NHibernate one-to-one 关系时 正确的xml写法和curd写法

parent.xml

 

<class name="parent" table="parent">

  <id name="Id" type="Int32" unsaved-value="null">
   <column name="id" length="4" sql-type="int" not-null="true" unique="true" />
   <generator class="identity" />
  </id>

  <one-to-one name="child" class="child" cascade="all" />

</class>

 

 

child.xml

 

<class name="child" table="child">
  <id name="Id" type="Int32" unsaved-value="null">
   <column name="id" length="4" sql-type="int" not-null="true" unique="true" />
      <generator class="foreign">
        <param name="property">parent</param>
      </generator>
  </id>

  <one-to-one name="parent" class="parent" constrained="true" />

</class>

 

 

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Save 存储的时候:

parent p = new parent();

child c = new child();

 

c.parent = p;

//p.child = c; //如果加上这个赋值,nhibernate会生成针对child表的update语句，因为是新生成记录，所以会出现“Unexpected row count: 0; expected: 1”错误提示。

 

session.Save(c); //将在parent,child表中各自生成1条记录

//session.Save(p); //将在parent表中生成一条记录,child表中没有记录

 

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Update 更新记录的时候

parent p = session.Load(parentId);

p.child.xxx = "xx";

 

//p.child = new child(); //这种方式更新子类，将会出现“Unexpected row count: 0; expected: 1”错误提示。new 出来的child还处于transient临时状态，替换p.child则会出错。

 

session.SaveOrUpdate(p); //这将同时更新parent和child表中的数据。

 

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Delete 删除记录的时候

parent p = session.Load(parentId);

session.Delete(p); //这样将同时删除parent和child表中的数据