T4模板应用

Last updated on 9 months ago

T4模板应用（一）

之前在搭建系统框架的过程中用到的功能点，功效就是模板的功能。

个人是用T4模板批量生产到系统中的CRUD中，现在记录一下，不记录具体基础语法，只记录大概过程。

前提

ModelAuto.ttinclude

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<#@ 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"#>

<#+

class Manager
{
    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; }

    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;
            }
        }
    }
}#>

AllModelTemplate.tt

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<#@ template debug="true" hostspecific="true" language="C#" #>
<#@ output extension=".cs" #>
<#@ assembly name="System.Data" #>
<#@ assembly name="$(TargetDir)Oracle.ManagedDataAccess.dll" #>
<#@ assembly name="System.Xml" #>
<#@ import namespace="System" #>
<#@ import namespace="System.Xml" #>
<#@ import namespace="System.Data" #>
<#@ import namespace="Oracle.ManagedDataAccess" #>
<#@ import namespace="System.Collections.Generic"#>
<#@ include file="ModelAuto.ttinclude"#>
<# var manager2 = new Manager(Host, GenerationEnvironment, true) { OutputPath = Path.GetDirectoryName(Host.TemplateFile)}; #>
<# 
ModelManager manager = new ModelManager();
List<string> list=manager.GetTableList();
#>

<# 
    foreach (var item in list)
    {
		string tableName=item;
        DataTable table= manager.GetTableSchema(tableName);
 #>

 <# 
		manager2.StartBlock(tableName+".cs");
 #>
using System;
namespace Model
{
    /// <summary>
    /// 数据表实体类：<#= tableName #> 
    /// </summary>
    [Serializable()]
	public class <#= tableName #>
	{
<#
foreach(DataRow row in table.Rows)
{
#>
	   /// <summary>
	   /// <#=row["备注"]#>
	   /// </summary>     
	   public <#= manager.TransFromSqlType(row["数据类型"].ToString())#> <#=row["字段名"]#>{ get; set; }
<#}
#>
	}
}

<# manager2.EndBlock(); #>

<#
    }  
 #>	 
   
<# manager2.Process(true); #>

<#+
    public class ModelManager
    {
        /// <summary>
        /// 数据库连接字符串
        /// </summary> 
        private const string CONNECTION_STRING = "User ID=XLZF;Password=XLZF;Data Source=127.0.0.1/XE;";
        /// <summary>
        /// 用户信息表名
        /// </summary>
        private const string PERSONINFO_TABLE_NAME = "XLZF_USERS";
        /// <summary>
        /// 根据表名查询表结构信息
        /// </summary>
        private const string SELECT_SCHEMA_BY_TABLE_NAME = @"SELECT A.column_name    字段名,                                                                                     A.data_type      数据类型,
                                                                    A.data_length    长度,
                                                                    A.data_precision 整数位,
                                                                    A.Data_Scale     小数位,
                                                                    A.nullable       允许空值,
                                                                    A.Data_default   缺省值,
                                                                    B.comments       备注,
                                                                    A.TABLE_NAME     表名
                                                                    FROM user_tab_columns A,user_col_comments B  
                                                                    WHERE a.COLUMN_NAME = b.column_name
                                                                    AND A.Table_Name = B.Table_Name
                                                                    AND A.Table_Name = '{0}'";

        /// <summary>
        /// 获得数据连接
        /// </summary>
        /// <returns></returns>
        private Oracle.ManagedDataAccess.Client.OracleConnection GetConnection()
        {
            return new Oracle.ManagedDataAccess.Client.OracleConnection(CONNECTION_STRING);
        }

		
        /// <summary>
        /// 得到当前用户的所有表名
        /// </summary>
        /// <returns></returns>
        public List<string> GetTableList()
        {
            string sql = "SELECT * FROM USER_TABLES";
            DataTable dt = OracleHelper.ExecuteDataTable(sql);
            List<string> list = new List<string>();
            if (dt!=null&&dt.Rows.Count>0)
            {
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    list.Add(dt.Rows[i]["TABLE_NAME"].ToString());
                } 
            }
            return list;
         }

        /// <summary>
        /// 释放连接
        /// </summary>
        /// <param name="con"></param>
        private void ReleaseConnection(Oracle.ManagedDataAccess.Client.OracleConnection con)
        {
            if (con != null)
            {
                if (con.State == ConnectionState.Open)
                {
                    con.Close();
                }
            }
        }

        /// <summary>
        /// 获取表内字段及字段其他信息
        /// </summary>
        /// <param name="tableName"></param>
        public DataTable GetTableSchema(string tableName)
        {
            DataTable dt;

            using (Oracle.ManagedDataAccess.Client.OracleConnection con = GetConnection())
            {
                con.Open();

                Oracle.ManagedDataAccess.Client.OracleCommand cmd = con.CreateCommand();

                cmd.CommandText = string.Format(SELECT_SCHEMA_BY_TABLE_NAME,tableName);

                cmd.CommandType = CommandType.Text;

                Oracle.ManagedDataAccess.Client.OracleDataAdapter adapter = new Oracle.ManagedDataAccess.Client.OracleDataAdapter(cmd);

                DataSet ds = new DataSet(); 

                adapter.Fill(ds);

                dt = ds.Tables[0];
            }
            return dt;
        }

        /// <summary>
        /// SQL
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        public string TransFromSqlType(string type)
        {
            if (string.IsNullOrEmpty(type))
            {
                return string.Empty;
            }
			
            if (string.Equals(type, "number", StringComparison.OrdinalIgnoreCase))
            {
                return "int";
            }
			if (string.Equals(type, "date", StringComparison.OrdinalIgnoreCase))
            {
                return "DateTime";
            }
            else if (string.Equals(type, "nvarchar2", StringComparison.OrdinalIgnoreCase))
            {
                return "string";
            }
			
            return "string";
        } 

    }
#>

<#+ 
public class OracleHelper
    {

        private static string oracleConnectionStr = "User ID=XLZF;Password=XLZF;Data Source=127.0.0.1/XE;";


        public static DataTable ExecuteDataTable(string sql, params Oracle.ManagedDataAccess.Client.OracleParameter[] paramList)
        {
            using (Oracle.ManagedDataAccess.Client.OracleConnection conn = new Oracle.ManagedDataAccess.Client.OracleConnection(oracleConnectionStr))
            { 
                conn.Open();

                using (Oracle.ManagedDataAccess.Client.OracleCommand command = conn.CreateCommand())
                {
                    command.CommandText = sql;

                    command.Parameters.AddRange(paramList);

                    DataTable dt = new DataTable();

                    Oracle.ManagedDataAccess.Client.OracleDataAdapter adapter = new Oracle.ManagedDataAccess.Client.OracleDataAdapter(command);

                    adapter.Fill(dt);

                    return dt;
                }
            }
        }

        public static int ExecuteNonQuery(string sql, params Oracle.ManagedDataAccess.Client.OracleParameter[] paramList)
        {
            using (Oracle.ManagedDataAccess.Client.OracleConnection conn = new Oracle.ManagedDataAccess.Client.OracleConnection(oracleConnectionStr))
            {
                conn.Open();
                using (Oracle.ManagedDataAccess.Client.OracleCommand command = conn.CreateCommand())
                {
                    command.CommandText = sql;
                    command.Parameters.AddRange(paramList);

                    return command.ExecuteNonQuery();
                }
            }
        }

        public static object ExecuteScalar(string sql, params Oracle.ManagedDataAccess.Client.OracleParameter[] paramList)
        {
            using (Oracle.ManagedDataAccess.Client.OracleConnection conn = new Oracle.ManagedDataAccess.Client.OracleConnection(oracleConnectionStr))
            {
                conn.Open();
                using (Oracle.ManagedDataAccess.Client.OracleCommand command = conn.CreateCommand())
                {
                    command.CommandText = sql;
                    command.Parameters.AddRange(paramList);

                    return command.ExecuteScalar();
                }
            }
        }
    }
 #>

