基於數據庫的vs2019的T4模版代碼生成器（一）基於sqlserver數據庫

總體介紹

參考文檔：

https://www.cnblogs.com/laozhang-is-phi/p/9757999.html

只想用 ADO.NET 搭建多層框架，動軟代碼生成器是一個不錯的選擇。

T4 (Text Template Transformation Toolkit) 是微軟官方在 VisualStudio 2008+ 中開始使用的代碼生成引擎。在 Visual Studio 中，“T4 文本模板”是由一些文本塊和控制邏輯組成的混合模板，它可以生成文本文件。 在 Visual C# 或 Visual Basic 中，控制邏輯編寫為程序代碼的片段。生成的文件可以是任何類型的文本，例如網頁、資源文件或任何語言的程序源代碼。現在的VS中只要與代碼生成相關的場景基本上都能找T4的身影，比如MVC的視圖模板，Entity Framwork的DataContext模板等等。

 這里就不具體講解 T4 語法了，大家可以自行學習，其實很簡單，主要還是 C# 代碼，下邊你看過之后就能懂了，咱們首先先實現之前留下的一個伏筆 —— 將我們的數據庫表利用T4 模板生成實體類，也就是 DbFirst。

1、首先在我們的項目中，新建一個類庫 Xwy.Core.FrameWorkT4 

2、在該類庫下，新建文件夾 Xwy.Core.FrameWorkT4.Entity，用於單獨存放我們的模板以及生成的實體類文件

3、 ModelAuto.ttinclude 文本文件代碼

//引入命名空間
<#@ 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"#>

<#+
//定義管理者 manager 實體類
class Manager
{
    //定義一個 block 塊，主要是應用在批量生產中
    public struct Block {
        public String Name;
        public int Start, Length;
    }

    public List<Block> blocks = new List<Block>();
    public Block currentBlock;
    public Block footerBlock = new Block();
    public Block headerBlock = new Block();
    public ITextTemplatingEngineHost host;
    public ManagementStrategy strategy;
    public StringBuilder template;
    public String OutputPath { get; set; }
    //構造函數，包含 host主機，模板，輸出路徑，創建管理策略
    public Manager(ITextTemplatingEngineHost host, StringBuilder template, bool commonHeader) {
        this.host = host;
        this.template = template;
        OutputPath = String.Empty;
        strategy = ManagementStrategy.Create(host);
    }
    //開辟一個 block 塊
    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);
    }
    //定義進程，用來將所有的 blocks 塊執行出來
    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) {//遍歷
            //輸出文件
            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);
            }
        }
    }
}
//定義管理策略類
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);
    }
    //創建文件
    internal override void CreateFile(String fileName, String content) {
        base.CreateFile(fileName, content);
        ((EventHandler)delegate { templateProjectItem.ProjectItems.AddFromFile(fileName); }).BeginInvoke(null, null, null, null);
    }
    //刪除文件
    internal override void DeleteFile(String fileName) {
        ((EventHandler)delegate { FindAndDeleteFile(fileName); }).BeginInvoke(null, null, null, null);
    }
    //根據文件名刪除文件
    private void FindAndDeleteFile(String fileName) {
        foreach(EnvDTE.ProjectItem projectItem in templateProjectItem.ProjectItems) {
            if (projectItem.get_FileNames(0) == fileName) {
                projectItem.Delete();
                return;
            }
        }
    }
}#>

5 DbHelper.ttinclude文本文件

//引入命名空間
<#@ 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"#>

<#+
//定義管理者 manager 實體類
class Manager
{
    //定義一個 block 塊，主要是應用在批量生產中
    public struct Block {
        public String Name;
        public int Start, Length;
    }

