NHibernate3剖析：Mapping篇之ConfORM实战(3):OneToOne语义

2010-09-10 08:45 李永京阅读(6156) 评论(11) 编辑收藏举报

本节内容

系列引入
ConfORM概述
One-to-One语义
结语
参考资料

系列引入

NHibernate3剖析系列分别从Configuration篇、Mapping篇、Session篇、Core篇、Tool篇、Practice篇、Extension篇等方面全面揭示NHibernate3版本内容、特性及其应用，完全基于NHibernte3版本。

NHibernate专题：http://kb.cnblogs.com/zt/nhibernate/
NHibernate官方站点：http://nhforge.org/
NHibernate参考文档：http://nhforge.org/doc/nh/en/
获取NHibernate地址：http://sourceforge.net/projects/nhibernate/files/

ConfORM概述

在ConfORM实战(1):概览中，描述了ConfORM简单使用。在ConfORM实战(2):原理中介绍了ConfORM的基本实现原理。如果你不熟悉ConfORM请查看前几篇文章，你也可以到http://code.google.com/p/codeconform/获取ConfORM。

在这之前，我们需要为HbmMapping写AsString()扩展方法：用于输出HbmMapping对象的Mapping，用于学习测试使用，具体代码参考这里。

在Domain设计中，关联关系有单向关联和双向关联两种，那么一对一我们可以分为单向一对一关联(Unidirectional one-to-one)、双向一对一主键关联(Bidirectional one-to-one (primary key association))、双向一对一外键关联(Bidirectional one-to-one (foreign key association))三种情况。这篇使用ConfORM“映射”这些Domain实例吧。

One-to-One语义

我们使用ObjectRelationalMapper类中的OneToOne方法定义两个对象一对一关系。

单向一对一关联(Unidirectional one-to-one)

1.Domain

设计单向一对一关联Domain实例，Person对象和Address对象，人有一个地址。

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Address Address { get; set; }
}

public class Address
{
    public int Id { get; set; }
    public string Street { get; set; }
    public int CivicNumber { get; set; }
}

2.ConfORM

使用ConfORM来配置Domain，使之编译生成我们需要的HbmMapping对象。(注意黑体)

[Test]
public void UnidirectionalOneToOneMappingDemo()
{
    //show how work with one-to-one and how ConfORM understands OOP
    var orm = new ObjectRelationalMapper();
    var mapper = new Mapper(orm);
    var entities = new[] { typeof(Person), typeof(Address) };
    //use the definition of table-to-class strategy class by class
    orm.TablePerClass(entities);
    // Defining relations
    orm.OneToOne<Person, Address>();
    // Show the mapping to the console
    var mapping = mapper.CompileMappingFor(entities);
    Console.Write(mapping.AsString());
}

3.Mapping

上面测试输出HbmMapping的映射字符串，如果你使用ReSharper或者TestDriven.Net工具测试，你可以看见下面输出：

4.原理

对于单向一对一关联，实际就是设置IManyToOneMapper，ConfORM会在IPatternsAppliersHolder的ManyToOne和ManyToOnePath集合中匹配对应模式适配器，即匹配UnidirectionalOneToOneUniqueCascadeApplier模式适配器，进行相应操作。

UnidirectionalOneToOneUniqueCascadeApplier：应用IManyToOneMapper.Unique(true)和ManyToOneMapper.Cascade(applyCascade.HasValue?applyCascade.Value : Cascade.All)。

双向一对一主键关联(Bidirectional one-to-one (primary key association))

1.Domain

设计双向一对一关联Domain实例，Person对象和Address对象，人有一个地址，地址有一个人。

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public Address Address { get; set; }
}

public class Address
{
    public int Id { get; set; }
    public Person Person { get; set; }
    public string Street { get; set; }
    public int CivicNumber { get; set; }
}

2.ConfORM

使用ConfORM来配置Domain，使之编译生成我们需要的HbmMapping对象。其实这个代码和上面的一样：

[Test]
public void BidirectionalOneToOneMappingDemo1()
{
    //show how work with one-to-one and how ConfORM understands OOP
    var orm = new ObjectRelationalMapper();
    var mapper = new Mapper(orm);
    var entities = new[] { typeof(Person), typeof(Address) };
    //use the definition of table-to-class strategy class by class
    orm.TablePerClass(entities);
    // Defining relations
    orm.OneToOne<Person, Address>();
    //or orm.OneToOne<Address,Person>();
    // Show the mapping to the console
    var mapping = mapper.CompileMappingFor(entities);
    Console.Write(mapping.AsString());
}

3.Mapping

测试生成字符串：

4.原理

对于双向一对一关联，实际就是设置IOneToOneMapper，ConfORM会在IPatternsAppliersHolder的OneToOne和OneToOnePath集合中匹配对应模式适配器，即匹配到以下三个模式适配器，进行相应操作。

BidirectionalPrimaryKeyAssociationMasterOneToOneApplier：应用IOneToOneMapper.Cascade(Cascade.All)

BidirectionalOneToOneAssociationPoidApplier：应用IIdMapper.Generator(Generators.Foreign(BidirectionalOneToOneOrNull(subject.ReflectedType)))

BidirectionalPrimaryKeyAssociationSlaveOneToOneApplier：应用IOneToOneMapper.Constrained(true)

双向一对一外键关联(Bidirectional one-to-one (foreign key association))

Domain与双向一对一主键关联(Bidirectional one-to-one (primary key association))相同。

2.ConfORM

配置Domain，注意黑体

[Test]
public void BidirectionalOneToOneMappingDemo2()
{
    //show how work with one-to-one and how ConfORM understands OOP
    var orm = new ObjectRelationalMapper();
    var mapper = new Mapper(orm);
    var entities = new[] { typeof(Person), typeof(Address) };
    //use the definition of table-to-class strategy class by class
    orm.TablePerClass(entities);
    // Defining relations
    orm.ManyToOne<Person, Address>();
    orm.OneToOne<Address, Person>();
    // Show the mapping to the console
    var mapping = mapper.CompileMappingFor(entities);
    Console.Write(mapping.AsString());
}