I have two tables: users and userdetails as follows:

package com.example.easynotes.model;

import javax.persistence.*;
import java.io.Serializable;

@Entity
@Table(name = "users")
@IdClass(UserID.class)
public class User implements Serializable {

    @Id
    int id;

    @Id
    String name;

    String department;

    //getters and setters

}

The userdetails classes will be this:

public class UserDetails implements Serializable{

int id;

String name;

String address;

String otherFields;

//getters and setters

}

id and name in users is a composite primary and I want the same fields in userdetails to be the foreign key. How can I achieve this in hibernate ?

CodePudding user response：

We need to put both key in @Embeddable to detach compound key thenafter, put it in User Entity using @EmbeddedId and map both primary key using Hibernate Relational Mapping...

There are two option to Composite Primary Key:

1. Using @EmbeddedId
2. Using @IdClass()

Here down is example:

----------------------------------- Using EmbeddedId -----------------------------------

Compound primary key:

@Embeddable
public class UserIdName implements Serializable {
    int id;
    String name;
    
    // getter and setter
}

User:

@Entity
@Table(name = "users")
public class USER{
    @EmbeddedId
    private UserIdName id;

    String department;
    
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "user")
    private Set<Userdetail> userdetail;

    // getter and setter
}

UserDetails:

@Entity
@Table(name = "Userdetail")
public class Userdetail {

    @Id
    private int detail_id;

    @ManyToOne
    @JoinColumns({ @JoinColumn(name = "id", referencedColumnName = "id"),
            @JoinColumn(name = "name", referencedColumnName = "name") })
    private USER user;

    String address;

    String otherFields;

    // getter setter
}

----------------------------------- Using IdClass -----------------------------------

Compound primary key:

public class UserIdName implements Serializable {
    int id;
    String name;
    
    // getter and setter
}

User:

@Entity
@Table(name = "users")
@IdClass(UserIdName.class)
public class USER{
    @Id
    int id;

    @Id
    String name;

    String department;
    
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "user")
    private Set<Userdetail> userdetail;

    // getter and setter
}

UserDetails:

@Entity
@Table(name = "Userdetail")
public class Userdetail {

    @Id
    private int detail_id;

    @ManyToOne
    @JoinColumns({ @JoinColumn(name = "id", referencedColumnName = "id"),
            @JoinColumn(name = "name", referencedColumnName = "name") })
    private USER user;

    String address;

    String otherFields;

    // getter setter
}

-> If you wanna insert both foreign key manually try below code

Put this code in UserDetails

@ManyToOne
@JoinColumn(name = "id", referencedColumnName = "id", insertable = false, updatable = false)
@JoinColumn(name = "name", referencedColumnName = "name", insertable = false, updatable = false)
private USER user;

@Column(name="id")
private int id;

@Column(name="name")
private String name

// don't forget to put getter setter

User Table:

User Detail Table: