CODEWITHSUNDEEP
javahibernatejpa
Chiu
Chiu

Reputation: 350

JoinColumn to an foreign key

I'm trying to achieve this with hibernate: table relationship

My codes is as follows:

Device model

@Entity
public class Device {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(nullable = false)
private long id;

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "fk_user", nullable = true, referencedColumnName = "ID")
private User user;
...
}

Statistics model

@Entity
public class Statistic {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(nullable = false)
private long id;

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumns({ @JoinColumn(name = "fk_device", nullable = false, referencedColumnName = "ID"),
        @JoinColumn(name = "fk_device_user", nullable = false, referencedColumnName = "fk_user") })
private Device device;
...
}

However, there's an error saying there's no logical column fk_user in device.

Caused by: org.hibernate.MappingException: Unable to find column with logical name: fk_user in device

I suppose it is because fk_user is a foreign key. But how can I solve this? Thanks.

Upvotes: 2

Views: 4082

Answers (1)

Maciej Kowalski
Maciej Kowalski

Reputation: 26492

Based on you schema i would map the Device entity as follows:

public class Devince{

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "user_id", nullable = true)
  private User user;
  ...
  }

}

You dont need the referencedColumnName as you are referring to the User entity primary key. If you would refer to non-primary key column, then that would be necessary.

Regarding the Statistic entity:

public class Statistic {
  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumns({ @JoinColumn(name = "device_id", nullable = false),
        @JoinColumn(name = "device_user_id", nullable = false, 
  referencedColumnName = "user_id") })
  ...
  }
}

Again, you only need the referencesColumnName in the second @JoinColumn.

Upvotes: 2

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