运行

右键运行T4模板

image-20211205210429402

image-20211205210452146

结果

image-20211205210516763

image-20211205210543104

T4模板应用（二）

这次是通过 MMSQL 然后运行 T4 模板，生产数据库中所有表对应的实体类

前提

ModelAuto.ttinclude 与前面的一致。

编码

ModelTemplate.tt

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<#@ template language="C#" debug="True" hostspecific="True" #>
<#@ output extension=".cs" #>
<#@ assembly name="System.Data" #>
<#@ assembly name="System.xml" #>
<#@ import namespace="System.Collections.Generic" #>
<#@ import namespace="System.Data.SqlClient" #>
<#@ import namespace="System.Data" #>
<#@ include file="ModelAuto.ttinclude"#>
<# var manager = new Manager(Host, GenerationEnvironment, true) { OutputPath = Path.GetDirectoryName(Host.TemplateFile)}; #>
<# 
	string connectionString = "Data Source=.;Initial Catalog=XLZF_TESTDB;User ID=sa;Password=MyMMSQL1433...;"; 
    SqlConnection conn = new SqlConnection(connectionString); 
    conn.Open(); 
    System.Data.DataTable schema = conn.GetSchema("TABLES"); 
    string selectQuery = "select * from @tableName"; 
    SqlCommand command = new SqlCommand(selectQuery,conn); 
    SqlDataAdapter ad = new SqlDataAdapter(command); 
    System.Data.DataSet ds = new DataSet();
 
    string propQuery = "SELECT 表名=sobj.name,字段名=scol.name,字段说明=sprop.[value] FROM syscolumns as scol inner join sys.sysobjects as sobj on scol.id=sobj.id and sobj.xtype='U' and sobj.name<>'dtproperties' left join sys.extended_properties as sprop on scol.id=sprop.major_id and scol.colid=sprop.minor_id where sobj.name='@tableName' and scol.name='@columnName'"; 
    SqlCommand command2 = new SqlCommand(propQuery,conn); 
    SqlDataAdapter ad2 = new SqlDataAdapter(command2); 
    System.Data.DataSet ds2 = new DataSet();
 #>

<# 
    foreach(System.Data.DataRow row in schema.Rows) 
    {  #>   

     <# 
		manager.StartBlock(row["TABLE_NAME"]+".cs");
	 #>
	//----------<#=row["TABLE_NAME"].ToString()#>开始----------
    
	using System;
	namespace MyProject.Entities 
	{
        /// <summary>
        /// 数据表实体类：<#= row["TABLE_NAME"].ToString() #> 
        /// </summary>
        [Serializable()]
        public class <#= row["TABLE_NAME"].ToString() #>
        {    
		    <#
            ds.Tables.Clear();
            command.CommandText = selectQuery.Replace("@tableName",row["TABLE_NAME"].ToString()); 
            ad.FillSchema(ds, SchemaType.Mapped, row["TABLE_NAME"].ToString());
            foreach (DataColumn dc in ds.Tables[0].Columns)
            { 
            #>
            <# 
             ds2.Tables.Clear();
             command2.CommandText = propQuery.Replace("@tableName",row["TABLE_NAME"].ToString()); 
             command2.CommandText = command2.CommandText.Replace("@columnName",dc.ColumnName); 
             ad2.Fill(ds2);
            #> 
			/// <summary>
			/// <#= dc.DataType.Name #>:<#=ds2.Tables[0].Rows[0].ItemArray[2]#>
			/// </summary>                       
			public <#= dc.DataType.Name #> <#= dc.ColumnName #> {get;set;}   
            <# }  #>   
        }    
     }

	//----------<#=row["TABLE_NAME"].ToString()#>结束----------

	<# manager.EndBlock(); #>

<# 
    } #> 

<#
    manager.Process(true);
#>

运行

常规右键-运行自定义工具

数据库

数据库表

运行结果

运行结果

image-20211205213257560

image-20211205213411337

T4模板应用（三）

本节主要描述给T4模板传参，应用T4模板生产指定的程序。

由于涉及到传参，先定义一个

参数实体

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[Serializable]
public class ParameterEntity
{
    /// <summary>
    /// 命名空间
    /// </summary>
    public string NameSpace { get; set; }

