一。 在Jasper中，针对数据定义的具体情形，一般有三种方案：
1.数据库中的数据定义与应用中的对象模型有一一对应的关系，那么不用做任何改动，直接调用默认的API即可
2.如果数据库中的数据定义与应用中的对象模型结构类同，但名称有所不同，则可以通过Jasper的命名服务（NameService）来做映射
譬如，我想把我以前的例子中的User->Yonghu,Post->Tiezi, UserName->Zhanghao,我可以这么做
>>> import clr
>>> import System
>>> from System import *
>>>
>>> clr.AddReference("Microsoft.Jasper.CTP")
>>> from Microsoft.Jasper import *
要使用NameService，需要引进这个程序集：
>>> clr.AddReference("System.Data.Entity.Design.CTP")
>>> from System.Data.Entity.Design import *
生成一个命名服务对象，在其中的PropertyNameMap和ClassNameMap添加映射,如果需要的话，还可以添加成员变量，方法名，以及参数名的映射
>>> nameService = NameService()
>>> nameService.BaseNameService = NameService.Default
>>> nameService.PropertyNameMap.AddNameMapping("UserName", "Zhanghao")
>>> nameService.ClassNameMap.AddNameMapping("Users", "Yonghus")
>>> nameService.ClassNameMap.AddNameMapping("Posts", "Tiezis")
>>>
>>> connStr = "Provider='System.Data.SqlClient';Provider Connection String='Initial Catalog=Jasper;Data Source=.\SQLExpress;Integrated Security=True;';Generate Default EDM=True"
将命名服务对象作为CreateDynamicContext的第二个参数
>>> ctx = DynamicContext.CreateDynamicContext(connStr,nameService)
>>>
Users不存在了，已经被换掉了
>>> u = ctx.Users[0]
Traceback (most recent call last):
File , line 0, in <string>##45
File , line 0, in _stub_##46
AttributeError: couldn't find member Users
变成了Yonghus和Tiezis:
>>> dir(ctx)
['AcceptAllChanges', 'AddObject', 'Attach', 'AttachTo', 'CodeRepresentation', 'Connection', 'ContextSaved', 'ContextSaving', 'CreateDynamicContext', 'CreateKey', 'CreateQuery', 'DefaultContainerName', 'DelAttrMethod', 'DeleteObject', 'Detach', 'Dispose', 'Equals', 'ExecuteDirectQuery', 'ExecuteFunction', 'ExecuteNativeMethod', 'Finalize', 'GetAttribute', 'GetHashCode', 'GetObjectByKey', 'GetQuery', 'GetType', 'Hash', 'MemberwiseClone', 'MetadataWorkspace', 'ObjectStateManager', 'PythonToString', 'QueryTimeout', 'Reduce', 'ReferenceEquals', 'Refresh', 'SaveChanges', 'SetAttrMethod', 'Tiezis', 'ToString', 'TryGetObjectByKey', 'TryGetQuery', 'Yonghus', '__class__', '__delattr__', '__doc__', '__entityHelper', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', '_tiezis', '_yonghus', 'add_ContextSaved', 'add_ContextSaving', 'get_Connection', 'get_DefaultContainerName', 'get_MetadataWorkspace', 'get_ObjectStateManager', 'get_QueryTimeout', 'get_Tiezis', 'get_Yonghus', 'remove_ContextSaved', 'remove_ContextSaving', 'set_DefaultContainerName', 'set_QueryTimeout']
UserName也变成了Zhanghao：
>>> u = ctx.Yonghus[0]
>>> dir(u)
['CodeRepresentation', 'DelAttrMethod', 'EmailAddress', 'EntityKey', 'Equals', 'Finalize', 'GetAttribute', 'GetHashCode', 'GetType', 'Hash', 'LastLogon', 'MemberwiseClone', 'Password', 'PythonToString', 'Reduce', 'ReferenceEquals', 'RelationshipManager', 'SetAttrMethod', 'SetChangeTracker', 'Tiezis', 'ToString', 'UserID', 'Zhanghao', '__class__', '__delattr__', '__doc__', '__entityHelper', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', '_emailAddress', '_lastLogon', '_password', '_userID', '_zhanghao', 'get_EmailAddress', 'get_EntityKey', 'get_LastLogon', 'get_Password', 'get_RelationshipManager', 'get_Tiezis', 'get_UserID', 'get_Zhanghao', 'set_EmailAddress', 'set_EntityKey', 'set_LastLogon', 'set_Password', 'set_UserID', 'set_Zhanghao']
