Castle.ActiveRecord 学与练[3]

    Castle.ActiveRecord引入了特性映射这个概念,使用Attribute来代替.hbm.xml文件,从而更加清晰的呈现出了实体类跟数据库表之间的关系,使持久化的数据操作更加简单,易用.
    下面就让咱们一起来通过一个完整的实例了解一下Castle.ActiveRecord的Attribute.

    我们先来创建三个数据库表,接下来的文章练习都是围绕着这三个表来操作,便于演示一对多,多对一及相应的级联更新,删除等操作.

CREATE TABLE [dbo].[role](
    [roleid] [int] IDENTITY(1,1) NOT NULL,
    [name] [nvarchar](50) COLLATE Chinese_PRC_CI_AS NOT NULL,
    [permissionlevel] [int] NOT NULL DEFAULT (1),
    [inserttimestamp] [datetime] NOT NULL DEFAULT (getdate()),
    [updatetimestamp] [datetime] NOT NULL DEFAULT (getdate()),
 CONSTRAINT [PK_role] PRIMARY KEY CLUSTERED 
(
    [roleid] ASC
) ON [PRIMARY],
 CONSTRAINT [UC_role_name] UNIQUE NONCLUSTERED 
(
    [name] ASC
) ON [PRIMARY]
) ON [PRIMARY]
GO

CREATE TABLE [dbo].[users](
    [LogonID] [int] IDENTITY(1,1) NOT NULL,
    [LogonName] [varchar](40) COLLATE Chinese_PRC_CI_AS NULL,
    [Password] [varchar](20) COLLATE Chinese_PRC_CI_AS NULL,
    [EmailAddress] [varchar](40) COLLATE Chinese_PRC_CI_AS NULL,
    [LastLogon] [datetime] NULL,
 CONSTRAINT [PK_Users] PRIMARY KEY CLUSTERED 
(
    [LogonID] ASC
) ON [PRIMARY]
) ON [PRIMARY]
GO

CREATE TABLE [dbo].[userrole](
    [userroleid] [int] IDENTITY(1,1) NOT NULL,
    [userid] [int] NOT NULL,
    [roleid] [int] NOT NULL,
 CONSTRAINT [PK_userrole] PRIMARY KEY CLUSTERED 
(
    [userroleid] ASC
) ON [PRIMARY]
) ON [PRIMARY]

GO
ALTER TABLE [dbo].[userrole]  WITH CHECK ADD  CONSTRAINT [FK_user_userid] FOREIGN KEY([userid])
REFERENCES [dbo].[users] ([LogonID])
GO
ALTER TABLE [dbo].[userrole]  WITH CHECK ADD  CONSTRAINT [FK_userrole_role_roleid] FOREIGN KEY([roleid])
REFERENCES [dbo].[role] ([roleid])
GO

第一部分:特性介绍
ActiveRecordAttribute:
--------------------------------------------------------------------------------------------------------------------------------------

	Name	Description
	BatchSize	From NHibernate documentation: Specify a "batch size" for fetching instances of this class by identifier.
	DiscriminatorColumn	Gets or sets the Discriminator column for a table inheritance modeling 为表设置一个识别器字段
	DiscriminatorType	Gets or sets the column type (like string or integer) for the discriminator column 为识别器字段设置一个字段类型(例如:String或者Int)
	DiscriminatorValue	Gets or sets the value that represents the target class on the discriminator column 为识别器字段设置一个可以描述目标类的值
	DynamicInsert	From NHibernate documentation: Specifies that INSERT SQL should be generated at runtime and contain only the columns whose values are not null.
	DynamicUpdate	From NHibernate documentation: Specifies that UPDATE SQL should be generated at runtime and contain only those columns whose values have changed.
	Lazy	Enable lazy loading for the type 打开延迟加载
	LazySpecified	Gets a value indicating whether explicit lazy behavior was specified. If explicit lazy behavior was not specified, it goes to the configuration to decide if the type should be lazy or not.
	Locking	From NHibernate documentation: Determines the optimistic locking strategy.
	Mutable	From NHibernate documentation: Specifies that instances of the class are (not) mutable.
	Persister	From NHibernate documentation: Specifies a custom IEntityPersister.
	Polymorphism	From NHibernate documentation: Determines whether implicit or explicit query polymorphism is used.
	Proxy	Associates a proxy type with the target type
	Schema	Gets or sets the schema name associated with the type 设置概要的信息
	SelectBeforeUpdate	From NHibernate documentation: Specifies that NHibernate should never perform an SQL UPDATE unless it is certain that an object is actually modified. In certain cases (actually, only when a transient object has been associated with a new session using update()), this means that NHibernate will perform an extra SQL SELECT to determine if an UPDATE is actually required.
	Table	Gets or sets the table name associated with the type 表名，类名与表名相同可为空
	UseAutoImport	From NHibernate documentation: The auto-import attribute lets us use unqualified class names in the query language, by default. The assembly and namespace attributes specify the assembly where persistent classes are located and the namespace they are declared in.
	Where	SQL condition to retrieve objects 指定一个附加SQL的WHERE子句

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PrimaryKeyAttribute:
--------------------------------------------------------------------------------------------------------------------------------------

