我尝试使用 hibernate 5.2 实现单表继承。 基类
@Entity
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="type", discriminatorType= DiscriminatorType.STRING)
@DiscriminatorValue("HAKSAHIBI")
@DiscriminatorOptions(force=true)
public class PropertyOwner implements implements Serializable{
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
long id;
@ManyToOne
Property property;
@ManyToOne
Person person;
}
作者类扩展了 PropertyOwner :
@Entity
@DiscriminatorValue("AUTHOR")
class Author extends PropertyOwner {
}
Composer 类扩展了 PropertyOwner :
@Entity
@DiscriminatorValue("COMPOSER")
class Composer extends PropertyOwner {
}
人员类别:
public class Person {
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
long id;
String title;
}
属性类别
public class Property{
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
long id;
String title;
@OneToMany
Set<Composer> composers = new HashSet<Composer>();
@OneToMany
Set<Author> authors = new HashSet<Author>();
}
我期望表结构如下:
CREATE TABLE `Property` (
`id` bigint(20) NOT NULL,
`title` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE `Person` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`title` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE `PropertyOwner` (
`type` varchar(31) NOT NULL,
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`property_id` bigint(20) DEFAULT NULL,
`person_id` bigint(20) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `FK77apjkkl14xwe45rs1ocgtt4u` (`property_id`),
KEY `FKqagfofgupovfly26enivfhm3j` (`person_id`),
CONSTRAINT `FK77apjkkl14xwe45rs1ocgtt4u` FOREIGN KEY (`property_id`) REFERENCES `property` (`id`),
CONSTRAINT `FKqagfofgupovfly26enivfhm3j` FOREIGN KEY (`person_id`) REFERENCES `person` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
但不幸的是,它使用以下语句为 Author 和 Composer 类创建了另一个表
CREATE TABLE `property_propertyOwner` (
`Property_id` bigint(20) NOT NULL,
`author_id` bigint(20) NOT NULL,
`composer_id` bigint(20) NOT NULL,
UNIQUE KEY `UK_rv9fxc06rcydqp6dqpqbmrkie` (`author_id`),
UNIQUE KEY `UK_fm4v55i021l5smuees0vs3qmy` (`composer_id`),
KEY `FKt3yqcltkd0et8bj08ge0sgrqb` (`Property_id`),
CONSTRAINT `FK1pj2606cjxrb70ps89v7609hg` FOREIGN KEY (`author_id`) REFERENCES `PropertyOwner` (`id`),
CONSTRAINT `FKfdh3r95jffvd07u3xn21824r7` FOREIGN KEY (`composer_id`) REFERENCES `PropertyOwner` (`id`),
CONSTRAINT `FKt3yqcltkd0et8bj08ge0sgrqb` FOREIGN KEY (`Property_id`) REFERENCES `Property` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
我做错了什么?我期望不应创建 property_PropertyOwner 表,并且 Author 、 Composer 类信息应保存在 propertyOwner 表中。
注意:我尝试了枚举注释,但这次在 Property 类中我无法定义 Setauthor 字段,我必须定义 Set 并向该对象添加枚举信息。 提前致谢 。
最佳答案
在您的属性(property)实体中拥有子类( Composer 和作者)的多个关联是没有意义的。因为您具有单表继承,即您的属性(property)所有者表将具有 property_id 的外键。 因此,您可以拥有单一关联。
@OneToMany
Set<PropertyOwner> composers = new HashSet<PropertyOwner>();
您可以使用 DiscriminatorColumn 类型在内存中将此集合拆分为作者和 Composer 。
关于java - Hibernate 继承 SingleTable,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/42746192/