>>> u.Zhanghao
'abc'
同样的，Post成了Tiezi：
>>> p = ctx.Tiezis[0]
>>> dir(p)
['CodeRepresentation', 'CreatedDate', 'DelAttrMethod', 'EntityKey', 'Equals', 'Finalize', 'GetAttribute', 'GetHashCode', 'GetType', 'Hash', 'MemberwiseClone', 'Message', 'ModifiedDate', 'PostID', 'PythonToString', 'Reduce', 'ReferenceEquals', 'RelationshipManager', 'SetAttrMethod', 'SetChangeTracker', 'Title', 'ToString', 'Yonghu', '__class__', '__delattr__', '__doc__', '__entityHelper', '__getattribute__', '__hash__', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', '_createdDate', '_message', '_modifiedDate', '_postID', '_title', 'get_CreatedDate', 'get_EntityKey', 'get_Message', 'get_ModifiedDate', 'get_PostID', 'get_RelationshipManager', 'get_Title','get_Yonghu', 'set_CreatedDate', 'set_EntityKey', 'set_Message', 'set_ModifiedDate', 'set_PostID', 'set_Title', 'set_Yonghu']
>>> p.Yonghu.Zhanghao
'abc'
3.如果结构不同的话，那么需要使用实体模型的中的CSDL,SSDL,和MSL来做映射，具体参考样例或文档
二。 除了结构性方面的定制，还能定制对象的行为么？
在Jasper的安装里，有一个VB.NET的Customization的例程，其中的App_Code中的BusinessLogic.vb：
Imports Microsoft.VisualBasic
'Project Jasper will create a Product class based on the Northwind schema
'At class creation time, Jasper will find this class and derive from it
'Jasper will find the SetUnitPrice function and call it from inside of
'the setter for the UnitPrice property on the Product class it creates
Public Class Product
Public Function SetUnitPrice(ByVal value As Decimal) As Decimal
If value < 0 Then
Throw New Exception("Can't set UnitPrice to a negative value")
Else
Return value
End If
End Function
End Class
其中的注释说，
“
Project会根据Northwind数据库的数据定义创建一个Product类
在创建类时，Jasper会发现这个类（指上面BusinessLogic.vb里定义的这个Product类），然后从这个类继承
Jasper会发现SetUnitPrice函数，然后在它创建的Product类的UnitPrice属性的setter里调用这个函数
”
如果你用Reflector看一下，你会发现DynamicContext.SaveChanges()->DynamicContext.SetupEntitiesForChanges()时看实体对象是否拥有OnPersist()方法，如果有的话，就会调用这个方法
让我们来在IronPython里试验一下
>>> import clr
>>> import System
>>> from System import *
创建一个类，继承自System.Object，内含2个方法HelloWorld和SetCreatedDate：
>>> class Post(System.Object):
... def HelloWorld(self):
... return 'hello world'
... def SetCreatedDate(self,dt):
... if (dt < DateTime.Now):
... raise Exception("CreatedDate must be in the future")
...
导入所需类
>>> clr.AddReference("Microsoft.Jasper.CTP")
>>> from Microsoft.Jasper import *
设置连接字符串
>>> connStr = "Provider='System.Data.SqlClient';Provider Connection String='Initial Catalog=Jasper;Data Source=.\SQLExpress;Integrated Security=True;';Generate Default EDM=True"
创建动态上下文，生成实体类
>>> ctx = DynamicContext.CreateDynamicContext(connStr)
取出昨天生成的贴子的一个对象
>>> p = ctx.Posts[0]
看一下其中的方法
>>> for m in p.GetType().GetMethods(): print m.Name
...
