nhibernate 表之间的几种关系不易把握,现根据个人学习,总结如下,共同学习,提高,
完整代码参见我的资源[NHibernateTestExampleforSqlServer20110109]
若有错误,请指出,
不甚感谢!
a. 实体:
public class Parent
{
public Parent()
{
children = new HashedSet();
}
private Guid id;
private ISet children;
public virtual Guid Id
{
get { return id; }
set { id = value; }
}
public virtual ISet Children
{
get { return children; }
set { children = value; }
}
}
public class Child
{
public Child()
{
}
public virtual Guid Id { get; set; }
public virtual string Name { get; set; }
}
b. 映射
<class name="Parent">
<id name="Id">
<generator class="guid" />
</id>
<!--完全由parent来控制,因为引入了第三个表ChildSet,所以设置cascade-->
<!--<set name="Children" table="ChildSet" inverse="false" lazy="true" cascade="all">-->
<!--由child来控制,只保存了parent表-->
<!--<set name="Children" table="ChildSet" inverse="true" lazy="true" >-->
<!--将保存parent,child表,不保存childSet表-->
<set name="Children" table="ChildSet" inverse="true" lazy="true" cascade="all" >
<key column="parent_id"/>
<many-to-many class="Child" column="child_id" />
</set>
</class>
<class name="Child">
<id name="Id">
<generator class="guid" />
</id>
<property name="Name"/>
</class>
c. 测试代码:
[Test]
public void CreateInitialDataManytoMany()
{
using (ISession session = _sessionFactory.OpenSession())
using (ITransaction transaction = session.BeginTransaction())
{
Parent p1 = new Parent();
Parent p2 = new Parent();
Child c1 = new Child();
c1.Name = "c1";
Child c2 = new Child();
c2.Name = "c2";
//one parent two child
p1.Children.Add(c1);
p1.Children.Add(c2);
//two parent one child
p2.Children.Add(c1);
session.Save(p1);
session.Save(p2);
transaction.Commit();
}
}
d. 总结:
Many-to-manny 引入了第三个表childSet,注意cascade和inverse设置不同所产生的效果