    /// <summary>
    /// 作者
    /// </summary>
    public string Auth { get; set; }

    /// <summary>
    /// 表名
    /// </summary>
    public string TableName { get; set; }

    /// <summary>
    /// 连接字符串
    /// </summary>
    public string ConnectionString { get; set; }
}

ModelAuto.ttinclude

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<#@ assembly name="System.Core"#>
<#@ assembly name="D:\2-技术实战\01-C#\04-Winform\DemoCode\packages\EnvDTE.8.0.2\lib\net10\EnvDTE.dll"#>
<#@ import namespace="System.Collections.Generic"#>
<#@ import namespace="System.IO"#>
<#@ import namespace="System.Text"#>
<#@ import namespace="Microsoft.VisualStudio.TextTemplating"#>

<#+

class Manager
{
    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; }

    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;
            }
        }
    }
}#>

启动方法

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public static void Mian_Two()
{
    ParameterEntity parameterEntity = new ParameterEntity();

    parameterEntity.Auth = "MR.XLZF";

    parameterEntity.ConnectionString = "User ID=XLZF;Password=XLZF;Data Source=127.0.0.1/XLZF;";

    parameterEntity.NameSpace = "T4ParameterSample";

    parameterEntity.TableName = "CONFIGTABLE";

    string T4File = "AllModelTemplate_1.tt";

    string templateFileName = Path.GetFullPath(T4File);

    CustomTextTemplatingEngineHost host = new CustomTextTemplatingEngineHost();

    Engine engine = new Engine();

    host.TemplateFileValue = templateFileName;

    host.Session = new TextTemplatingSession();

    host.Session.Add("parameter1", parameterEntity);

    string input = File.ReadAllText(templateFileName);

    string output = engine.ProcessTemplate(input, host);

    Console.WriteLine(output);

    foreach (CompilerError error in host.Errors)
    {
        Console.WriteLine(error.ToString());
    }

    Console.ReadLine();
}

CustomTextTemplatingEngineHost.cs

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.CodeDom.Compiler;
using System.IO;
using Microsoft.VisualStudio.TextTemplating;

namespace T4ParameterSample
{
    public class CustomTextTemplatingEngineHost : ITextTemplatingEngineHost, ITextTemplatingSessionHost
    {
        #region ITextTemplatingEngineHost
        //the path and file name of the text template that is being processed
        //---------------------------------------------------------------------
        internal string TemplateFileValue;
        public string TemplateFile
        {
            get { return TemplateFileValue; }
        }
        //This will be the extension of the generated text output file.
        //The host can provide a default by setting the value of the field here.
        //The engine can change this value based on the optional output directive
        //if the user specifies it in the text template.
        //---------------------------------------------------------------------
        private string fileExtensionValue = ".txt";
        public string FileExtension
        {
            get { return fileExtensionValue; }
        }
        //This will be the encoding of the generated text output file.
        //The host can provide a default by setting the value of the field here.
        //The engine can change this value based on the optional output directive
        //if the user specifies it in the text template.
        //---------------------------------------------------------------------
        private Encoding fileEncodingValue = Encoding.UTF8;
        public Encoding FileEncoding
        {
            get { return fileEncodingValue; }
        }
        //These are the errors that occur when the engine processes a template.
        //The engine passes the errors to the host when it is done processing,
        //and the host can decide how to display them. For example, the host 
        //can display the errors in the UI or write them to a file.
        //---------------------------------------------------------------------
        private CompilerErrorCollection errorsValue;
        public CompilerErrorCollection Errors
        {
            get { return errorsValue; }
        }
        //The host can provide standard assembly references.
        //The engine will use these references when compiling and
        //executing the generated transformation class.
        //--------------------------------------------------------------
        public IList<string> StandardAssemblyReferences
        {
            get
            {
                return new string[]
                {
                    //If this host searches standard paths and the GAC,
                    //we can specify the assembly name like this.
                    //---------------------------------------------------------
                    //"System"

