nHibernate 2.0-映射复合ID *和*多对一关系会导致“无效索引".错误 [英] nHibernate 2.0 - mapping a composite-id *and* many-to-one relationship causes "invalid index" error

问题描述

我有问题.想象一下这个数据模型:

I have a problem. Imagine this data model:

[Person] table has: PersonId, Name1  
[Tag] table has:  TagId, TagDescription  
[PersonTag] has: PersonId, TagId, IsActive

由于[PersonTag]不仅仅是一个简单的多对多联接表，所以我在nHibernate中创建了所有三个实体(就像它们在数据模型中一样).因此，PersonTag需要一个复合ID，我已将其映射到这样的类:

Since [PersonTag] isn't just a simple many-to-many join table, I have all three entities created in nHibernate (exactly like they are in the data model). PersonTag, therefore, needs a composite-id, which I have mapped to a class like this:

<composite-id name="PersonTagKey" class="PersonTagKey">
  <key-property name="PersonId"></key-property>
  <key-property name="TagId"></key-property>
</composite-id> 

我想遍历对象图，并能够从检索到的PersonTag对象中同时查看Person和Tag对象.因此，我在PersonTag对象上具有执行此操作的属性，如下所示:

I want to traverse the object graph and be able to look at both the Person and Tag objects from a retrieved PersonTag object. So, I have properties on the PersonTag object to do that, mapped like this:

<many-to-one name="Person" column="PersonId" lazy="proxy" cascade="none" class="Person"/>
<many-to-one name="Tag" column="TagId" lazy="proxy" cascade="none" class="Tag"/>

当我尝试创建一个PersonTag对象并保存它时，我得到一个此SqlParameterCollection的无效索引n，计数为n""错误.我知道这是因为我已经将PersonId和TagId属性映射了两次，一次是针对复合ID，一次是针对多对一关系.如果我不映射多对一对象，则一切正常.

When I try to create a PersonTag object and save it, I get an "Invalid index n for this SqlParameterCollection with Count=n" error. I know this is because I've mapped the PersonId and TagId properties twice, once for the composite-id, and once for the many-to-one relationship. If I don't map the many-to-one objects, then everything works fine.

我是否有某种方法可以基于在同一nHibernate实体中建模的同一列建立复合ID和多对一关系?

推荐答案

好，这就是答案.几乎没有相关文档:

Kay, here's the answer. Little-to-no documentation on this:

<composite-id name="PersonTagKey" class="PersonTagKey"> 
  <key-many-to-one name="Person" column="PersonId" lazy="proxy" class="Person">
  <key-many-to-one name="Tag" column="TagId" lazy="proxy" class="Tag"/>
</composite-id>

这将允许您创建由多对一关系的逆构成的复合ID.

This will allow you to create a composite-id made up of the inverse of a many-to-one relationship.

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