外键休眠注释

Question

我无法设法使这个简单的外键约束工作。

@Entity 
@Table(name = "wheel") 
@Data 
public class WheelEntity { 
    @Id 
    @Column(name = "id") 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private Integer id; 
    ... 

@Entity 
@Table(name = "bike") 
@Data 
public class BikeEntity { 
    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private Integer id; 

    @ManyToOne(targetEntity = WheelEntity.class, fetch=FetchType.EAGER, cascade={CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE}) 
    @JoinColumn(name = "wheel_1_id", referencedColumnName = "id") 
    @NotNull 
    private Integer wheel_1_id; 

    @ManyToOne(targetEntity = WheelEntity.class, fetch=FetchType.EAGER, cascade={CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE}) 
    @JoinColumn(name = "wheel_2_id", referencedColumnName = "id") 
    @NotNull 
    private Integer wheel_2_id; 
    ... 

当我要插入一个新的自行车，这里是持续的BikeEntity时，我得到的错误：

Caused by: java.lang.IllegalArgumentException: Can not set java.lang.Integer field com.xxx.xxx.xxx.storage.WheelEntity.id to java.lang.Integer 
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167) 
    at sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171) 
    at sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58) 
    at sun.reflect.UnsafeObjectFieldAccessorImpl.get(UnsafeObjectFieldAccessorImpl.java:36) 
    at java.lang.reflect.Field.get(Field.java:393) 
    at org.hibernate.property.access.spi.GetterFieldImpl.get(GetterFieldImpl.java:39) 

无法设置为java.lang.Integer到java.lang.Integer中。 MMMMMM？奇怪！

的帮助

Answer 1

非常感谢在休眠您具有内部ENTITY2 ENTITY1参考创建关系。正确的方法是：

@Entity 
@Table(name = "wheel") 
@Data 
public class WheelEntity { 
    @Id 
    @Column(name = "id") 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private Integer id; 
    ... 

@Entity 
@Table(name = "bike") 
@Data 
public class BikeEntity { 
    @Id 
    @GeneratedValue(strategy = GenerationType.IDENTITY) 
    private Integer id; 

    @ManyToOne(targetEntity = WheelEntity.class, fetch=FetchType.EAGER, cascade={CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE}) 
    @JoinColumn(name = "wheel_1_id", referencedColumnName = "id") 
    @NotNull 
    private WheelEntity wheelEntity;