一对多在NHibernate的映射问题

Question

我有这样的：

namespace Demo.Framework.Domain 
{ 
    public class UserEntity 
    { 
     public virtual Guid UserId { get; protected set; } 
    } 
} 

namespace TDemo.Framework.Domain 
{ 
    public class Users : UserEntity 
    { 
     public virtual string OpenIdIdentifier { get; set; } 
     public virtual string Email { get; set; } 
     public virtual IList<Movie> Movies { get; set; } 
    } 
} 

namespace Demo.Framework.Domain 
{ 
    public class Movie 
    { 
     public virtual int MovieId { get; set; } 
     public virtual Guid UserId { get; set; } // not sure if I should inherit UserEntity 
     public virtual string Title { get; set; } 
     public virtual DateTime ReleaseDate { get; set; } // in my ms sql 2008 database I want this to be just a Date type. Not sure how to do that. 
     public virtual int Upc { get; set; } 

    } 
} 

<?xml version="1.0" encoding="utf-8" ?> 
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" 
    assembly="Demo.Framework" 
    namespace="Demo.Framework.Domain"> 
    <class name="Users"> 
     <id name="UserId"> 
      <generator class="guid.comb" /> 
     </id> 
     <property name="OpenIdIdentifier" not-null="true" /> 
     <property name="Email" not-null="true" />  
    </class> 
    <subclass name="Movie"> 
     <list name="Movies" cascade="all-delete-orphan"> 
      <key column="MovieId" /> 
      <index column="MovieIndex" /> // not sure what index column is really. 
      <one-to-many class="Movie"/> 
     </list> 
    </subclass>  
</hibernate-mapping> 

<?xml version="1.0" encoding="utf-8" ?> 
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" 
    assembly="Demo.Framework" 
    namespace="Demo.Framework.Domain"> 
    <class name="Movie">  
     <id name="MovieId"> 
      <generator class="native" /> 
     </id> 
     <property name="Title" not-null="true" /> 
     <property name="ReleaseDate" not-null="true" type="Date" /> 
     <property name="Upc" not-null="true" /> 
     <property name="UserId" not-null="true" type="Guid"/> 
    </class> 
</hibernate-mapping> 

我得到这个错误：

'extends' attribute is not found or is empty. 

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: NHibernate.MappingException: 'extends' attribute is not found or is empty. 

Source Error: 

Line 19:    var nhConfig = new Configuration().Configure(); 
Line 20:    var sessionFactory = nhConfig.BuildSessionFactory(); 

Answer 1

NHibernate的有它在Java中，其中一个子类“扩展”一个基类的根，当定义不同hbm文件的hierach时，这有时是一个有用的映射元素。

您看到错误是您将用户电影映射为“子类”的方式的原因。这是令人困惑的NHib，因为你没有扩展任何东西。删除列表中的“子类”节点，该错误将消失。

顺便说一句，杰米是正确的，为什么列表索引是必需的。列表映射很好，但除非有一个令人信服的理由不这样做，否则我通常需要为我的一对多关系设置语义，如下面的示例中的hbm。

HTH，
Berryl

<set access="field.camelcase-underscore" cascade="none" inverse="true" name="Employees"> 
    <key foreign-key="Employee_Department_FK"> 
    <column name="DepartmentId" /> 
    </key> 
    <one-to-many class="Employee" /> 
</set>