NHibernate：删除的对象将被级联重新保存。替换对象并删除旧的 [英] NHibernate: deleted object would be re-saved by cascade. Replace object and remove old one

问题描述

我试图在ProgramItem的TimeBlock对象上进行替换，然后删除旧的TimeBlock对象。这是删除部分，给我的问题。
我有一些'相对的'简单nHibernate probelms删除旧的TimeBlock对象。

例外：

删除的对象将被级联重新保存（从关联中删除删除的对象）[* .ModelTimeBlock＃15]

15是oldTimeBlock的Id p>

我一般都没有任何问题来解决这种问题，我只是尝试了任何用法：

  oldTimeBlock.ProgramItems = new List< ProgramItem>（）; 
 programItem.TimeBlock = null; 
  

以及任何顺序的保存和删除块，并用Inverse（） >
我需要一些新鲜的眼睛 - 我怎么能做到这一点？
$ b 代码：

  public class TimeBlock 
 {
 public virtual int Id {get;组; } 
公共虚拟IList< ProgramItem> ProgramItems {get;组; } 
 ... 
} 
 
 public class TimeBlockMap：ClassMap< TimeBlock> 
 {
 public TimeBlockMap（）
 {
 Id（x => x.Id）; 
 HasMany（x => x.ProgramItems）.Cascade.SaveUpdate（）; //已经使用Inverse（）进行了测试，但似乎没有任何区别
} 
} 
 
 
 public class ProgramItem：ImageModel，IIdentifiable 
 {
 public virtual int Id {get;组; } 
 public virtual TimeBlock TimeBlock {get;组; } 
 ... 
} 
 
 public class ProgramItemMap：ClassMap< ProgramItem> 
 {
 public ProgramItemMap（）
 {
 Id（x => x.Id）; 
参考文献（x => x.TimeBlock）; 
} 
} 
 
 
 //删除旧的TimeBlock并将新的TimeBlock设置为ProgramItem 
 
 var oldTimeBlock = programItem.TimeBlock; 
 
 using（var tx = session.BeginTransaction（））
 {
 oldTimeBlock.ProgramItems = new List< ProgramItem>（）; 
 programItem.TimeBlock = null; 
 //session.Save(programItem）; 
 //session.Save (oldTimeBlock）; 
 session.Delete（oldTimeBlock）; 
 tx.Commit（）; //异常的位置如果我移动save programItem部分下面的删除oldTimeBlock部分，它仍然会在删除oldTimeBlock部分失败。 
 
 
 using（var tx = session.BeginTransaction（））
 {
 programItem.TimeBlock = timeBlock; 
 session.Save（programItem）; 
 tx.Commit（）; 
 
  

解决方案

在这里详细

• NHibernate删除对象将是通过级联重新保存


• 从多对多关系中删除项目

我会说，重点在这里： ProgramItem 被其他一些集合引用。那个集合也加载到会话中。

开始的最佳位置是 - 无论使用哪个ProgramItem（集合项目，引用），都将映射更改为 Cascade.None（） code>。然后尝试执行您的删除代码。这将工作...当然，因为现在级联...没有办法如何触发这种异常。

下一步 - 开始级联。确保你知道什么是允许的，然后你将知道哪些引用，集合重新保存你的对象。

我自己的经验/方法是 - 如果你删除项目从一个地方，明确地从其他人删除，如果有级联。这可能是具有挑战性的，但... ...

I am trying to replace at TimeBlock object on a ProgramItem and then delete the old TimeBlock object. It is the delete part that gives me problems. I have some 'relative' simple nHibernate probelms deleting the old TimeBlock object.

Exception:
deleted object would be re-saved by cascade (remove deleted object from associations)[*.Model.TimeBlock#15]
15 is the Id of the oldTimeBlock

I usaully doesn't have any problems solving this kind of issue by I just tried amost any usages of:

oldTimeBlock.ProgramItems = new List<ProgramItem>();
programItem.TimeBlock = null;

and the save and delete blocks in any order and changing the mapping with Inverse().
I need some fresh eyes - how could I make this work?

Code:

public class TimeBlock
{
    public virtual int Id { get; set; }
    public virtual IList<ProgramItem> ProgramItems { get; set; }
    ...
}

public class TimeBlockMap : ClassMap<TimeBlock>
{
    public TimeBlockMap()
    {
        Id(x => x.Id);
        HasMany(x => x.ProgramItems).Cascade.SaveUpdate(); // Have tested with Inverse() but seemed to make no difference
    }
}


public class ProgramItem : ImageModel, IIdentifiable
{
    public virtual int Id { get; set; }
    public virtual TimeBlock TimeBlock { get; set; }
    ...
}

public class ProgramItemMap : ClassMap<ProgramItem>
{
    public ProgramItemMap()
    {
        Id(x => x.Id);
        References(x => x.TimeBlock);
    }
}


//Delete old TimeBlock and set new TimeBlock to ProgramItem

var oldTimeBlock = programItem.TimeBlock;

using (var tx = session.BeginTransaction())
{
    oldTimeBlock.ProgramItems = new List<ProgramItem>();
    programItem.TimeBlock = null;
    //session.Save(programItem);
    //session.Save(oldTimeBlock);
    session.Delete(oldTimeBlock);
    tx.Commit(); // location of the exception. If i move the delete oldTimeBlock part below the save programItem part it will still fail in the delete oldTimeBlock part.
}

using (var tx = session.BeginTransaction())
{
    programItem.TimeBlock = timeBlock;
    session.Save(programItem);
    tx.Commit();
}

解决方案

I tried explain what is happening in detail here

• NHibernate Deleted object would be re-saved by cascade
• Delete an item from many-to-many relationship

I would say, that the point is here: the ProgramItem is referenced by some other collection. And that collection was also loaded into the session.

The best place where to start is - wherever is ProgramItem used (collection item, reference) change the mapping to Cascade.None(). Then try to execute your deletion code. That will work... surely, becuase now cascading in place... no way how to trigger that exception.

Next - start cascading by pieces. Be sure you know what is allowed, and then you will know which reference, collection is re-saving your object.

My own experience/approach is - if you delete the item from one place, explicitly delete it from others as well, if there is cascade. It could be challenging, but...

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