                    //Because this host only resolves assemblies from the 
                    //fully qualified path and name of the assembly,
                    //this is a quick way to get the code to give us the
                    //fully qualified path and name of the System assembly.
                    //---------------------------------------------------------
                    typeof(System.Uri).Assembly.Location,
                    typeof(T4ParameterSample.Parameter).Assembly.Location
                };
            }
        }
        //The host can provide standard imports or using statements.
        //The engine will add these statements to the generated 
        //transformation class.
        //--------------------------------------------------------------
        public IList<string> StandardImports
        {
            get
            {
                return new string[]
                {
                    "System",
                    "T4ParameterSample"
                };
            }
        }
        //The engine calls this method based on the optional include directive
        //if the user has specified it in the text template.
        //This method can be called 0, 1, or more times.
        //---------------------------------------------------------------------
        //The included text is returned in the context parameter.
        //If the host searches the registry for the location of include files,
        //or if the host searches multiple locations by default, the host can
        //return the final path of the include file in the location parameter.
        //---------------------------------------------------------------------
        public bool LoadIncludeText(string requestFileName, out string content, out string location)
        {
            content = System.String.Empty;
            location = System.String.Empty;

            //If the argument is the fully qualified path of an existing file,
            //then we are done.
            //----------------------------------------------------------------
            if (File.Exists(requestFileName))
            {
                content = File.ReadAllText(requestFileName);
                return true;
            }
            //This can be customized to search specific paths for the file.
            //This can be customized to accept paths to search as command line
            //arguments.
            //----------------------------------------------------------------
            else
            {
                return false;
            }
        }
        //Called by the Engine to enquire about 
        //the processing options you require. 
        //If you recognize that option, return an 
        //appropriate value. 
        //Otherwise, pass back NULL.
        //--------------------------------------------------------------------
        public object GetHostOption(string optionName)
        {
            object returnObject;
            switch (optionName)
            {
                case "CacheAssemblies":
                    returnObject = true;
                    break;
                default:
                    returnObject = null;
                    break;
            }
            return returnObject;
        }
        //The engine calls this method to resolve assembly references used in
        //the generated transformation class project and for the optional 
        //assembly directive if the user has specified it in the text template.
        //This method can be called 0, 1, or more times.
        //---------------------------------------------------------------------
        public string ResolveAssemblyReference(string assemblyReference)
        {
            //If the argument is the fully qualified path of an existing file,
            //then we are done. (This does not do any work.)
            //----------------------------------------------------------------
            if (File.Exists(assemblyReference))
            {
                return assemblyReference;
            }
            //Maybe the assembly is in the same folder as the text template that 
            //called the directive.
            //----------------------------------------------------------------
            string candidate = Path.Combine(Path.GetDirectoryName(this.TemplateFile), assemblyReference);
            if (File.Exists(candidate))
            {
                return candidate;
            }
            //This can be customized to search specific paths for the file
            //or to search the GAC.
            //----------------------------------------------------------------
            //This can be customized to accept paths to search as command line
            //arguments.
            //----------------------------------------------------------------
            //If we cannot do better, return the original file name.
            return "";
        }
        //The engine calls this method based on the directives the user has 
        //specified in the text template.
        //This method can be called 0, 1, or more times.
        //---------------------------------------------------------------------
        public Type ResolveDirectiveProcessor(string processorName)
        {
            //This host will not resolve any specific processors.
            //Check the processor name, and if it is the name of a processor the 
            //host wants to support, return the type of the processor.
            //---------------------------------------------------------------------
            if (string.Compare(processorName, "XYZ", StringComparison.OrdinalIgnoreCase) == 0)
            {
                //return typeof();
            }
            //This can be customized to search specific paths for the file
            //or to search the GAC
            //If the directive processor cannot be found, throw an error.
            throw new Exception("Directive Processor not found");
        }
        //A directive processor can call this method if a file name does not 
        //have a path.
        //The host can attempt to provide path information by searching 
        //specific paths for the file and returning the file and path if found.
        //This method can be called 0, 1, or more times.
        //---------------------------------------------------------------------
        public string ResolvePath(string fileName)
        {
            if (fileName == null)
            {
                throw new ArgumentNullException("the file name cannot be null");
            }
            //If the argument is the fully qualified path of an existing file,
            //then we are done
            //----------------------------------------------------------------
            if (File.Exists(fileName))
            {
                return fileName;
            }
            //Maybe the file is in the same folder as the text template that 
            //called the directive.
            //----------------------------------------------------------------
            string candidate = Path.Combine(Path.GetDirectoryName(this.TemplateFile), fileName);
            if (File.Exists(candidate))
            {
                return candidate;
            }
            //Look more places.
            //----------------------------------------------------------------
            //More code can go here...
            //If we cannot do better, return the original file name.
            return fileName;
        }
        //If a call to a directive in a text template does not provide a value
        //for a required parameter, the directive processor can try to get it
        //from the host by calling this method.
        //This method can be called 0, 1, or more times.
        //---------------------------------------------------------------------
        public string ResolveParameterValue(string directiveId, string processorName, string parameterName)
        {
            if (directiveId == null)
            {
                throw new ArgumentNullException("the directiveId cannot be null");
            }
            if (processorName == null)
            {
                throw new ArgumentNullException("the processorName cannot be null");
            }
            if (parameterName == null)
            {
                throw new ArgumentNullException("the parameterName cannot be null");
            }
            //Code to provide "hard-coded" parameter values goes here.
            //This code depends on the directive processors this host will interact with.
            //If we cannot do better, return the empty string.
            return String.Empty;
        }
        //The engine calls this method to change the extension of the 
        //generated text output file based on the optional output directive 
        //if the user specifies it in the text template.
        //---------------------------------------------------------------------
        public void SetFileExtension(string extension)
        {
            //The parameter extension has a '.' in front of it already.
            //--------------------------------------------------------
            fileExtensionValue = extension;
        }
        //The engine calls this method to change the encoding of the 
        //generated text output file based on the optional output directive 
        //if the user specifies it in the text template.
        //----------------------------------------------------------------------
        public void SetOutputEncoding(System.Text.Encoding encoding, bool fromOutputDirective)
        {
            fileEncodingValue = encoding;
        }
        //The engine calls this method when it is done processing a text
        //template to pass any errors that occurred to the host.
        //The host can decide how to display them.
        //---------------------------------------------------------------------
        public void LogErrors(CompilerErrorCollection errors)
        {
            errorsValue = errors;
        }
        //This is the application domain that is used to compile and run
        //the generated transformation class to create the generated text output.
        //----------------------------------------------------------------------
        public AppDomain ProvideTemplatingAppDomain(string content)
        {
            //This host will provide a new application domain each time the 
            //engine processes a text template.
            //-------------------------------------------------------------

