How to @joincolumn key from table a with foreign key in table b in JPA/Spring

how do I link via @joincolumn an already existing key from table A with a field in table B.

In detail I have a class server with its key serverId. It has a one-to-one relation to a class license linked by the serverId from the embedded Class LicenseKey. Now the problem is, that my serverId is already defined as a ID and I got the error:

org.hibernate.MappingException: Column 'serverId' is duplicated in mapping for entity 'com.example.jpa.model.Server' (use '@Column(insertable=false, updatable=false)' when mapping multiple properties to the same column)

import jakarta.persistence.*;

@Entity
@Table(name = "server")
public class Server {

@Id
private String serverId;

 @OneToOne
    @JoinColumn(name="version", referencedColumnName="version")
    @JoinColumn(name="serverId", referencedColumnName="serverId")
    private License license;
    
    // getter and setter    
}


@Entity
@Table(name = "license")
public class License {

    @EmbeddedId
    private LicenseKey id;
  // ...
}



@Embeddable
public class LicenseKey implements Serializable  {
    String version;
    String serverId;
 // ...
}

After that I tried to use @JoinColumn(name="serverId", insertable=false, updateable=false, referencedColumnName="serverId") but it does not work and I got more errors. Maybe it is easy and someone can help me here....

Solution

This might resolve your issue.

LicenseKey

@Embeddable
@Getter
@Setter
public class LicenseKey implements Serializable {

   private Long l_server_id;

   //
}

License

    @Entity
    @Getter
    @Setter
    public class License {
    
        @EmbeddedId
        private LicenseKey licenseKey;
    
        @OneToOne
@JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
        @MapsId("l_server_id")
        private Server server;
    
    }

Server

 @Entity
    @Getter
    @Setter
    public class Server {
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long serverId;
    
        private String serverName;
    
            @OneToOne(cascade = CascadeType.ALL,mappedBy = "server",fetch = FetchType.EAGER)
        private License license;
    
    }

This is going to create the table structure like this

Hibernate: create table license (l_server_id bigint not null, primary key (l_server_id)) engine=InnoDB
Hibernate: create table server (server_id bigint not null auto_increment, server_name varchar(255), primary key (server_id)) engine=InnoDB
Hibernate: alter table license add constraint FKkope30d18c3etsmqjipi6yrw9 foreign key (l_server_id) references server (server_id)