用属性休眠多对多答案

【问题标题】：Nhibernate many to many with property用属性休眠多对多
【发布时间】：2021-09-03 14:56:30
【问题描述】：

嘿，我需要 NHibernate 中的多对多关系方面的帮助，我收到此错误：

NHibernate.MappingException: Unable to build the insert statement for class SelfHost.Core.Repository.implementation.HibernateProduktHaendler: a failure occured when adding the Id of the class ---> System.ArgumentException: The column 'Produkt_P_ID' has already been added in this SQL builder (Parameter 'columnName')

我有 3 个表 produkt、Haendler 和 ProduktHaendler，ProduktHaendler 同时将 Haendler_H_ID 作为主键和外键，同时将 Produkt_P_ID 作为主键和外键（我认为这是问题所在）

这是我的类 Prdoukthaendler 和映射

 using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;


namespace SelfHost.Core.Repository.implementation
{
  public  class HibernateProduktHaendler
    {
        public virtual HibernateProdukt Produkt_P_ID { set;get; }

        public virtual string ProduktURL { set; get; }
        public virtual HibernateHaendler Haendler_H_ID { set; get; }


       

        public override bool Equals(object obj)
        {
            if (obj == null)
                return false;
            HibernateProduktHaendler id;
            id = (HibernateProduktHaendler)obj;
            if (id == null)
                return false;
            if (Produkt_P_ID == id.Produkt_P_ID && Haendler_H_ID == id.Haendler_H_ID)
                return true;
            return false;
        }


        public override int GetHashCode()
        {
            return (Produkt_P_ID + "|" +Haendler_H_ID).GetHashCode();
        }

    }
}

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

    <class name="HibernateProduktHaendler" table="ProduktHaendler">
        

        <id  class="HibernateProduktHaendler">
            <key-property name="Produkt_P_ID"   type="int"></key-property>
            <key-property name="Haendler_H_ID"  type="int"></key-property>
        
    
    
        </id>

        <property name="ProduktURL" />

        <many-to-one  name="Produkt_P_ID"  ></many-to-one>

        <many-to-one  name="Haendler_H_ID" ></many-to-one>
            
        

    </class>

</hibernate-mapping>

【问题讨论】：

标签： c# sql hibernate nhibernate many-to-many

【解决方案1】：

我相信您正在寻找的是composite-id 映射。您不需要其他多对一映射。

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

<class name="HibernateProduktHaendler" table="ProduktHaendler">
    
    <composite-id>
        <key-many-to-one name="Produkt_P_ID" />
        <key-many-to-one name="Haendler_H_ID" />       
    </composite-id>

    <property name="ProduktURL" />

</class>
</hibernate-mapping>

【讨论】：