NHibernate多对多-如何从连接表中检索属性并将其与子级关联? [英] NHibernate many-to-many - how to retrieve property from join table and associate it with a child?

问题描述

我在SQL中已有一个多对多关系，该关系已通过NHibernate映射到我的业务实体.

I have an existing many-to-many relationship in SQL that is being mapped to my business entities via NHibernate.

我想为子级添加一个属性(以下类别)，该属性仅适用于父级和子级之间的关系.在SQL中，我会将一个字段添加到联接表中.

I want to add a property to the child (Category below) that is only applicable to the relationship between the parent and the child. In SQL, I would add a field to the join table.

如何使用NHibernate从联接表中提取该值并将其与孩子的财产相关联?

How do I use NHibernate to pull that value from the join table and associate it with a child's property?

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
  namespace="MyProject.Core.Entities"
  assembly="MyProject.Core">

  <class name="Product" table="Products" lazy="false">

    <id name="ProductId" access="field">
      <generator class="native" />
    </id>

    <property name="ProductName" access="field" />

    <idbag name="Categories" table="ProductCategory">
      <collection-id column="ProductCategoryId" type="int">
        <generator class="native" />                
      </collection-id>
      <key column="ProductId" />
      <many-to-many column="CategoryId" class="Category" />
    </idbag>

  </class>
</hibernate-mapping>

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
  namespace="MyProject.Core.Entities"
  assembly="MyProject.Core">

  <class name="Category" table="Categories" lazy="false">

    <id name="CategoryId" access="field">
      <generator class="native" />
    </id>

    <property name="CategoryName" access="field" />

  </class>
</hibernate-mapping>

推荐答案

基本答案是必须声明联接表并为其创建一个类.在这里可以找到类似的问题:

The basic answer is that you have to declare your joining table and create a class for it. A similar question can be found here:

如何在连接表(Fluent NHibernate)上使用具有属性(列)的NHibernate ManyToMany

基于评论的说明:

Product one-to-many ProductCategory
Category one-to-many ProductCategory
ProductCategory many-to-one Product
ProductCategory many-to-one Category

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