodId implements Serializable {

    @GeneratedValue
    @Column(name = "timeslot_idtimeslot")
    private int timeslotId;

    @GeneratedValue    
    @Column(name = "day_idday")
    private int dayId;

    //constructors, getters, setters, hashcode, and equals
}

answered Aug 13, 2014 at 22:58

Rowanto

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