java 使用 @OneToMany 或 @ManyToMany 在休眠中针对未映射的类异常
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Use of @OneToMany or @ManyToMany targeting an unmapped class Exception in hibernate
提问by Yo Yo Money Singh
Forgive me since I am rookie to hibernate and other answers on similar questions didn't quite fix this issue(I am sure my issue is quite basic). I am trying to have a OneToMany and ManyToOne mapping in my persistence classes. I have following tables:
原谅我，因为我是休眠的新手，类似问题的其他答案并没有完全解决这个问题（我确信我的问题很基本）。我试图在我的持久性类中有一个 OneToMany 和 ManyToOne 映射。我有以下表格：
city (
id INT AUTO_INCREMENT,
name VARCHAR(255),
)
pincode (
id INT AUTO_INCREMENT,
pincode VARCHAR(6),
city_id INT FOREIGN KEY fk_city_id ON city(id)
)
area (
id INT AUTO_INCREMENT,
name VARCHAR(255),
pincode_id INT FOREIGN KEY fk_pincode_id ON pincode(id)
)
The following persistence class I wrote: For City:
我写的以下持久性类：对于城市：
@Table(name="city")
@Entity
City {
@Id
private Integer id;
@Column(name="name")
private String name;
}
For PinCode:
对于密码：
@Table(name="pincode")
@Entity
PinCode {
@Id
private Integer id;
@Column(name = "pincode")
private String pinCode;
@ManyToOne
@JoinColumn(name = "city_id")
private City city; //Multiple pincodes may be mapped to one city
//One pincode may have multiple areas
@OneToMany(fetch = FetchType.EAGER, mappedBy = "pincode_mapping")
@Fetch(value = FetchMode.SELECT)
private List<Area> area;
}
For Area:
对于地区：
@Entity
Area {
@Id
private Integer id;
@Column(name = "name")
private String name;
@ManyToOne(fetch = FetchType.EAGER, targetEntity = PinCode.class)
@Column(name = "pincode_id")
private PinCode pinCode; //Multiple areas may be mapped to one pincode
}
Facing the following exception:
面临以下异常：
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with
name 'sessionFactory' defined in class path resource [applicationContext-resources.xml]: Invocation of init method failed;
nested exception is org.hibernate.AnnotationException: Use of @OneToMany or @ManyToMany targeting an unmapped class: com.mycompany.model.PinCode.area[com.mycompany.model.Area]
回答by Matteo Baldi
You have to define your join column in the many to one annotation in your Area entity:
您必须在 Area 实体的多对一注释中定义连接列：
@ManyToOne(fetch = FetchType.EAGER, targetEntity = PinCode.class)
@JoinColumn(name = "pincode_id", nullable = false)
plus, in your Pincode entity you should indicate the correct field in the mappedByproperty:
另外，在您的 Pincode 实体中，您应该在mappedBy属性中指明正确的字段：
@OneToMany(fetch = FetchType.EAGER, mappedBy = "pincode")
回答by GHajba
The problem is that you use mappedBywrong: you add there the column name in the database however it has to be the property name in the Areaentity by the PinCodeis mapped:
问题是你用mappedBy错了：你在数据库中添加了列名，但是它必须是Area实体中的属性名PinCode被映射：
@OneToMany(fetch = FetchType.EAGER, mappedBy = "pinCode")
@Fetch(value = FetchMode.SELECT)
private List<Area> area;
And the JavaDoc of mappedBytells you the same:
JavaDoc ofmappedBy告诉你同样的事情：
The fieldthat owns the relationship. Required unless the relationship is unidirectional.
拥有关系的字段。除非关系是单向的，否则是必需的。
回答by Sergii Bishyr
I suppose you have something like this in your hibernate configuration
我想你的休眠配置中有这样的东西
<mapping class="com.mycompany.model.PinCode" />
Or, if you are using java config
或者，如果您使用的是 java 配置
.addAnnotatedClass(PinCode.class);
Make sure taht all your @Entityclasses are declared as mapping classes, or configure it to auto-scan
确保所有@Entity类都声明为映射类，或将其配置为自动扫描
