I am trying to successfully map two classes in an OneToOne relationship; mainly because my User class needs two Ids that are GeneratedValue. I’ve used Lambook for getter setters and constructors ; I’m using postgres as database.

@Entity
@Table(name = "user")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)  
    private Long Id;

    @OneToOne(fetch = FetchType.LAZY,cascade = CascadeType.ALL)  
    @JoinColumn(name = "digital_code", referencedColumnName = "digital_code")  
    private DigitalCode digitalCode;  

    @Column (name = "name")  
    private String name;  
    @Column (name = "email")  
    private String email;
}

Second Class

@Entity public class DigitalCode {     
    @Id     
    @Column(name = "digital_code", unique = true, nullable = false)     
    @Size(min = 100000, max = 999999)     
    @GeneratedValue(strategy = GenerationType.IDENTITY)     
    private Long digitalCodeId; 
}

Both tables user and digital_code do get created in the database. However,
When I post data into my database with body

{     
    "name": "test name",     
    "email": "[email protected]", 
}

I get 200 back with

{   
    "digital_code": null,     
    "name": "test name",     
    "email": "[email protected]",     
    "id": 1
}

While I was expecting

{
    "digital_code": 100001, // due to @size annotation     
    "name": "test name",     
    "email": "[email protected]",     
    "id": 1
}