解决org.hibernate.ObjectDeletedException: deleted object would be re-saved by cascade (remove deleted object from associations)

相关代码：
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public class VoteQuestion {
    private Set options = new HashSet();
    。。。

 /**
  * @hibernate.set cascade = "all" table = "VOTE_OPTION" inverse =
  *                "true" lazy = "true" order-by = "id"
  *
  * @hibernate.collection-one-to-many class =
  *                                   "eorg.etoken.pojo.VoteOption"
  *
  * @hibernate.collection-key column = "QUESTION_ID"
  */
 public Set getOptions() {
        return options;
 }

}

public class VoteOption {
    private VoteQuestion question;
    。。。。

 /**
  * @hibernate.many-to-one class = "eorg.etoken.pojo.VoteQuestion" cascade =
  *                        "none" not-null = "true" column = "QUESTION_ID"
  *                        update = "false"
  */
 public VoteQuestion getQuestion() {
       return question;
 }

}

public class VoteServiceImpl{
 。。。
 public void deleteVoteOption(int optionId) {
      Transaction tx = session.beginTransaction();
      VoteOption option = (VoteOption) session.load(VoteOption.class, new Long(optionId));
      session.delete(option);
      tx.commit();
 }
}

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当调用VoteServiceImpl的deleteVoteOption方法时，就会抛出下列Exception:
org.hibernate.ObjectDeletedException: deleted object would be re-saved by cascade (remove deleted object from associations)

原因是votequestion与voteoption有连带关系，不能直接删除voteoption，而应该从votequestion里remove voteoption！

因此上面的deleteVoteOption方法只需要修改一行即可，见下面代码

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 public void deleteVoteOption(int optionId) {
      Transaction tx = session.beginTransaction();
      VoteOption option = (VoteOption) session.load(VoteOption.class, new Long(optionId));
      option.getQuestion().getOptions().remove(option);
      tx.commit();
 }
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