在本章中，我们将介绍映射数据类型.映射实体很简单，实体类总是使用< class>，< subclass>和< joined-subclass> 映射元素映射到数据库表.值类型需要更多，这是需要映射类型的地方.
NHibernate能够映射各种各样的数据类型.以下是支持的最常见数据类型列表.
| 映射类型 | .NET类型 | System.Data.DbType |
|---|---|---|
| Int16 | System.Int16 | DbType.Int16 |
| Int32 | System.Int32 | DbType.Int32 |
| Int64 | System.Int64 | DbType.Int64 |
| Single | System.Single | DbType.Single |
| Double | System.Double | DbType.Double |
| 十进制 | System.Decimal | DbType.Decimal |
| String | System.String | DbType.String |
| AnsiString | System.String | DbType.AnsiString |
| 字节 | System.Byte | DbType .Byte |
| Char | System.Char | DbType.StringFixedLength-一个字符 |
| AnsiChar | 系统. Char | DbType.AnsiStringFixedLength-one character |
| Boolean | System.Boolean | DbType.Boolean |
| Guid | System.Guid | DbType.Guid |
| PersistentEnum | System.Enum(枚举) | 基础值的DbType |
| TrueFalse | System.Boolean | DbType.AnsiStringFixedLength-"T"或'F' |
| YesNo | System.Boolean | D. bType.AnsiStringFixedLength-'Y'或'N' |
| DateTime | DateTime | DbType.DateTime-忽略毫秒 |
| Ticks | System.DateTime | DbType.Int64 |
| TimeSpan | System.TimeSpan | DbType.Int64 |
| Timestamp | System.DateTime | DbType.DateTime-具体与数据库支持 |
| Binary | System.Byte [] | DbType.Binary |
| BinaryBlob | System.Byte [] | DbType.Binary |
| StringClob | System.String | DbType.String |
| Serializable | 任何系统.用SerializableAttribute标记的对象 | DbType.Binary |
| Cu ltureInfo | System.Globalization.CultureInfo | DbType.String-文化的五个字符 |
| Type | System.Type | 持有程序集限定名称的DbType.String |
上面给出的表格详细解释了下面提到的指针.
从简单的数字类型到字符串的所有内容，可以使用 varchars，chars 等以各种方式映射，以及字符串blob和所有种类数据库支持的类型.
它还可以将布尔映射到使用零和1的字段，字符字段包含true，false或T和F.
有多种方法可以定义映射到后端的方式，即数据库中的布尔值./p>
我们可以处理 DateTime 的映射，包括和排除时区偏移，日光avings time等.
我们还可以映射枚举;我们可以将这些映射到字符串或它们的基础数值.
让我们看一个我们有相同的简单示例数据库和Student类中的属性名称.
现在让我们将学生类中的FirstMidName更改为FirstName，我们不会更改FirstMidName列，但我们会看到如何告诉NHibernate知道进行这种转换.以下是更新的学生课程.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace NHibernateDemoApp {
class Student {
public virtual int ID { get; set; }
public virtual string LastName { get; set; }
public virtual string FirstName { get; set; }
}
}这是NHibernate映射文件的实现.
<?xml version = "1.0" encoding = "utf-8" ?> <hibernate-mapping xmlns = "urn:nhibernate-mapping-2.2" assembly = "NHibernateDemoApp" namespace = "NHibernateDemoApp"> <class name = "Student"> <id name = "ID"> <generator class = "native"/> </id> <property name = "LastName"/> <property name = "FirstName" column = "FirstMidName" type = "String"/> </class> </hibernate-mapping>
在此示例中，假设FirstName字段是.NET字符串，FirstMidName列是 SQL nvarchar .现在告诉NHibernate如何执行此转换，将名称设置为等于 FirstName ，列等于 FirstMidName 并指定等于String的映射类型，这适合于此特定转换.
以下是 Program.cs 文件实现.
using HibernatingRhinos.Profiler.Appender.NHibernate;
using NHibernate.Cfg;
using NHibernate.Dialect;
using NHibernate.Driver;
using System;
using System.Linq;
using System.Reflection;
namespace NHibernateDemoApp {
class Program {
static void Main(string[] args) {
NHibernateProfiler.Initialize();
var cfg = new Configuration();
String Data Source = asia13797\\sqlexpress;
String Initial Catalog = NHibernateDemoDB;
String Integrated Security = True;
String Connect Timeout = 15;
String Encrypt = False;
String TrustServerCertificate = False;
String ApplicationIntent = ReadWrite;
String MultiSubnetFailover = False;
cfg.DataBaseIntegration(x = > { x.ConnectionString = "Data Source +
Initial Catalog + Integrated Security + Connect Timeout + Encrypt +
TrustServerCertificate + ApplicationIntent + MultiSubnetFailover";
x.Driver<SqlClientDriver>();
x.Dialect<MsSql2008Dialect>();
x.LogSqlInConsole = true;
});
cfg.AddAssembly(Assembly.GetExecutingAssembly());
var sefact = cfg.BuildSessionFactory();
using (var session = sefact.OpenSession()) {
using (var tx = session.BeginTransaction()) {
var students = session.CreateCriteria<Student>().List<Student>();
Console.WriteLine("\nFetch the complete list again\n");
foreach (var student in students) {
Console.WriteLine("{0} \t{1} \t{2}", student.ID, student.FirstName,
student.LastName);
}
tx.Commit();
}
Console.ReadLine();
}
}
}
}现在，当您运行应用程序时，您将看到以下内容输出.
