• 01-03-02-1【Nhibernate (版本3.3.1.4000) 出入江湖】CRUP操作--cascade 级联相关


    要点:

    1.

    <!--双向关联时要用:
    inverse:由子表来维护关系,cascade:级联的关系 如果没有这个设置,
    插入Customer成功(即使现在Order插入Order抛异常,这时产生了垃圾数据,
    好的做法是用事务两者都能插入,避免垃圾数据的产生-->
    <!--经测试:只需要在主表配置cascade="all",而子表不用配置cascade="all",
    当删除主表实体时,子表的级联实体也会被删除-->
    <!--cascade有4种??是吗??,分别表示级联操作的4种操作:
    cascade = "none": 不能执行操作(有子时不给删父),经测试,为none时,添加父时没有自动添加子
    cascade = "all" : 1.级联(删父时删子),经测试,为all时,添加父时自动添加子,
    2.经测试,当设置cascade = "all",MS SQL Server设置删除和更新操作虽然设置为:不执行操作,却被覆盖为联级
    cascade = "null": (删父时子设置为null),但经测试Nhibernate不支持这个值
    cascade = "???": 删父时子设置为默认值-->

    <set name="Orders" table="Order" generic="true"
    inverse="true" cascade="all">
    
    <key column="CustomerId" foreign-key="FK_CustomerOrders"/>
    <one-to-many class="Model.Order,Model"/>
    </set>


    2

    Custmer.cs

     1 using Iesi.Collections.Generic;
     2 using System;
     3 using System.Linq;
     4 using System.Text;
     5 
     6 namespace Model
     7 {
     8     public class Customer
     9     {
    10         public virtual int CustomerId{ get; set; }
    11         public virtual String FirstName { get; set; }
    12         public virtual String LastName { get; set; }
    13 
    14         public virtual int Age { get; set; }
    15         public virtual int Version { get; set; }
    16 
    17         private ISet<Order> _orders = new HashedSet<Order>();
    18         public virtual ISet<Order> Orders
    19         {
    20             get { return _orders; }
    21             set { this._orders = value; }
    22         }
    23 
    24     }
    25 }

    Customer.hbm.xml

     1 <?xml version="1.0" encoding="utf-8" ?>
     2 <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" 
     3                    namespace="Model" 
     4                    assembly="Model" 
     5                    default-lazy="true">
     6   
     7   <class name="Model.Customer, Model"
     8          discriminator-value="0">
     9     <!--unsaved-value="0" 主键表中不需要定义,而是需要在子表中定义-->
    10     <id name="CustomerId"
    11         column="CustomerId"
    12         type="Int32" 
    13         unsaved-value="0">
    14       <generator class="native" />
    15       <!-- unsaved-value used to be null and generator was increment in h2.0.3 -->
    16     </id>
    17 
    18     <!--version标签必须放在Id后面,否则出错-->
    19     <version name="Version"/>
    20 
    21     <property name="FirstName" >
    22       <column name="Firstname" length="50" not-null="true"/>
    23     </property>
    24 
    25     <property name="LastName" type="String">
    26       <column name="Lastname"/>
    27     </property>
    28 
    29     <property name="Age" type="int">
    30       <column name="Age"/>
    31     </property>
    32 
    33     <!--双向关联时要用:
    34          inverse:由子表来维护关系,cascade:级联的关系 如果没有这个设置,
    35         插入Customer成功(即使现在Order插入Order抛异常,这时产生了垃圾数据,
    36         好的做法是用事务两者都能插入,避免垃圾数据的产生-->
    37     <!--经测试:只需要在主表配置cascade="all",而子表不用配置cascade="all"38     当删除主表实体时,子表的级联实体也会被删除-->
    39     <!--cascade有4种??是吗??,分别表示级联操作的4种操作:
    40       cascade = "none": 不能执行操作(有子时不给删父),经测试,为none时,添加父时没有自动添加子
    41       cascade = "all" : 1.级联(删父时删子),经测试,为all时,添加父时自动添加子,
    42                         2.经测试,当设置cascade = "all",MS SQL Server设置删除和更新操作虽然设置为:不执行操作,却被覆盖为联级
    43       cascade = "null": (删父时子设置为null),但经测试Nhibernate不支持这个值
    44       cascade = "???": 删父时子设置为默认值-->
    45     <set name="Orders" table="Order" generic="true"
    46           inverse="true" cascade="all">
    47 
    48       <key column="CustomerId" foreign-key="FK_CustomerOrders"/>
    49       <one-to-many class="Model.Order,Model"/>
    50     </set>
    51   </class>
    52 </hibernate-mapping>

    Order.cs

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace Model
    {
        public class Order
        {
            public virtual int OrderId { get; set; }
            public virtual DateTime OrderDate { get; set; }
            public virtual Customer Customer { get; set; }
    
            public virtual int Version { get; set; }
        }
    }

    Order.hbm.xml

    <?xml version="1.0" encoding="utf-8" ?>
    <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" 
                       namespace="Model" 
                       assembly="Model" 
                       default-lazy="true">
      
      <!--table ="[Order]"因为Order是SQL关键字,表名如果不添加中括号[]会抛异常-->
      <!--unsaved-value="0" 主键表中不需要定义,而是需要在子表中定义
          unsaved-value id的类型是对象类型(如Int32等)unsaved-value不用显示标出来,因为unsaved-value默认值是null
      unsaved-value默认值是null,
      作用是:用于判断实体对象是新new的内存对象,还是应经持久化的对象,Nhibernate会从数据库中去获取
      该实体对象的Id与unsaved-value的值比较(如果持久化,id不等于null,当然也就不等于默认值为unsaved-value):
      
      1.实体对象的Id与unsaved-value的值,相等,说明调用Save()添加,
      2.实体对象的Id与unsaved-value的值,不相等相等,调用Update(),
              
         并在如果
      -->
      <class name="Model.Order, Model" 
             table ="[Order]"
             discriminator-value="0" lazy="false">
        <id name="OrderId" 
            column="OrderId" 
            type="Int32" 
            unsaved-value="0">
          <generator class="native" />
          <!-- unsaved-value used to be null and generator was increment in h2.0.3 -->
        </id>
        
        <!--version标签必须放在Id后面,否则出错-->
        <!--<version name="Version"/>-->
       
        <property name="OrderDate"  type="DateTime"  not-null="true">
          <column name="OrderDate" />
        </property>
    
        <many-to-one name="Customer" not-null="true">
          <column name="CustomerId" />
        </many-to-one>
        
      </class>
    </hibernate-mapping>
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  • 原文地址:https://www.cnblogs.com/easy5weikai/p/3746939.html
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