NHibernate使用入门(十二)

双向一对多关联映射

Customer.hbm.xml映射文件

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-lazy="false"
                    assembly="NtestRelationship"
                   namespace="NtestRelationship.Entities"

                   >
  <class name="Customer">
    <id type="int" name="Id">
      <column name="Id" />
      <generator class="identity"></generator>
    </id>
    <property name="FirstName"/>
    <property name="LastName"/>

    <bag name="Orders" cascade="all" inverse="true" lazy="false" fetch="join">      
      <key column="customerId"
          not-null="true"/>
      <one-to-many class="Order"/>
    </bag>

  </class>
</hibernate-mapping>

Order.hbm.xml映射文件

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-lazy="false"
                    assembly="NtestRelationship"
                   namespace="NtestRelationship.Entities"

                   >
  <class name="Order" table="Orders">
    <id type="int" name="Id">
      <column name="Id" />
      <generator class="identity"></generator>
    </id>
    <property name="Value"/>

    <!--双向映射维护-->
    <many-to-one name="Customer" column="customerId" not-null="true"/>

  </class>
</hibernate-mapping>

OneToManyRelationBidirectional类:

 public class OneToManyRelationBidirectional 
    {
        private readonly ISessionFactory sessionFactory = new Configuration().Configure().BuildSessionFactory();
        protected object CustomerId = 1;
        public void AddOrderToCustomer()
        {
            using (var session = sessionFactory.OpenSession())
            using (var transaction = session.BeginTransaction())
            {
                Customer customer = session.Get<Customer>(CustomerId);

                customer.Orders.Add(new Order() { Value = 3, Customer = customer });
                customer.Orders.Add(new Order() { Value = 5, Customer = customer });
                customer.Orders.Add(new Order() { Value = 13, Customer = customer });

                session.Save(customer);

                transaction.Commit();
            }

            using (var session = sessionFactory.OpenSession())
            {
                Customer customer = session.Get<Customer>(CustomerId);

                Console.WriteLine("customer.Orders NotBeEmpty IS :" + customer.Orders.Count);
                Console.WriteLine("customer.Orders[0].Customer NotBeNull IS :" + customer.Orders[0].Customer!=null);
            }
        }
    }

主程序:

class Program
    {
        static void Main(string[] args)
        {
            OneToManyRelationBidirectional otmr = new OneToManyRelationBidirectional();
            otmr.AddOrderToCustomer();
            Console.ReadKey();
        }
    }

运行结果: