Nhibernate 3.2代码映射.当我们创建一个袋子关系时，什么是rm.一对多

我通过代码使用nhibernate 3.2映射，我有一个奇怪的行为。

如果我简化我的项目，我有两个表：

[Serializable]
public class Intervention
{
    public Intervention()
    {
        ReponsePointVerification = new List<ReponsePointVerification>();
    }
    #region Public Properties
    public virtual int Id
    {
        get;
        set;
    }
    public virtual IList<ReponsePointVerification> ReponsePointVerification
    {
        get;
        set;
    }
}
public class InterventionMap : ClassMapping<Intervention>
{
    public InterventionMap()
    {
        Id<int>(x => x.Id, map =>
        {
            map.Generator(NHibernate.Mapping.ByCode.Generators.Identity);
        });
        Bag(x => x.ReponsePointVerification, map =>
        {
            map.Key( k => k.Column( "IdIntervention" ) );
        }); 
    }
}

和

[Serializable]
public class ReponsePointVerification
{
    #region Public Properties
    public virtual int Id
    {
        get;
        set;
    }
    public virtual Intervention Intervention
    {
        get;
        set;
    }
}
public class ReponsePointVerificationMap : ClassMapping<ReponsePointVerification>
{
    public ReponsePointVerificationMap()
    {
        Id<int>(x => x.Id, map =>
        {
            map.Generator(NHibernate.Mapping.ByCode.Generators.Identity);
        });
        ManyToOne<Intervention>(x => x.Intervention, map => map.Column("IdIntervention"));
    }
}

其表示两个表Intervention和ReponsePointVerification，其具有链接到Intervention的外键（IdIntervention）。

当我打电话时：

        return (from interv in Session.Query<Intervention>()
                .Fetch(rep => rep.ReponsePointVerification)
                select interv).ToList();

甚至当我没有获取信息时。我有这个错误：

Could not cast the value in field id0_ of type Int32 to the Type SerializableType.  Please check to make sure that the mapping is correct and that your DataProvider supports this Data Type.

sql查询看起来不错。

我找到了那个帖子http://groups.google.com/group/nhusers/browse_thread/thread/ef137c3e5b66acdc

我根据帖子修改了InterventionMap类，它将起作用：

public class InterventionMap : ClassMapping<Intervention>
{
    public InterventionMap()
    {
        Id<int>(x => x.Id, map =>
        {
            map.Generator(NHibernate.Mapping.ByCode.Generators.Identity);
        });
        Bag(x => x.ReponsePointVerification, map =>
        {
            map.Key( k => k.Column( "IdIntervention" ) );
        }, rm => rm.OneToMany()); 
    }
}

唯一的区别是添加了"，rm=>rm.OneToMany（）"

相信我，我很高兴它成功了，但我真的不明白这句话，有人能解释我的意思吗？

问候

编辑

我做了一个WriteAllXmlMapping，这两个代码是：

不带rm=>rm的版本。OneToMany（）（无效）

<bag name="ReponsePointVerification">
  <key column="IdIntervention" />
  <element type="Hyma.BusinessObjets.ReponsePointVerification" />
</bag>

带有rm=>rm的版本。OneToMany（）（有效）

<bag name="ReponsePointVerification">
  <key column="IdIntervention" />
  <one-to-many class="ReponsePointVerification" />
</bag>

class Parent
{
    public ICollection<Child> Childs { get; set; }  <- one-to-many collection
    public ICollection<string> Names { get; set; }  <- element collection
}
class Child
{
    public int Id { get; set; }
    public string Name { get; set; }
}

ParentTable
id
ChildTable
id | parent_id | name
NamesTable
parent_id | name