	Name	Description
	Column	Gets or sets the column name 设置字段名
	ColumnType	Gets or sets the type of the column. 设置字段类型
	CustomGenerator	Gets or sets the custom generator. The generator must implement IIdentifierGenerator 设置一个自定义的生成器．这个生成器必要实现IIdentifierGenerator接口
	Generator	Gets or sets the generator. 设置一个生成器，是一个.NET类的名字，用来为该持久化类的实例生成惟一的标识．
	Length	Gets or sets the length of values in the column 设置字段长度
	Params	Comma separated value of parameters to the generator 用parameters来为生成器配置参数或者初始化参数．
	SequenceName	Gets or sets the name of the sequence. 当指定主键的生成方式为Sequence时，序列的名称 当指定主键的生成方式为Sequence时，Sequence的名称．
	UnsavedValue	Gets or sets the unsaved value. 设置该实例未保存时的值

--------------------------------------------------------------------------------------------------------------------------------------

PrimaryKeyType
--------------------------------------------------------------------------------------------------------------------------------------

	Name	Description
	Identity	Use Identity column (auto number) Note: This force an immediate call to the DB when Create() is called 对DB2,MySQL, MS SQL Server, Sybase和HypersonicSQL的内置标识字段提供支持，生成自增的整型 当Create() 方法执行时，便会触发数据库表自增类型字段自增．
	Sequence	Use a sequence 序列
	HiLo	Use the HiLo algorithm to get the next value  高低位,使用一个高/低位算法来高效的生成Int64, Int32 或者 Int16类型的标识符。
	SeqHiLo	Use a sequence and a HiLo algorithm - better performance on Oracle 使用序列的高低位,使用一个高/低位算法来高效的生成Int64, Int32 或者 Int16类型的标识符，给定一个数据库序列（sequence)的名字。
	UuidHex	Use the hex representation of a unique identifier 用一个System.Guid和它的ToString(string format)方法生成字符串类型的标识符。
	UuidString	Use the string representation of a unique identifier 用一个新的System.Guid产生一个byte[] ，把它转换成字符串。
	Guid	Generate a Guid for the primary key Note: You should prefer using GuidComb over this value. 用一个新的System.Guid 作为标识符。
	GuidComb	Generate a Guid in sequence, so it will have better insert performance in the DB. 用Jimmy Nilsso的一个算法产生一个新的System.Guid。
	Native	Use an identity or sequence if supported by the database, otherwise, use the HiLo algorithm 根据底层数据库的能力选择 identity, sequence 或者 hilo中的一个。默认值。
	Assigned	The primary key value is always assigned. Note: using this you will lose the ability to call Save(), and will need to call Create() or Update() explicitly. 让应用程序在自己为对象分配一个标示符。
	Foreign	This is a foreign key to another table 外键
	Counter	Returns a Int64 constructed from the system time and a counter value. 返回一个INT64类型的系统时间和一个记数器值．
	Increment	Returns a Int64, constructed by counting from the maximum primary key value at startup. 主键最大值加１
	Custom	A custom generator will be provided. See CustomGenerator

--------------------------------------------------------------------------------------------------------------------------------------

PropertyAttribute:
--------------------------------------------------------------------------------------------------------------------------------------

	Name	Description
	Check	From NHibernate documentation: create an SQL check constraint on either column or table 约束
	Column	Gets or sets the column name 设置字段名
	ColumnType	Gets or sets the type of the column. 设置字段类型
	Formula	Gets or sets the formula used to calculate this property 一个SQL表达式，定义了这个计算（computed） 属性的值。计算属性没有和它对应的数据库字段。
	Index	From NHibernate documentation: specifies the name of a (multi-column) index
	Insert	Set to false to ignore this property when inserting entities of this ActiveRecord class. 表明在用于INSERT的SQL语句中是否包含这个字段。默认为true
	Length	Gets or sets the length of the property (for strings - nvarchar(50) ) 字段长度
	NotNull	Gets or sets a value indicating whether this property allow null. 是否允许为空
	SqlType	From NHibernate documentation: overrides the default column type 重写默认的字段类型．
	Unique	Gets or sets a value indicating whether this PropertyAttribute is unique. 是否允许重复．
	UniqueKey	From NHibernate documentation: A unique-key attribute can be used to group columns in a single unit key constraint.
	Update	Set to false to ignore this property when updating entities of this ActiveRecord class. 表明在用于UPDATE的SQL语句中是否包含这个字段。默认为true

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第二部分:源码讲解
ActiveRecordAttribute:
对于ActiveRecordAttribute来说,其中比较重要的参数就是Table了,用它来确定这个实体指向哪个数据库表.不填表示类实体名与数据库表名相同.

    [ActiveRecord(Table = "Users",Schema = "Training",Where = "1 = 1")]
    public class Users : ActiveRecordBase
    {
     
          }

PrimaryKeyAttribute:
对于PrimaryKeyAttribute来说,顾名思义此特性是为了设置主键而设计的,其中PrimaryKeyType为大家提供了多种类型可以应付各种情况,详见上面表格.

[PrimaryKey(PrimaryKeyType.Identity, Column = "LogonID",ColumnType = "Int32")]
        public int Id
        {
            get { return _id; }
            set { _id = value; }
              }

PropertyAttribute:
对于PropertyAttribute来说Column参数相对重要,用它来确定属性对应数据库表中哪个字段,如果为空则字段名与属性名相同.

        [Property(Column = "Name", NotNull = true, ColumnType = "String")]
        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

    实体类源码下载

    最近真是太忙了,SAP一直在我们周围转啊转,终于到了要上线的地步了.
    写了这一些,先给大家看看吧,下一篇会在数据的操作上向大家演示Castle.ActiveRecord的奇妙之处,以完成Castle的Castle.ActiveRecord部分,敬请关注. 

     谢谢Terrylee老师的教程对我的帮助.
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