NHibernate Quick Start Guide

1 实体类：

Code
using System;
using System.Collections.Generic;
using System.Text;

namespace NHibernate.Examples.QuickStart
{
    public class User
    {
        private string id;
        private string userName;
        private string password;
        private string emailAddress;
        private DateTime lastLogon;


        public User()
        {
        }

        public virtual string Id
        {
            get { return id; }
            set { id = value; }
        }

        public virtual string UserName
        {
            get { return userName; }
            set { userName = value; }
        }

        public virtual string Password
        {
            get { return password; }
            set { password = value; }
        }

        public virtual string EmailAddress
        {
            get { return emailAddress; }
            set { emailAddress = value; }
        }

        public virtual DateTime LastLogon
        {
            get { return lastLogon; }
            set { lastLogon = value; }
        }

    }

}

注意点：在属性之前要加上virtual关键字，否则运行时会报错。

2 map文件：

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
  <class name="NHibernate.Examples.QuickStart.User, NHibernate.Examples.QuickStart" table="users">
    <id name="Id" column="LogonId" type="String" length="20">
      <generator class="assigned" />
    </id>
    <property name="UserName" column="Name" type="String" length="40"/>
    <property name="Password" type="String" length="20"/>
    <property name="EmailAddress" type="String" length="40"/>
    <property name="LastLogon" type="DateTime"/>
  </class>
</hibernate-mapping>

注意点：如果对应的是.net framework2.0的版本，则

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">是2.2

其次是class name一定要写对。前面是要映射类的全称，后面是namespase,也就是Assembly的名称。

还有在生成操作中一定要选：嵌入的资源。

1）class: name属性指示了Post实体类的类名和所在的Assebmly的名称，NH将通过反射的方式找到所指示的实体类，关于.Net的反射的说明，请参考MSDN; table属性指示了该实体所对应的数据表的表名

2）property: 指示实体属性和数据列的如何映射。name为实体的属性名称，实体的该属性可以为public/private/protected，甚至是 internal；column指示了该属性对应的数据列，若实体属性名称和数据列名称相同（忽视大小写），可以省略；type指示了实体属性的.Net 数据类型，可以省略，NH可以自动转换；length只是对string类型的属性适用，指示了字符串的最大长度。

3）id: 指示主键。NH支持自动生成主键、数据库生成主键和手工赋值三种方式，我们这里手工赋值的方式，设定generator的class="assigned"。

3 hibernate.cfg.xml—配置文件

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section
      name="nhibernate" 
      type="System.Configuration.NameValueSectionHandler, System, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" 
    />
  </configSections>

  <nhibernate>
    <add 
      key="hibernate.connection.provider"
      value="NHibernate.Connection.DriverConnectionProvider"
    />
    <add
      key="hibernate.dialect"
      value="NHibernate.Dialect.MsSql2000Dialect"
    />
    <add
      key="hibernate.connection.driver_class"
      value="NHibernate.Driver.SqlClientDriver"
    />
    <add
      key="hibernate.connection.connection_string"
      value="Server=192.168.0.11;database=NHibernate;uid=sa;pwd=davey@citiz.net;"
    />
  </nhibernate>
</configuration>

注意：hibernate.connection.connection_string是数据库的连接字符串。

4 测试类：

using NHibernate;

using NHibernate.Cfg;

这两个是必须的。

        [SetUp]
        public void BuildNHibernate()
        {
            cfg = new Configuration();
            cfg.AddAssembly("NHibernate.Examples.QuickStart");
            factory = cfg.BuildSessionFactory();
            session = factory.OpenSession();

        }

在使用NHibernate进行数据库操作时需要以上这些东西。

3 Insert

Code
[Test]
        public void AddUser()
        {
            User newUser = new User();


            Configuration cfg = new Configuration();
            cfg.AddAssembly("NHibernate.Examples.QuickStart");
            ISessionFactory factory = cfg.BuildSessionFactory();
            ISession session = factory.OpenSession();
            ITransaction transaction = null;
            try
            {
                transaction = session.BeginTransaction();
                newUser.Id = "joe_cool";
                newUser.UserName = "Joseph Cool";
                newUser.Password = "abc123";
                newUser.EmailAddress = "joe@cool.com";
                newUser.LastLogon = DateTime.Now;
                // Tell NHibernate that this object should be saved
                session.Save(newUser);
                // commit all of the changes to the DB and close the ISession
                transaction.Commit();
                session.Close();
            }
            catch (HibernateException ex)
            {
                if (transaction != null) transaction.Rollback();
                throw ex;
            }
            finally
            {
                //关闭ISession
                session.Close();
            }
        }

4 update:

Code
        [Test]
        public void UpdateUser()
        {
            User joeCool = (User)session.Load(typeof(User), "joe_cool");
            Assert.AreEqual("Joseph Cool", joeCool.UserName);
            try
            {
                transaction = session.BeginTransaction();
                // set Joe Cool's Last Login property
                joeCool.LastLogon = DateTime.Now;

