使用Hibernate将可变转换为不可变 [英] Converting Mutable to Immutable with Hibernate

问题描述

 类包{
字符串代码
 
发布日期日期
 //其他几个属性（包括集合hasMany）.... 
 
 def isPublished（）{
 return publishedDate！= null $ 
 
 $ b def publish（）{
 publishedDate = new Date（）
} 
 
 def canEdit（）{
 return ！isPublished（）
} 
} 
  

发布它并且我使用发布方法来发布一个包。

发布后，一个包不能改变（即发布后，一个包需要是一个不可变的实例） 。

我的问题是：

• 如何在不可变使用中转换Mutable对象Groovy的？

或

• 有没有办法从Hibernate中检索一个不可变的实例？另一个选择是使用canEdit（）方法结合Hibernate事件（beforeUpdate和beforeDelete ）。如果canEdit（）== false，那么我可以在beforeDelete或beforeUpdate中引发RuntimeException。是一个很好的解决方案吗？
  
  
  

  Obs .:我认为Ruby中的冻结方法正是我所需要的。 （ http://rubylearning.com/satishtalim/mutable_and_immutable_objects.html ）

  解决方案

  您可以使用 Pack.read（id）来获得
  
  

  
  

  处于只读状态的指定标识的域类实例。如果具有指定id的行不存在，则返回null。
  

  请参阅 http://grails.org/doc/latest/ref/Domain%20Classes/read.html

  
  

  I'm using Grails and I have the following domain class:

  class Pack {
    String code
  
    Date publishedDate
    //several other properties (including collections hasMany)....
  
    def isPublished() {
      return publishedDate != null
    }
  
    def publish() {
      publishedDate = new Date()    
    }
  
    def canEdit() {
      return !isPublished()
    }
  }
  

  To sell a Pack I first need publish it and I use the publish method to publicate a Pack.

  After published, a Pack cannot be changed (i.e. after published, a Pack need to be a immutable instance).

  My question is:

  • How to transform a Mutable object in Immutable using Groovy?

  or

  • Is there a way to retrieve a Immutable instance from Hibernate?

  Another option is to use the canEdit() method combined with the Hibernate events (beforeUpdate and beforeDelete). If canEdit() == false then I can throw a RuntimeException inside the beforeDelete or beforeUpdate. Is a good solution?

  Obs.: I think that the freeze method in Ruby does exactly what I need. (http://rubylearning.com/satishtalim/mutable_and_immutable_objects.html)

  解决方案

  you can use Pack.read( id ) to get

  an instance of the domain class for the specified id in a read-only state. null is returned if the row with the specified id doesn't exist.

  see http://grails.org/doc/latest/ref/Domain%20Classes/read.html

  这篇关于使用Hibernate将可变转换为不可变的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！