    public List<Block> blocks = new List<Block>();
    public Block currentBlock;
    public Block footerBlock = new Block();
    public Block headerBlock = new Block();
    public ITextTemplatingEngineHost host;
    public ManagementStrategy strategy;
    public StringBuilder template;
    public String OutputPath { get; set; }
    //構造函數，包含 host主機，模板，輸出路徑，創建管理策略
    public Manager(ITextTemplatingEngineHost host, StringBuilder template, bool commonHeader) {
        this.host = host;
        this.template = template;
        OutputPath = String.Empty;
        strategy = ManagementStrategy.Create(host);
    }
    //開辟一個 block 塊
    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);
    }
    //定義進程，用來將所有的 blocks 塊執行出來
    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) {//遍歷
            //輸出文件
            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);
            }
        }
    }
}
//定義管理策略類
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);
    }
    //創建文件
    internal override void CreateFile(String fileName, String content) {
        base.CreateFile(fileName, content);
        ((EventHandler)delegate { templateProjectItem.ProjectItems.AddFromFile(fileName); }).BeginInvoke(null, null, null, null);
    }
    //刪除文件
    internal override void DeleteFile(String fileName) {
        ((EventHandler)delegate { FindAndDeleteFile(fileName); }).BeginInvoke(null, null, null, null);
    }
    //根據文件名刪除文件
    private void FindAndDeleteFile(String fileName) {
        foreach(EnvDTE.ProjectItem projectItem in templateProjectItem.ProjectItems) {
            if (projectItem.get_FileNames(0) == fileName) {
                projectItem.Delete();
                return;
            }
        }
    }
}#>

6 模板文件Entity.tt

//如果要獲取主機信息，記得把 hostspecific 設置成true
<#@ template debug="false" hostspecific="True" language="C#" #>
<#@ output extension=".cs" #>

//導入命名空間組件
<#@ assembly name="System.Data" #>
<#@ assembly name="System.xml" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.Data.SqlClient" #>
<#@ import namespace="System.Data" #>
<#@ assembly name="System.Core.dll" #>
<#@ assembly name="System.Data.DataSetExtensions.dll" #>
<#@ import namespace="System" #>
<#@ import namespace="System.Xml" #>
<#@ import namespace="System.Linq" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.IO" #>

//引入我們的公共模板文件
<#@ include file="$(ProjectDir)DbHelper.ttinclude"  #>
<#@ include file="$(ProjectDir)ModelAuto.ttinclude"    #>

//定義我們的輸出文件夾
<# 
    var OutputPath1 = Path.GetDirectoryName(Host.TemplateFile)+"\\work";
    if (!Directory.Exists(OutputPath1))
    {
        Directory.CreateDirectory(OutputPath1);
    }
     var manager = new Manager(Host, GenerationEnvironment, true) { OutputPath = OutputPath1 }; 
#>


//--------------------------------------------------------------------
//     此代碼由T4模板自動生成
//    老張的哲學 生成時間 <#=DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")#> 
//     注意更新后會改變相應代碼。
//--------------------------------------------------------------------
<# 
    var tableName=config.TableName;//獲取config配置中的表名，為單一生產使用
 #>
<# 
if(tableName!=""){//如果表名有值，表示是生成單一文件
    #>  
//引用命名空間
using System;
namespace Blog.Core.FrameWork.Entity
{    
    /// <summary>
    /// <#=tableName#>
    /// </summary>    
    public class <#=tableName#>//可以在這里加上基類等
    {
    //將全部字段遍歷出來
<# foreach(DbColumn column in DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, config.TableName)){#>
      public <#= column.CSharpType#><# if(column.CommonType.IsValueType && column.IsNullable){#>?<#}#> <#=column.ColumnName#> { get; set; }
<#}#> 
    }
}
//如果為空，表示要將整個數據庫都生成出來
<# 
    } else{ 

    #>
    //連接數據庫，打開 connect 連接
<# 
    SqlConnection conn = new SqlConnection(config.ConnectionString); 
    conn.Open(); 
    System.Data.DataTable schema = conn.GetSchema("TABLES"); 
 #>
 //遍歷全部數據庫表
<# 
    foreach(System.Data.DataRow row in schema.Rows) 
    {  #>   

    //開始啟動block塊，參數是實體類文件名
    <# 
        manager.StartBlock(row["TABLE_NAME"]+".cs");
     #>
using System;
namespace Blog.Core.FrameWork.Entity
{    
    /// <summary>
    /// <#=tableName#>
    /// </summary>    
    public class <#=row["TABLE_NAME"].ToString()#>//可以在這里加上基類等
    {
    //將該表下的字段都遍歷出來，可以自定義獲取數據描述等信息
<# foreach(DbColumn column in DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, row["TABLE_NAME"].ToString() )){ #>

      public <#= column.CSharpType#><# if(column.CommonType.IsValueType && column.IsNullable){#>?<#}#> <#=column.ColumnName #> { get; set; }
<#}#> 

    }
}
    <# 
        manager.EndBlock(); 
        } 
        manager.Process(true);
    }
    #>