为什么我在定义时收到 IdClass 未定义错误？

Question

I have two classes, a User and a LocalUser. LocalUser uses a FK to User as it's PK. When I try to create a LocalUserRepository, I receive the exception: java.lang.IllegalArgumentException: This class [~.LocalUser] does not define an IdClass.

I have been searching for an answer for a few hours and everything I have tried has not worked.

@Entity( name = "User" )
@Table( name = "users" )
public class User implements Serializable
{
    @Id
    @GeneratedValue( strategy = GenerationType.IDENTITY, generator = "user_id_seq" )
    @Column( name = "id", updatable = false, columnDefinition = "BIGSERIAL" )
    private Long id;
    @Column( name = "given_name", nullable = false )
    private String givenName;
    @Column( name = "family_name" )
    private String familyName;
    @Enumerated( EnumType.STRING )
    @Column( name = "role", nullable = false, columnDefinition = "VARCHAR(32)" )
    private Role role;

    ...
}

---

@Entity( name = "LocalUser" )
@Table( name = "local_user" )
@IdClass( User.class )
public class LocalUser implements Serializable
{
    @Id
    @OneToOne( optional = false, orphanRemoval = true )
    @JoinColumn( name = "user_id", nullable = false, unique = true )
    private User user;
    @Column( name = "username", unique = true, nullable = false )
    private String username;
    @Column( name = "password", nullable = false )
    private String password;

    ...
}

---

public interface LocalUserRepo extends JpaRepository<LocalUser, User>
{
    @Query( "SELECT u.user FROM LocalUser u WHERE u.username = :username AND u.password = :password" )
    User getUser( String username, String password );
}

The desired result is two tables with matching this schema:

user

id [PK]	given_name	family_name	role
1	Example	User	User

local_user

user_id [PK,FK(user)]	username	password
1	exampleuser	########

Answer 1

After much searching, I finally managed to accomplish what I was attempting. I needed to add an id to LocalUser and map it to a user. Here is what I did:

@Entity
@Table( name = "local_users" )
public class LocalUser
{
    @Id
    @GeneratedValue( strategy = GenerationType.IDENTITY )
    @Column( name = "user_id", nullable = false )
    private Long id;

    @MapsId
    @OneToOne( fetch = FetchType.EAGER, optional = false )
    @JoinColumn( name = "user_id", nullable = false, foreignKey = @ForeignKey( name = "local_users_user_id_fk" ) )
    private User user;

    @Column( name = "password", nullable = false )
    private String password;

    @Column( name = "username", nullable = false, unique = true )
    private String username;
}

---

@Entity
@Table( name = "users" )
public class User
{
    @Id
    @GeneratedValue( strategy = GenerationType.IDENTITY, generator = "user_id_seq" )
    @Column( name = "id", updatable = false, columnDefinition = "BIGSERIAL" )
    private Long id;
    @Column( name = "given_name", nullable = false )
    private String givenName;
    @Column( name = "family_name" )
    private String familyName;
    @Enumerated( EnumType.STRING )
    @Column( name = "role", nullable = false, columnDefinition = "VARCHAR(32)" )
    private Role role;

    ...

}

---

@Repository
public interface LocalUserRepo extends JpaRepository<LocalUser, Long>
{
    @Query( "SELECT u.user FROM LocalUser u WHERE u.username = :username AND u.password = :password" )
    User getUser( String username, String password );
}