set_PostID
set_Title
set_Message
set_CreatedDate
set_ModifiedDate
SetChangeTracker
get_EntityKey
set_EntityKey
get_RelationshipManager
get_PostID
get_Title
get_Message
get_CreatedDate
get_ModifiedDate
get_User
set_User
GetType
ToString
Equals
GetHashCode
好像没有HelloWorld和SetCreatedDate啊，看一下类型
>>> p.GetType().FullName
'dboModel.Post'
其基类
>>> p.GetType().BaseType.FullName
'System.Object'
>>>
没有继承啊，生成一个Post对象，看一下其类型
>>> p2 = Post()
>>> p2.GetType().FullName
'IronPython.NewTypes.System.Object_1'
>>>
类名居然不是Post,而是IronPython.NewTypes.System.Object_1！ 看来Python里的类跟.NET里的类还是有区别的啊!
那就用C#写个类吧， dboModel.cs：
using System;
using System.Reflection;
namespace DomainModel
{
public class Post
{
//因为是静态的语言，无法获取还不存在的数据，在这里加一个成员变量保存数据为OnPersist()所用
DateTime _createdDate;
public DateTime SetCreatedDate(DateTime dt)
{
Console.WriteLine("in memory:{0}, passed in:{1}", _createdDate, dt);
//这里有关校验，传入的时间必须是现在或将来，否则出错
if (dt < DateTime.Now)
throw new Exception("CreatedDate must be in the future");
_createdDate = dt;
return dt;
}
public void Test()
{
Console.WriteLine("Test");
}
public void OnPersist()
{
//这是另一个校验，_createdDate不能是明天以后，应该在SetCreatedDate里做的，但。。。。
if (_createdDate >= DateTime.Now.AddDays(1))
throw new Exception("CreatedDate cannot go beyond tomorrow");
}
}
}
编译成dboModel.dll
csc /t:library dboModel.cs
>>> import clr
>>> import System
>>> from System import *
>>>
>>> clr.AddReference("Microsoft.Jasper.CTP")
>>> from Microsoft.Jasper import *
>>>
导入dboModel.dll里的类
>>> clr.AddReference("dboModel.dll")
>>> import DomainModel.Post
>>>
>>> connStr = "Provider='System.Data.SqlClient';Provider Connection String='Initial Catalog=Jasper;Data Source=.\SQLExpress;Integrated Security=True;';Generate Default EDM=True"
>>> ctx = DynamicContext.CreateDynamicContext(connStr)
取出昨天生成的贴子的一个对象
>>> p = ctx.Posts[0]
>>> p.GetType().FullName
'dboModel.Post'
基类
>>> p.GetType().BaseType.FullName
'DomainModel.Post'
这回对了
>>> for m in p.GetType().GetMethods() : print m.Name
...
set_PostID
set_Title
set_Message
set_CreatedDate
SetCreatedDate
set_ModifiedDate
SetChangeTracker
get_EntityKey
set_EntityKey
get_RelationshipManager
get_PostID
get_Title
get_Message
get_CreatedDate
get_ModifiedDate
get_User
set_User
Test
OnPersist
GetType
ToString
Equals
GetHashCode
>>> p = ctx.Posts[0]
>>> p.CreatedDate = DateTime.Now.AddDays(-1)
in memory:1/1/0001 12:00:00 AM, passed in:5/1/2007 4:29:28 PM
Traceback (most recent call last):
File , line 0, in <stdin>##27
File , line 0, in set_CreatedDate##31
File dynamicAssembly1, line unknown, in set_CreatedDate
File Microsoft.Jasper.CTP, line unknown, in CallMethodIfExists
Exception: CreatedDate must be in the future
>>>
看来SetCreatedDate真被调用了
>>> p.CreatedDate = DateTime.Now.AddDays(2)
in memory:1/1/0001 12:00:00 AM, passed in:5/4/2007 4:30:20 PM
试着保存
>>> ctx.SaveChanges()
Traceback (most recent call last):
File dboModel, line unknown, in OnPersist
File , line 0, in <stdin>##33
File , line 0, in SaveChanges##34
File Microsoft.Jasper.CTP, line unknown, in SaveChanges
File Microsoft.Jasper.CTP, line unknown, in SetupEntitiesForChanges
StandardError: Exception has been thrown by the target of an invocation.