            //return AppDomain.CurrentDomain;
            return AppDomain.CreateDomain("Generation App Domain");
            //This could be changed to return the current appdomain, but new 
            //assemblies are loaded into this AppDomain on a regular basis.
            //If the AppDomain lasts too long, it will grow indefintely, 
            //which might be regarded as a leak.
            //This could be customized to cache the application domain for 
            //a certain number of text template generations (for example, 10).
            //This could be customized based on the contents of the text 
            //template, which are provided as a parameter for that purpose.
        }

        #endregion

        #region ITextTemplatingSessionHost
        public ITextTemplatingSession CreateSession()
        {
            return Session;
        }

        public ITextTemplatingSession Session
        {
            get;
            set;
        }
        #endregion
    }
}

AllModelTemplate_1.tt

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<#@ template debug="true" hostspecific="false" language="C#" #>
<#@ output extension=".txt" #>
<#@ assembly name="C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.8\System.Data.dll" #>
<#@ assembly name="C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.8\System.Data.OracleClient.dll" #>
<#@ assembly name="C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.8\System.Xml.dll" #>
<#@ assembly name="E:\Code\DemoCode\T4ParameterSample\bin\Debug\Oracle.ManagedDataAccess.dll" #>
<#@ import namespace="System" #>
<#@ import namespace="System.Xml" #>
<#@ import namespace="System.Data" #>
<#@ import namespace="Oracle.ManagedDataAccess" #>
<#@ import namespace="System.Collections.Generic"#>
<#@ include file="ModelAuto.ttinclude"#>
<#@ parameter name="parameter1" type="T4ParameterSample.ParameterEntity" #>
<# 
ModelManager manager = new ModelManager();
manager.CONNECTION_STRING = parameter1.ConnectionString;
List<string> list=manager.GetTableList(parameter1.TableName);
#>

