也许这是一个过于简单的问题，但是当我尝试删除用户实体时却出现了异常。

用户实体：

@Entity
@Table(name = "users")
public class User 
{
    @Transient
    private static final int SALT_LENGTH = 32;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;

    @NotNull
    private String firstName;

    @NotNull
    private String lastName;

    @Column(unique = true, length = 254)
    @NotNull
    private String email;

    // BCrypt outputs 60 character results.
    @Column(length = 60)
    private String hashedPassword;

    @NotNull
    private String salt;

    private boolean enabled;

    @CreationTimestamp
    @Temporal(TemporalType.TIMESTAMP)
    @Column(updatable = false)
    private Date createdDate;

我有一个实体类，该实体类使用外键引用用户。我想发生的是，当删除用户时PasswordResetToken，引用该用户的所有对象也会被删除。我怎样才能做到这一点？

@Entity
@Table(name = "password_reset_tokens")
public class PasswordResetToken 
{
    private static final int EXPIRATION_TIME = 1; // In minutes

    private static final int RESET_CODE_LENGTH = 10;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;

    private String token;

    @OneToOne(targetEntity = User.class, fetch = FetchType.EAGER)
    @JoinColumn(nullable = false, name = "userId")
    private User user;

    private Date expirationDate;

我正在将异常归结为 Cannot delete or update a parent row: a foreign key constraint fails (heroku_bc5bfe73a752182.password_reset_tokens, CONSTRAINTFKk3ndxg5xp6v7wd4gjyusp15gqFOREIGN KEY (user_id) REFERENCESusers(id))

我想避免PasswordResetToken在父实体中添加对的引用，因为User无需了解PasswordResetToken。