                // flush the changes from the Session to the Database
                session.Flush();
                // commit all of the changes to the DB and close the ISession
                transaction.Commit();
            }
            catch (HibernateException ex)
            {
                if (transaction != null) transaction.Rollback();
                throw ex;
            }
            finally
            {
                //关闭ISession
                session.Close();
            }

        }

5 select

根据主键查询

IList<User> userList = session.CreateCriteria(typeof(User)).List<User>();

有条件的查询

IList<User> recentUsers = session.CreateCriteria(typeof(User))
              .Add(Expression.Expression.Eq("UserName", "Joseph Cool"))
                .List<User>();

利用Hql语言查询

string hql = "  from User u where u.UserName = :Name ";
            IQuery query = session.CreateQuery(hql);
            query.SetString("Name","Joseph Cool");
            IList<User> recentUsers = query.List<User>();

6 一对多，多对多关系的查询

实体类：

Category

Code
   public class Category
    {
       private Guid _categoryId; 
       private string _name = string.Empty;
       private IList<Item> _items;

       public virtual Guid CategoryID
       {
          get { return this._categoryId; }
          set { this._categoryId = value; }
        }

       public virtual string Name
       {
         get { return this._name; }
         set { this._name = value; }
       }

        public virtual IList<Item> Items
        {
           get { return this._items; }
           set { this._items = value; }
        }
 
    
        public Category()
        {
            this._items = new List<Item>();
        }
     }

Item

Code
    public class Item
    {
       private Guid _itemId;
       private string _name = string.Empty;
       private Category _category;

       public virtual Guid ItemID
       {
        get { return this._itemId; }
        set { this._itemId = value; }
       }

       public virtual string Name
       {
           get { return this._name; }
           set { this._name = value; }
       }

        public virtual Category Category
        {
           get { return this._category; }
           set { this._category = value; }
        }
     }

类Category中包含类Item，是一对多的关系。

映射文件：

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
  <class name="NHibernate.Examples.OneToMany.Category, NHibernate.Examples.OneToMany" table="nh_categories">
    <id name="CategoryID" column="CategoryID" type="Guid" 
      unsaved-value="00000000-0000-0000-0000-000000000000">
      <generator class="guid" />
    </id>
    <property name="Name" type="string" length="50" />
    <bag name="Items" lazy="true" inverse="true" cascade= "all-delete-orphan">
    <key column="CategoryID" />
    <one-to-many class="NHibernate.Examples.OneToMany.Item, NHibernate.Examples.OneToMany" />
    </bag>
  </class>
  <class name="NHibernate.Examples.OneToMany.Item, NHibernate.Examples.OneToMany" table="nh_items">
    <id name="ItemID" column="ItemID" type="Guid" 
      unsaved-value="00000000-0000-0000-0000-000000000000">
      <generator class="guid" />
    </id>
    <property name="Name" type="string" length="50" />
    <many-to-one name="Category" class="NHibernate.Examples.OneToMany.Category, NHibernate.Examples.OneToMany" 
    column="CategoryID" />
  </class>
</hibernate-mapping>

其中在Category中指定了一对多的关系：

    <bag name="Items" lazy="true" inverse="true" cascade= "all-delete-orphan">
    <key column="CategoryID" />
    <one-to-many class="NHibernate.Examples.OneToMany.Item, NHibernate.Examples.OneToMany" />
</bag>

且指定了级联关系。
在类Item中指定了多对一的关系：

<many-to-one name="Category" class="NHibernate.Examples.OneToMany.Category, NHibernate.Examples.OneToMany" column="CategoryID" />

测试方法1（插入）：

Code
       [Test]
        public void TestCascadingSave()
        {
            // prepare test objects
            Category expectedCategory = new Category();
            expectedCategory.Name = "category" + System.Environment.TickCount.ToString();
            for (int i = 0; i < 10; i++)
            {
                Item item = new Item();
                item.Name = "item" + System.Environment.TickCount.ToString();
                item.Category = expectedCategory;

                expectedCategory.Items.Add(item);
            }
            // save objects in a all-cascading way
            // note: cascading option should at least set as "all" in objects.hbm.xml
            transaction = session.BeginTransaction();
            try
            {
                session.SaveOrUpdate(expectedCategory);
                transaction.Commit();
            }
            catch
            {
                transaction.Rollback();
                throw;
            }
            // that works?
            Category actualCategory =
                session.Get(typeof(Category), expectedCategory.CategoryID) as Category;
            Assert.IsNotNull(actualCategory);
            Assert.AreEqual(expectedCategory.Items.Count, actualCategory.Items.Count);
        }

测试方法2（级联删除）：

Code
        [Test]
        public void TestCascadingDelete()
        {
            Category expectedCategory = 
              session.CreateCriteria(typeof(Category)).List()[0] as Category;
            // remove category from the repository
            transaction = session.BeginTransaction();
            try
            {
                session.Delete(expectedCategory);
                transaction.Commit();
            }
            catch
            {
                transaction.Rollback();
                throw;
            }
            // that works?
            Assert.AreEqual(0, session.CreateCriteria(typeof(Category)).List().Count);
            Assert.AreEqual(0, session.CreateCriteria(typeof(Item)).List().Count);
        }