英文:
Is there a way to use share embeddable object in Hibernate?
问题
我遇到了可重复使用的类字段的情况，我想将它们标记为@embeddable，然而问题是 - JPA是否允许在其他不同的类中多次重复使用一个类作为embeddable呢？
例如，我的可嵌入类如下所示：
@Embeddable
@Data
public class Audit{
private String name;
private Audit auditor;
private LocalDateTime creationDate;
}
是否可以像以下示例一样将Audit嵌入多个不同的类中：
@Entity
@Table(name = "BANK")
public class Bank{
@Id
private Long id;
@Column(name = "BANK_NAME")
private String bankName;
@Embedded
private Audit audit;
}
以及
@Entity
@Table(name = "CORPORATION")
public class Corporation{
@Id
private Long id;
@Column(name = "CORPORATION_NAME")
private String corporationName;
@Embedded
private Audit audit;
}
英文:
I have a situation with repeatable class fields which I want to mark as @embeddable, however the question is - does JPA allow re-utilizing a class multiple times as embeddable in other different classes?
E.g. my embeddable class looks as follows:
@Embeddable
@Data
public class Audit{
private String name;
private Audit auditor;
private LocalDateTime creationDate;
}
Is it possible to embed the Audit into multiple different classes as for ex.:
@Entity
@Table(name = "BANK")
public class Bank{
@Id
private Long id;
@Column(name = "BANK_NAME")
private String bankName;
@Embedded
private Audit audit;
}
AND
@Entity
@Table(name = "CORPORATION")
public class Corporation{
@Id
private Long id;
@Column(name = "CORPORATION_NAME")
private String corporationName;
@Embedded
private Audit audit;
}
答案1
得分: 0
历史上，Hibernate 称这些组件为 "components"。而 JPA 则称其为 [embeddables](https://docs.jboss.org/hibernate/orm/5.4/userguide/html_single/Hibernate_User_Guide.html#embeddables)。不管怎样，概念是相同的：一种值的组合。
通常，可嵌入类型被用于**将多个基本类型映射**分组，并在多个实体之间**重用**。
Java 代码示例：
```java
@Data
@Entity(name = "Book")
public class Book {
@Id
@GeneratedValue
private Long id;
private String title;
private String author;
private Publisher publisher;
}
@Data
@Embeddable
public static class Publisher {
@Column(name = "publisher_name")
private String name;
@Column(name = "publisher_country")
private String country;
}
以下是 SQL，展示了你的表应该是什么样子的：
create table Book (
id bigint not null,
author varchar(255),
publisher_country varchar(255),
publisher_name varchar(255),
title varchar(255),
primary key (id)
)
更多细节可以在文档中找到 🙂
<details>
<summary>英文:</summary>
Historically Hibernate called these components. JPA calls them [embeddables](https://docs.jboss.org/hibernate/orm/5.4/userguide/html_single/Hibernate_User_Guide.html#embeddables). Either way, the concept is the same: a composition of values.
Most often, embeddable types are used **to group** multiple basic type mappings **and reuse them** across several entities.
Java Code Example:
@Data
@Entity(name = "Book")
public class Book {
@Id
@GeneratedValue
private Long id;
private String title;
private String author;
private Publisher publisher;
}
@Data
@Embeddable
public static class Publisher {
@Column(name = "publisher_name")
private String name;
@Column(name = "publisher_country")
private String country;
}
And this is SQL to show how your table should look like:
create table Book (
id bigint not null,
author varchar(255),
publisher_country varchar(255),
publisher_name varchar(255),
title varchar(255),
primary key (id)
)
More details can be found in the [documentation](https://docs.jboss.org/hibernate/orm/5.4/userguide/html_single/Hibernate_User_Guide.html#embeddables) :)
</details>
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