Spring无法添加外键约束@​​ManyToOne

Question

我已尝试制作此实体：

@Entity
@Table(name = "rate")
public class Rate {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "rate_id")
    private Long id;

    @ManyToOne
    @JoinColumn(name = "user_id")
    private User answerer;

    @ManyToOne
    @JoinColumn(name = "answer_id")
    private Answer answer;

    @Column(name = "rate_rate")
    private Integer rate = AnswerConstants.MAX_RATE;
    //pluss getter-setters
}

不幸的是，我收到了这个错误：

  

引起：org.hibernate.tool.schema.spi.SchemaManagementException：无法对JDBC目标执行模式管理[alter table rate add constraint FK8totaejp8tp48clsoikn05fn2 foreign key（answer_id）reference answers（answer_id）]

我用Google搜索了大约一个小时但我找不到解决方案。你能帮助我吗？我为什么要这个？

另外：spring.jpa.hibernate.ddl-auto = update，如果我关闭它，它解决了问题，但我不想这样做只是因为这个。

Answer类看起来像这样：

@Entity
@Table(name = "answer")
public class Answer {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "answer_id")
    private Long id;

    @Column(name = "answer_text")
    @NotEmpty
    private String answerText;

    @ManyToOne
    @JoinColumn(name = "user_id")
    private User answerCreator;

    @ManyToOne
    @JoinColumn(name = "question_id")
    private Question question;

    @Column(name = "answer_creation_date")
    @NotNull
    private Date creationDate = new Date();

    @Column(name = "answer_rate")
    private Long answerRate = 1l;
    //plus getters-setters
}

用户类：

@Entity
@Table(name = "user")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "user_id")
    private Long id;
    @Column(name = "email")
    @Email(message = "*Please provide a valid Email")
    @NotEmpty(message = "*Please provide an email")
    private String email;
    @Column(name = "password")
    @Length(min = 5, message = "*Your password must have at least 5 characters")
    @NotEmpty(message = "*Please provide your password")
    @Transient
    private String password;
    @Column(name = "active")
    private int active;
    @ManyToMany()
    @JoinTable(name = "user_role", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "role_id"))
    private Set<Role> roles;
    //Plus getters-setters
 }

Answer 1

尝试通过带有@JoinColumn批注的referencedColumnName传递名称。它对我有用。

@ManyToOne(optional = false)
@JoinColumn(name = "userTypeId", referencedColumnName = "id",nullable = false)
private UserType userType;

我的实体是User和UserType，其中User具有属性“ userTypeId”作为外键。