我可以仅使用ID设置实体关系吗？ [英] Can I set an entity relation with just the ID?

问题描述

我有一个JPA（Hibernate）实体：

  @Entity类Transaction {
 
 @ ManyToOne 
私人房间; 
 
 
  

当我创建一个新的 Transaction ，我知道它应该引用的 Room 的I​​D（但没有 Room object）。我能以某种方式创建并保存 Transaction 这个信息，或者我确实需要：

 房间= em.find（roomId，Room.class）; 
 em.persist（new Transaction（room，...））; 
  

解决方案

我遇到了类似的问题，但可能并非最佳做法。

现在由于映射取决于 roomId 创建构造函数房间（类型roomId ）并在保存事务bean 之前设置该bean。所以需要从数据库中获取数据。 hibernate关心Id，它需要映射这些bean。

我已经使用这种方法来获取数据，我希望你不要当您更新交易时，会被更新。因此，将 insert，update映射的属性设置为false。

I have a JPA (Hibernate) entity:

@Entity class Transaction {

  @ManyToOne
  private Room room;

}

When I create a new Transaction, I know the ID of the Room that it should refer to (but don't have a Room object). Can I somehow create and persist a Transaction with just this info, or do I really need to:

Room room = em.find(roomId, Room.class);
em.persist(new Transaction(room, ...));

解决方案

I had a similar problem where I found an alternate solution but may be its not a best practice.

Now since the mapping is depending on the roomId create a constructor Room(Type roomId) and set that bean before you save Transaction bean. So need to get the data from the DB. What hibernate cares about the Id that it needs to map the beans.

I have used this approach to get the data and I hope you don't want the Room to get updated when you update Transaction. So set the insert,update properties of the mappings to false.

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