T4 输出多文件

最近在做一个小的网站项目，使用subsonic 做ORMapping的工具, 发现subsonic3已经在使用T4做代码生成工具了，相对于subsonic2开发效率上有了不小的提升，遗憾的是使用subsonic自带的T4模板不能为数据表生成各自的类文件，后来发现Damieng写了一片T4多输出的文章，http://damieng.com/blog/2009/01/22/multiple-outputs-from-t4-made-easy 介绍了如何让T4模板多输出，试了一下，可用。 步骤如下
1.新建写字板文件，贴进代码：

<#@ assembly name="System.Core"#>

<#@ assembly name="EnvDTE"#>

<#@ import namespace="System.Collections.Generic"#>

<#@ import namespace="System.IO"#>

<#@ import namespace="System.Text"#>

<#@ import namespace="Microsoft.VisualStudio.TextTemplating"#>

<#+

// T4 Template Block manager for handling multiple file outputs more easily.
// Copyright (c) Microsoft Corporation.  All rights reserved.
// This source code is made available under the terms of the Microsoft Public License (MS-PL)

// Manager class records the various blocks so it can split them up
class Manager
{
    private struct Block {
        public String Name;
        public int Start, Length;
    }

    private List<Block> blocks = new List<Block>();
    private Block currentBlock;
    private Block footerBlock = new Block();
    private Block headerBlock = new Block();
    private ITextTemplatingEngineHost host;
    private ManagementStrategy strategy;
    private StringBuilder template;
    public String OutputPath { get; set; }

    public Manager(ITextTemplatingEngineHost host, StringBuilder template, bool commonHeader) {
        this.host = host;
        this.template = template;
        OutputPath = String.Empty;
        strategy = ManagementStrategy.Create(host);
    }

    public void StartBlock(String name) {
        currentBlock = new Block { Name = name, Start = template.Length };
    }

    public void StartFooter() {
        footerBlock.Start = template.Length;
    }

    public void EndFooter() {
        footerBlock.Length = template.Length - footerBlock.Start;
    }

    public void StartHeader() {
        headerBlock.Start = template.Length;
    }

    public void EndHeader() {
        headerBlock.Length = template.Length - headerBlock.Start;
    }    

    public void EndBlock() {
        currentBlock.Length = template.Length - currentBlock.Start;
        blocks.Add(currentBlock);
    }

    public void Process(bool split) {
        String header = template.ToString(headerBlock.Start, headerBlock.Length);
        String footer = template.ToString(footerBlock.Start, footerBlock.Length);
        blocks.Reverse();
        foreach(Block block in blocks) {
            String fileName = Path.Combine(OutputPath, block.Name);
            if (split) {
                String content = header + template.ToString(block.Start, block.Length) + footer;
                strategy.CreateFile(fileName, content);
                template.Remove(block.Start, block.Length);
            } else {
                strategy.DeleteFile(fileName);
            }
        }
    }
}

class ManagementStrategy
{
    internal static ManagementStrategy Create(ITextTemplatingEngineHost host) {
        return (host is IServiceProvider) ? new VSManagementStrategy(host) : new ManagementStrategy(host);
    }

    internal ManagementStrategy(ITextTemplatingEngineHost host) { }

    internal virtual void CreateFile(String fileName, String content) {
        File.WriteAllText(fileName, content);
    }

    internal virtual void DeleteFile(String fileName) {
        if (File.Exists(fileName))
            File.Delete(fileName);
    }
}

class VSManagementStrategy : ManagementStrategy
{
    private EnvDTE.ProjectItem templateProjectItem;

    internal VSManagementStrategy(ITextTemplatingEngineHost host) : base(host) {
        IServiceProvider hostServiceProvider = (IServiceProvider)host;
        if (hostServiceProvider == null)
            throw new ArgumentNullException("Could not obtain hostServiceProvider");

        EnvDTE.DTE dte = (EnvDTE.DTE)hostServiceProvider.GetService(typeof(EnvDTE.DTE));
        if (dte == null)
            throw new ArgumentNullException("Could not obtain DTE from host");

        templateProjectItem = dte.Solution.FindProjectItem(host.TemplateFile);
    }

    internal override void CreateFile(String fileName, String content) {
        base.CreateFile(fileName, content);
        ((EventHandler)delegate { templateProjectItem.ProjectItems.AddFromFile(fileName); }).BeginInvoke(null, null, null, null);
    }

    internal override void DeleteFile(String fileName) {
        ((EventHandler)delegate { FindAndDeleteFile(fileName); }).BeginInvoke(null, null, null, null);
    }

    private void FindAndDeleteFile(String fileName) {
        foreach(EnvDTE.ProjectItem projectItem in templateProjectItem.ProjectItems) {
            if (projectItem.get_FileNames(0) == fileName) {
                projectItem.Delete();
                return;
            }
        }
    }
}#>

 

保存文本文件，文件改名为manager.ttinclude

2. 修改ActiveRecord.tt

　　1). 在ActiveRecord.tt 中引用 manager.ttinclude

　　　　<#@ include file="Manager.ttinclude"#>

　　2). 紧接着定义manager变量， outPutPath指定了生成文件保存的路径

　　　　<# var manager = new Manager(Host, GenerationEnvironment, true) { OutputPath = Path.GetDirectoryName(Host.TemplateFile) }; #>

　　3). Subsonic3采用一个循环生成所有表的ActiveRecord类，所以在循环体中插入代码块开始标识，"AR_"+tbl.ClassName+".cs" 指定了生成的类文件名为以 'AR_'开始的cs文件

　　      <# manager.StartBlock("AR_"+tbl.ClassName+".cs"); #> 

　　4). 在循环结束处插入块结束标识

　　　　<# manager.EndBlock(); #>

5). 循环体中的Activerecord类使用共同的命名空间引用，因此对命名空间的引用及目标文件的命名空间部分都放在startHead和endHead标识中间
　　<# manager.StartHeader(); #>
　　using System;

　　using System.Collections.Generic;

　　using System.Linq;

　　...

　　...
　　namespace <#=Namespace #>

　　{

　　<# manager.EndHeader();#>

6). startFooter/endFooter标识之间只有一个}
　　<# manager.StartFooter();#>

　　}

　　<# manager.EndFooter(); #>

7). 模板结尾处写上处理标识，true分离文件，false 不分开文件

<# manager.Process(true); #>