如何克隆JPA实体 [英] How to clone a JPA entity

问题描述

我已经在数据库中保留了一个JPA实体.
我想拥有一个副本(具有不同的ID)，并修改了某些字段.

I have a JPA entity already persisted in the database.
I would like to have a copy of it (with a different id), with some fields modified.

最简单的方法是什么?喜欢:

What is the easiest way to do this? Like:

• 将它的@Id字段设置为null并保留它会起作用吗?
• 我是否需要为实体创建一个克隆方法(复制除@Id以外的所有字段)?
• 还有其他方法(例如使用克隆框架)吗?

• setting it's @Id field to null and persisting it will work?
• will I have to create a clone method for the entity (copying all fields except the @Id)?
• is there any other approach (like using a cloning framework)?

推荐答案

使用EntityManager.detach.它使bean不再链接到EntityManager.然后将ID设置为新ID(如果为自动，则为null)，更改所需字段并保留.

Use EntityManager.detach. It makes the bean no longer linked to the EntityManager. Then set the Id to the new Id (or null if automatic), change the fields that you need and persist.

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