Using same entity twice in another entity in hibernate

Question

Let us say a class/entity named student which contains an id, father's occupation and mother's occupation and the entity classes are like this

Student class

@Entity
@Table(name = "student")
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true, updatable = false)
    private int id;

    @OneToOne
    @JoinColumn(name = "occupationId")
    Occupation fathersOccupation;

    @OneToOne
    @JoinColumn(name = "occupationId")
    Occupation mothersOccupation;

}

and the Occupation class

@Entity
@Table(name = "occupation")
public class Occupation {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "occupationId")
    int occupationId;

    @Column
    String title;

}

When I tried @OneToOne mapping for both father's occupation and mother's occupation it is throwing exception,Repeated column in mapping for entity. I tried adding @Column(name="<columnName>"), but it is not allowed. I really want those two fields,fathersOccupation and mothersOccupation with oneToOne mapping in the student table.

Abass A · Accepted Answer · 2017-06-15 20:08:56Z

5

@JoinColumn specify the name of the FK Column in your entity.

Your student entity have 2 FKs toward occupation, one for fathersOccupation and another one for mothersOccupation and you define mapping twice for the same. Ideally you should have fathers_occupation_id and mothers_occupation_id field in your student table and same attributes in your entity.

So you should put for each one the corresponding column name in your student table.

@JoinColumn(name ="fathers_occupation_id")
Occupation fathersOccupation;

@JoinColumn(name="mothers_occupation_id")
Occupation mothersOccupation;

edited Jun 15, 2017 at 20:08

answered Jun 15, 2017 at 20:00

Abass A

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Comments

Reni21 · Accepted Answer · 2019-07-03 14:02:19Z

3

If someone interesting in, the solution that worked for me was to rename mapping field in entity with @ManyToOne annotation and add prefix before "account_id":

@ManyToOne
@JoinColumn(name = "from_account_id") // add from_
private Account fromAcc;
@ManyToOne
@JoinColumn(name = "to_account_id") // add to_
private Account toAcc;

answered Jul 3, 2019 at 14:02

Reni21

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1 Comment

Gautam Tyagi Over a year ago

and what to mention in Account Entity for ManyToOne annotaion.

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