NHibernate: SELECT this_.ID as ID0_0_, this_.LastName as LastName0_0_, this_.FirstMidName as FirstMid3_0_0_ FROM Student this_ Fetch the complete list again 3 Allan Bommer 4 Jerry Lewis
正如你所看到的那样它已将不同的属性名称映射到数据库中的列名.
让我们看看另一个示例，其中我们将在枚举的Student类中添加另一个属性类型.这是Student类的实现.
using System;
using System.Collections.Generic;
using System.Linq; using System.Text;
using System.Threading.Tasks;
namespace NHibernateDemoApp {
class Student {
public virtual int ID { get; set; }
public virtual string LastName { get; set; }
public virtual string FirstName { get; set; }
public virtual StudentAcademicStanding AcademicStanding { get; set; }
}
public enum StudentAcademicStanding {
Excellent,
Good,
Fair,
Poor,
Terrible
}
}正如您所看到的，枚举具有各种不同的值，例如，优秀，良好，公平，差和可怕.
跳转到映射文件，您可以看到映射文件中列出了这些属性中的每一个，包括新添加的 AcademicStanding 属性.
<?xml version = "1.0" encoding = "utf-8" ?> <hibernate-mapping xmlns = "urn:nhibernate-mapping-2.2" assembly = "NHibernateDemoApp" namespace = "NHibernateDemoApp"> <class name = "Student"> <id name = "ID"> <generator class = "native"/> </id> <property name = "LastName"/> <property name = "FirstName" column = "FirstMidName" type = "String"/> <property name = "AcademicStanding"/> </class> </hibernate-mapping>
现在我们还需要更改数据库，所以转到SQL Server对象资源管理器并右键单击数据库并选择新查询...选项.
它将打开查询编辑器然后指定以下查询.
DROP TABLE [dbo].[Student] CREATE TABLE [dbo].[Student] ( [ID] INT IDENTITY (1, 1) NOT NULL, [LastName] NVARCHAR (MAX) NULL, [FirstMidName] NVARCHAR (MAX) NULL, [AcademicStanding] NCHAR(10) NULL, CONSTRAINT [PK_dbo.Student] PRIMARY KEY CLUSTERED ([ID] ASC) );
此查询将首先删除现有的学生表，然后创建一个新表.
Clcik，如上所示.成功执行查询后，您会看到一条消息.
展开数据库和表下拉列表，然后右键单击Student表并选择View Designer.
现在，您将看到新创建的表，它还具有新属性AcademicStanding .
让我们添加两条记录，如下所示 Program.cs 文件.
using HibernatingRhinos.Profiler.Appender.NHibernate;
using NHibernate.Cfg;
using NHibernate.Dialect;
using NHibernate.Driver;
using System;
using System.Linq;
using System.Reflection;
namespace NHibernateDemoApp {
class Program {
static void Main(string[] args) {
NHibernateProfiler.Initialize();
var cfg = new Configuration();
String Data Source = asia13797\\sqlexpress;
String Initial Catalog = NHibernateDemoDB;
String Integrated Security = True;
String Connect Timeout = 15;
String Encrypt = False;
String TrustServerCertificate = False;
String ApplicationIntent = ReadWrite;
String MultiSubnetFailover = False;
cfg.DataBaseIntegration(x = > { x.ConnectionString = "Data Source +
Initial Catalog + Integrated Security + Connect Timeout + Encrypt +
TrustServerCertificate + ApplicationIntent + MultiSubnetFailover";
x.Driver<SqlClientDriver>();
x.Dialect<MsSql2008Dialect>();
});
cfg.AddAssembly(Assembly.GetExecutingAssembly());
var sefact = cfg.BuildSessionFactory();
using (var session = sefact.OpenSession()) {
using (var tx = session.BeginTransaction()) {
var student1 = new Student {
ID = 1,
FirstName = "Allan",
LastName = "Bommer",
AcademicStanding = StudentAcademicStanding.Excellent
};
var student2 = new Student {
ID = 2,
FirstName = "Jerry",
LastName = "Lewis",
AcademicStanding = StudentAcademicStanding.Good
};
session.Save(student1);
session.Save(student2);
var students = session.CreateCriteria<Student>().List<Student>();
Console.WriteLine("\nFetch the complete list again\n");
foreach (var student in students) {
Console.WriteLine("{0} \t{1} \t{2} \t{3}", student.ID,
student.FirstName, student.LastName, student.AcademicStanding);
}
tx.Commit();
}
Console.ReadLine();
}
}
}
}现在让我们运行你的应用程序，你会看到以下输出在你的控制台窗口.
Fetch the complete list again 1 Allan Bommer Excellent 2 Jerry Lewis Good
现在让我们通过右键单击学生表来查看数据库.
选择查看数据，您将在学生表中看到两条记录，如以下屏幕截图所示.
您可以看到添加了两条记录，Allan拥有AcademicStanding 0和Jerry已经AcademicStanding 1.这是因为在.Net中，默认情况下第一个枚举值为0，如果你看 StudentAcademicStanding ，这是优秀的.然而，在Student.cs文件中，Good是第二个，因此它的值为1.