出错了，没显示具体错误信息，奇怪
继承法大致如此，虽然还有些细节不是很对，但就到此为止吧
三。但，IronPython是门动态语言，我一定要用继承才行么？我不能动态添加方法么？
譬如在Python里，你可以这么做
>>> class A:
... def HelloWorld(self):
... self.af = "hello"
... def Print(self):
... print self.af
...
>>> A
<class __main__.A at 0x000000000000002C>
>>> a = A()
>>> a.HelloWorld()
>>> a.Print()
hello
定义一个新方法，
>>> def HelloWorld2(self):
... self.af = "hello 2"
...
使用setattr：
>>> setattr(A, HelloWorld2.__name__, HelloWorld2)
调用新的方法：
>>> a.HelloWorld2()
>>> a.Print()
hello 2
可以给.NET 类动态添加方法么？用上面那个C#写的Post类作为例子：
>>> from DomainModel import *
>>> def HelloWorld2(self):
... self.af = "hello 2"
...
>>> Post
<type 'Post'>
>>>
>>> setattr(Post,HelloWorld2.__name__,HelloWorld2)
Traceback (most recent call last):
File , line 0, in <stdin>##23
File , line 0, in SetAttr##24
AttributeError: 'Post' object has no attribute 'HelloWorld2'
好像不行！
看来我的IronPython的道行还比较浅，请哪位对IronPython有研究的指点一下，谢谢！
1.建立数据库
use master
go
create database Jasper
go
use Jasper
go
CREATE TABLE Users (
UserID int identity NOT NULL,
UserName nvarchar(40) NOT NULL,
Password nvarchar(20) NOT NULL,
EmailAddress nvarchar(40) NOT NULL,
LastLogon datetime,
PRIMARY KEY (UserID)
)
go
CREATE TABLE Posts (
PostID int identity NOT NULL,
Title nvarchar(100) NOT NULL,
Message ntext,
CreatedDate datetime,
ModifiedDate datetime,
UserID int NOT NULL,
PRIMARY KEY (PostID),
FOREIGN KEY (UserID) References Users(UserID)
)
go
2. 运行ipy命令行工具
C:\>ipy
IronPython 1.1 (1.1) on .NET 2.0.50727.1318
Copyright (c) Microsoft Corporation. All rights reserved.
3. 装载所需库
>>> import clr
>>> clr.AddReference("Microsoft.Jasper.CTP")
>>> from Microsoft.Jasper import *
4. 设置连接字符串，注意我们使用了默认的机制来通过实体框架动态生成对象
>>> connStr = "Provider='System.Data.SqlClient';Provider Connection String='Initial Catalog=Jasper;Data Source=.\SQLExpress;Integrated Security=True;';Generate Default EDM=True"
5. 生成动态上下文对象
>>> ctx = DynamicContext.CreateDynamicContext(connStr)
6. 看一下ctx对象的成员
>>> dir(ctx)
['AcceptAllChanges', 'AddObject', 'Attach', 'AttachTo', 'Connection', 'ContextSaved', 'ContextSaving', 'CreateDynamicContext', 'CreateKey', 'CreateQuery', 'DefaultContainerName', 'DeleteObject', 'Detach', 'Dispose', 'Equals', 'ExecuteDirectQuery', 'ExecuteFunction', 'ExecuteNativeMethod', 'Finalize', 'GetHashCode', 'GetObjectByKey', 'GetQuery', 'GetType', 'MakeDynamicType', 'MemberwiseClone', 'MetadataWorkspace', 'ObjectStateManager', 'Posts', 'QueryTimeout', 'Reduce', 'ReferenceEquals', 'Refresh', 'SaveChanges', 'ToString', 'TryGetObjectByKey', 'TryGetQuery', 'Users', '__class__', '__doc__', '__entityHelper', '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '_posts', '_users', 'add_ContextSaved', 'add_ContextSaving', 'remove_ContextSaved', 'remove_ContextSaving']
里面有Users和Posts
7. 目前数据库还没有任何数据
>>> ctx.Users.Count()
0
>>> ctx.Posts.Count()
0
8. 让我们来生成一个User对象
>>> u = ctx.Users.Create()
>>> u.UserName = "joel_cool"