<# 
    foreach (var item in list)
    {
		string tableName=item;
        DataTable table= manager.GetTableSchema(tableName);
 #>
using System;
using System.Data;
using System.Data.OracleClient;
namespace <#= parameter1.NameSpace #>
{
    /// <summary>
    /// 数据表实体类：<#= tableName #> 
	/// By: <#= parameter1.Auth #>
    /// </summary>
    [Serializable()]
	public class <#= tableName #>
	{
<#
foreach(DataRow row in table.Rows)
{
#>
	   /// <summary>
	   /// <#=row["备注"]#>
	   /// </summary>     
	   public <#= manager.TransFromSqlType(row["数据类型"].ToString())#> <#=row["字段名"]#>{ get; set; }
<#}
#>
	}
}

<#
    }  
 #>	 
   


<#+
    public class ModelManager
    {
        /// <summary>
        /// 数据库连接字符串
        /// </summary> 
        public string CONNECTION_STRING = "User ID=XLZF;Password=XLZF;Data Source=127.0.0.1/XE;";
        /// <summary>
        /// 用户信息表名
        /// </summary>
        public string PERSONINFO_TABLE_NAME = "XLZF_USERS";
        /// <summary>
        /// 根据表名查询表结构信息
        /// </summary>
        public string SELECT_SCHEMA_BY_TABLE_NAME = @"SELECT A.column_name    字段名,                                                                                     A.data_type      数据类型,
                                                                    A.data_length    长度,
                                                                    A.data_precision 整数位,
                                                                    A.Data_Scale     小数位,
                                                                    A.nullable       允许空值,
                                                                    A.Data_default   缺省值,
                                                                    B.comments       备注,
                                                                    A.TABLE_NAME     表名
                                                                    FROM user_tab_columns A,user_col_comments B  
                                                                    WHERE a.COLUMN_NAME = b.column_name
                                                                    AND A.Table_Name = B.Table_Name
                                                                    AND A.Table_Name = '{0}'";

        /// <summary>
        /// 获得数据连接
        /// </summary>
        /// <returns></returns>
        public Oracle.ManagedDataAccess.Client.OracleConnection GetConnection()
        {
            return new Oracle.ManagedDataAccess.Client.OracleConnection(CONNECTION_STRING);
        }

		
        /// <summary>
        /// 得到当前用户的所有表名
        /// </summary>
        /// <returns></returns>
        public List<string> GetTableList()
        {
            OracleHelper helper = new OracleHelper();
            
            string sql = "SELECT * FROM USER_TABLES";

            DataTable dt = helper.ExecuteDataTable(sql);

            List<string> list = new List<string>();

            if (dt!=null&&dt.Rows.Count>0)
            {
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    list.Add(dt.Rows[i]["TABLE_NAME"].ToString());
                } 
            }

            return list;
         }

		 /// <summary>
        /// 得到当前用户的所有表名
        /// </summary>
        /// <returns></returns>
        public List<string> GetTableList(string tableName)
        {
            string sql = "SELECT * FROM USER_TABLES WHERE TABLE_NAME = '"+tableName+"' ";

			OracleHelper helper = new OracleHelper();

			helper.oracleConnectionStr = CONNECTION_STRING;
			
            DataTable dt = helper.ExecuteDataTable(sql);

            List<string> list = new List<string>();

            if (dt!=null&&dt.Rows.Count>0)
            {
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    list.Add(dt.Rows[i]["TABLE_NAME"].ToString());
                } 
            }

            return list;
         }

        /// <summary>
        /// 释放连接
        /// </summary>
        /// <param name="con"></param>
        public void ReleaseConnection(Oracle.ManagedDataAccess.Client.OracleConnection con)
        {
            if (con != null)
            {
                if (con.State == ConnectionState.Open)
                {
                    con.Close();
                }
            }
        }

