与不同实体的单向@OneToOne 关系

Question

I have a User class:

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class User implements UserDetails {
    @Id
    @GeneratedValue
    Long id;

    @NotBlank
    private String name;
    @NotBlank
    private String password;

    private List<String> roles = new ArrayList<>();


    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return this.roles.stream().map(SimpleGrantedAuthority::new).collect(toList());
    }

    @Override
    public String getUsername() {
        return null;
    }

    @Override
    public boolean isAccountNonExpired() {
        return false;
    }

    @Override
    public boolean isAccountNonLocked() {
        return false;
    }

    @Override
    public boolean isCredentialsNonExpired() {
        return false;
    }

    @Override
    public boolean isEnabled() {
        return false;
    }
}

that models an user account that could be for a Student or a Teacher . They can own only one account so to specify this relationship I thought to model it by a @OneToOne relationship but I'm having trouble understanding if it would be a good idea to make that unidirectional.

Also, the User class could refer both to a Student and a Teacher by logic, what if I need to retrieve the details of the user starting from its User account? From my understanding, I should create a bi-directional relationship, but, which entity do I need to put inside the User class?

Answer 1

You can use an enumeration:

public enum UserType {
    STUDENT("Student"),
    TEACHER("Teacher");


    private final String displayValue;

    UserType(String displayValue) {
        this.displayValue = displayValue;
    }
    public String getDisplayValue() {
        return displayValue;
    }
}

And in your user entity:

@Entity
@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class User implements UserDetails {
    @Id
    @GeneratedValue
    Long id;

    @NotBlank
    private String name;
    @NotBlank
    private String password;

    private List<String> roles = new ArrayList<>();

    @Enumerated(EnumType.STRING)
    private UserType userType;


    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        return this.roles.stream().map(SimpleGrantedAuthority::new).collect(toList());
    }

    @Override
    public String getUsername() {
        return null;
    }

    @Override
    public boolean isAccountNonExpired() {
        return false;
    }

    @Override
    public boolean isAccountNonLocked() {
        return false;
    }

    @Override
    public boolean isCredentialsNonExpired() {
        return false;
    }

    @Override
    public boolean isEnabled() {
        return false;
    }
}