>>> u.Password = "abc123"
>>> u.EmailAddress = "joe@cool.com"
>>> u.LastLogon = DateTime.Now
Traceback (most recent call last):
File , line 0, in <stdin>##42
NameError: name 'DateTime' not defined
>>> u.LastLogon = System.DateTime.Now
Traceback (most recent call last):
File , line 0, in <stdin>##43
NameError: name 'System' not defined
>>> from System import *
>>> u.LastLogon = DateTime.Now
>>> ctx.SaveChanges()
1
>>> ctx.Users.Count()
1
>>> u.UserID
1
忘了引进System命名空间
9. 生成几个贴子对象
>>> p = ctx.Posts.Create()
>>> p.User = u
>>> p.Title = "abc"
>>> p.Message = "Hello world"
>>> p.CreatedDate = p.ModifiedDate = DateTime.Now
>>>
>>> p2 = ctx.Posts.Create()
>>> p2.User = u
>>> p2.Title = "def"
>>> p2.Message = "Jasper is fun"
>>> p2.CreatedDate = p2.ModifiedDate = DateTime.Now
>>> ctx.SaveChanges()
4
>>> ctx.Posts.Count()
2
>>> p.PostID
1
>>> p2.PostID
2
>>> u.Posts.Count()
2
10. 查询一个贴子，然后做修改
>>> p3 = ctx.Posts.FindByKey(2)
>>> p3
<Post object at 0x000000000000002B>
>>> p2
<Post object at 0x000000000000002B>
>>>注意p2和p3指向同一个对象ID
>>> p3.Message += ", yes, really fun"
>>> p3.ModifiedDate = DateTime.Now
>>> ctx.SaveChanges()
1
>>> p2.Message
'Jasper is fun, yes, really fun'
>>> p2.CreatedDate
<System.DateTime object at 0x000000000000002C [5/1/2007 8:15:16 PM]>
>>> p2.ModifiedDate
<System.DateTime object at 0x000000000000002D [5/1/2007 8:17:18 PM]>
11. 删除其中一个贴子
>>> p4 = u.Posts.FindByKey(1)
>>> ctx.Posts.Delete(p4)
True
>>> ctx.SaveChanges()
2
>>> ctx.Posts.Count()
1
>>> u.Posts.Count()
2
#！！！好像有问题，用户对象还需要从自己的贴子集合里删除贴子，是特性还是缺陷？ 看样子这里需要一个用法模式
>>> p4.User
Traceback (most recent call last):
File , line 0, in <stdin>##106
File , line 0, in get_User##107
File dynamicAssembly1, line unknown, in get_User
File Microsoft.Jasper.CTP, line unknown, in GetRelatedReferenceValue
File System.Data.Entity.CTP, line unknown, in Load
SystemError: Unable to load the EntityReference because it is not attached to a
context.
#但这里p4指向的User已经出问题了，p3呢？
>>> p3.User
<User object at 0x000000000000002E>
>>> p3.User.UserName
'joel_cool'
12.把用户也删除吧
>>> ctx.Users.Delete(u)
True
>>> ctx.SaveChanges()
Traceback (most recent call last):
File , line 0, in <stdin>##116
File , line 0, in SaveChanges##49
File Microsoft.Jasper.CTP, line unknown, in SaveChanges
File System.Data.Entity.CTP, line unknown, in SaveChanges
File System.Data.Entity.CTP, line unknown, in SaveChanges
File System.Data.Entity.CTP, line unknown, in Update
File System.Data.Entity.CTP, line unknown, in Update
File System.Data.Entity.CTP, line unknown, in ValidateConstraints
SystemError: A relationship is being added or deleted from relationship set 'FK__Posts__UserID__7F60ED59'. Given cardinality constraints, a corresponding 'Posts' must also be added or deleted.
>>>
外键约束的关系，无法删除用户，把贴子也全删了！
>>> ctx.Posts.DeleteAll()
>>> ctx.SaveChanges()
3
>>> ctx.Users.Count()
0
>>> ctx.Posts.Count()
0
>>> u.Posts.Count()
2
