T4 (Text Template Transformation Toolkit)实现简单实体代码生成

     在很多场景下，我们都需要代码生成。你可以使用CodeSmith，不过它是商业软件。VisualStudio2008中自带也有代码生成功能。那就是T4 (Text Template Transformation Toolkit)模板。最近写了个简单Entity模板,直接看内容，连接Northwind database 生成所有Table的Entity：

<#@ template language="C#" hostspecific="true" #>
<#@ output extension="cs" #>
<#@ assembly name="Microsoft.SqlServer.ConnectionInfo" #>
<#@ assembly name="Microsoft.SqlServer.Smo" #>
<#@ assembly name="Microsoft.SqlServer.Management.Sdk.Sfc" #>
<#@ import namespace="Microsoft.SqlServer.Management.Smo" #>
<#
    // Config variables
    string serverName = "USER\\SQLEXPRESS2008";
    string dbName = "NORTHWND";
#>
using System;

/// Right click .tt file "Run Custom Tool" to update partial model.
/// Author Petter Liu  http://wintersun.cnblogs.com
namespace MyApp.CommonEntity
{
<#
    // Iterate over tables and generate procs
    Server server = new Server(new Microsoft.SqlServer.Management.Common.ServerConnection(serverName, "sa", "sa"));
    Database database = new Database(server, dbName);
    database.Refresh();

    foreach (Table table in database.Tables)
    {
 #>
     /// <summary>
     /// <#= table.Name #> Entity
     /// </summary>
     public partial class <#= table.Name #>
     {
 <#
        table.Refresh();
        string columnCsharptype="";
        string dbtypeStr="";
        foreach (Column column in table.Columns)
        {
          dbtypeStr=column.DataType.ToString();
          if (dbtypeStr=="nvarchar" || dbtypeStr=="nchar")
             columnCsharptype="string";
          else  if (column.DataType.ToString()=="ntext")
             columnCsharptype="string";
          else  if (column.DataType.ToString()=="varchar")
             columnCsharptype="string";
          else  if (column.DataType.ToString()=="char")
             columnCsharptype="string";
          else  if (column.DataType.ToString()=="text")
             columnCsharptype="string";
          else  if (column.DataType.ToString()=="smallint")
             columnCsharptype="Int16";
          else  if (column.DataType.ToString()=="datetime")
             columnCsharptype="DateTime";
          else  if (column.DataType.ToString()=="money")
             columnCsharptype="decimal";
          else  if (column.DataType.ToString()=="bit")
             columnCsharptype="bool";
          else  if (column.DataType.ToString()=="image")
             columnCsharptype="byte";
          else  if (column.DataType.ToString()=="real")
             columnCsharptype="single";
          else
             columnCsharptype=column.DataType.ToString();
#>
         /// <summary>
         /// Gets or sets the <#=column.Name#>
         /// </summary>
         /// <value>The <#=column.Name.ToLower()#></value>
         public <#=columnCsharptype #>  <#=column.Name#>  {get;set;}

 <#
        }
#>
    }

<#
    }
#>
}

你可以把它另存为扩展名为.tt的文件，我起名叫CommonEntity.tt。 然后在VisualStudio2008中选中它点击右键执行Run Custom Tool，就自动生成这样的代码：

using System;

/// Right click .tt file "Run Custom Tool" to update partial model.
/// Author Petter Liu  http://wintersun.cnblogs.com
namespace MyApp.CommonEntity
{
     /// <summary>
     /// Categories Entity
     /// </summary>
     public partial class Categories
     {
          /// <summary>
         /// Gets or sets the CategoryID
         /// </summary>
         /// <value>The categoryid</value>
         public int  CategoryID  {get;set;}

          /// <summary>
         /// Gets or sets the CategoryName
         /// </summary>
         /// <value>The categoryname</value>
         public string  CategoryName  {get;set;}

          /// <summary>
         /// Gets or sets the Description
         /// </summary>
         /// <value>The description</value>
         public string  Description  {get;set;}

          /// <summary>
         /// Gets or sets the Picture
         /// </summary>
         /// <value>The picture</value>
         public byte  Picture  {get;set;}

     }

这是最简约的Entity code了，实际你可扩展你所需要的模板。关于T4模板，网上有些资料可以参考：

T4 (Text Template Transformation Toolkit) Code Generation - Best Kept Visual Studio Secret

还有一些教程：