        /// <summary>
        /// 获取表内字段及字段其他信息
        /// </summary>
        /// <param name="tableName"></param>
        public DataTable GetTableSchema(string tableName)
        {
            DataTable dt;

            using (Oracle.ManagedDataAccess.Client.OracleConnection con = GetConnection())
            {
                con.Open();

                Oracle.ManagedDataAccess.Client.OracleCommand cmd = con.CreateCommand();

                cmd.CommandText = string.Format(SELECT_SCHEMA_BY_TABLE_NAME,tableName);

                cmd.CommandType = CommandType.Text;

                Oracle.ManagedDataAccess.Client.OracleDataAdapter adapter = new Oracle.ManagedDataAccess.Client.OracleDataAdapter(cmd);

                DataSet ds = new DataSet(); 

                adapter.Fill(ds);

                dt = ds.Tables[0];
            }
            return dt;
        }

        /// <summary>
        /// SQL
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        public string TransFromSqlType(string type)
        {
            if (string.IsNullOrEmpty(type))
            {
                return string.Empty;
            }
			
            if (string.Equals(type, "number", StringComparison.OrdinalIgnoreCase))
            {
                return "int";
            }
			if (string.Equals(type, "date", StringComparison.OrdinalIgnoreCase))
            {
                return "DateTime";
            }
            else if (string.Equals(type, "nvarchar2", StringComparison.OrdinalIgnoreCase))
            {
                return "string";
            }
			
            return "string";
        } 

    }
#>

<#+ 
public class OracleHelper
    {

        public string oracleConnectionStr = "User ID=XLZF;Password=XLZF;Data Source=127.0.0.1/XLZF;";


        public DataTable ExecuteDataTable(string sql, params Oracle.ManagedDataAccess.Client.OracleParameter[] paramList)
        {
            using (Oracle.ManagedDataAccess.Client.OracleConnection conn = new Oracle.ManagedDataAccess.Client.OracleConnection(oracleConnectionStr))
            { 
                conn.Open();

                using (Oracle.ManagedDataAccess.Client.OracleCommand command = conn.CreateCommand())
                {
                    command.CommandText = sql;

                    command.Parameters.AddRange(paramList);

                    DataTable dt = new DataTable();

                    Oracle.ManagedDataAccess.Client.OracleDataAdapter adapter = new Oracle.ManagedDataAccess.Client.OracleDataAdapter(command);

                    adapter.Fill(dt);

                    return dt;
                }
            }
        }

        public int ExecuteNonQuery(string sql, params Oracle.ManagedDataAccess.Client.OracleParameter[] paramList)
        {
            using (Oracle.ManagedDataAccess.Client.OracleConnection conn = new Oracle.ManagedDataAccess.Client.OracleConnection(oracleConnectionStr))
            {
                conn.Open();
                using (Oracle.ManagedDataAccess.Client.OracleCommand command = conn.CreateCommand())
                {
                    command.CommandText = sql;
                    command.Parameters.AddRange(paramList);

                    return command.ExecuteNonQuery();
                }
            }
        }

        public object ExecuteScalar(string sql, params Oracle.ManagedDataAccess.Client.OracleParameter[] paramList)
        {
            using (Oracle.ManagedDataAccess.Client.OracleConnection conn = new Oracle.ManagedDataAccess.Client.OracleConnection(oracleConnectionStr))
            {
                conn.Open();
                using (Oracle.ManagedDataAccess.Client.OracleCommand command = conn.CreateCommand())
                {
                    command.CommandText = sql;
                    command.Parameters.AddRange(paramList);

                    return command.ExecuteScalar();
                }
            }
        }
    }
 #>

结果

image-20211205223643141

结合传参功能的实现，在结合多种数据库，可以实现多种批量生产代码的功能，后续补充个人工具中的应用。

C#
#T4
T4模板应用
http://example.com/2021/11/26/T4模板应用/
Author
Harris
Posted on
November 26, 2021
Licensed under