T4模板生成自定义的实体类

1、开发工具

　　VS2017、Oracle、PL/SQL、T4Toolbox 

　　T4模板编辑工具 T4 Editor

2、数据库查询语句

　　2.1、oracle

--查询当前用户的所有表
SELECT TABLE_NAME FROM USER_TABLES;
--根据表名查询表结构数据
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 = 'test'
View Code

　　2.2、mysql

--查询数据库表
    string connectionString = "Data Source=.;Initial Catalog=NFineBase;User ID=sa;Password=hjf19870810;"; 
    SqlConnection conn = new SqlConnection(connectionString); 
    conn.Open(); 
    System.Data.DataTable schema = conn.GetSchema("TABLES"); 
--通过数据库表查询表结构
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'
View Code

　　2.3、sqlserver

--SQL 查询所有表名
SELECT NAME FROM SYSOBJECTS WHERE TYPE='U'
SELECT * FROM INFORMATION_SCHEMA.TABLES
--查询表的所有字段名
SELECT NAME FROM SYSCOLUMNS WHERE ID=OBJECT_ID(' 表名' )
View Code

3、生成类文件公用类 ModelAuto.ttinclude

<#@ 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 (!Directory.Exists(OutputPath))
            {
                Directory.CreateDirectory(OutputPath);
            }
            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;
            }
        }
    }
}#>
View Code

4、T4模板文件

<#@ template debug="true" hostspecific="true" language="C#" #>
<#@ output extension=".cs" #>
<#@ assembly name="System.Data" #>
<#@ assembly name="System.Xml" #>
<#@ assembly name="System.Linq" #>
<#@ assembly name="System.IO" #>
<#@ assembly name="$(ProjectDir)LibOracle.ManagedDataAccess.dll" #>
<#@ import namespace="System" #>
<#@ import namespace="System.Xml" #>
<#@ import namespace="System.Data" #>
<#@ import namespace="System.IO" #>
<#@ import namespace="System.Collections.Generic"#>
<#@ import namespace="System.Linq"#>
<#@ import namespace="Oracle.ManagedDataAccess.Client" #>
<#@ include file="ModelAuto.ttinclude"#>

<# var manager2 = new Manager(Host, GenerationEnvironment, true) { OutputPath = Path.GetDirectoryName(Host.TemplateFile)+"\DefaultModel"}; #>
<# 
ModelManager manager = new ModelManager();
List<string> list=manager.GetTableList();
#>

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

 <# 
        string tempTableName=manager.FirstCharToUpper(tableName);
        manager2.StartBlock(tempTableName+"Entity.cs");
 #>
/*********************************************************
* Copyright (c) 2019
* All rights reserved.
* 
* 文件名称：<#=tempTableName #>.cs
* 摘    要：业务实体<#=tableName#>的对象
*
* 当前版本：1.0.0
*
* 作    者：test
* 完成日期：<#=System.DateTime.Now.ToString("yyyy年MM月dd日") #>
*
*********************************************************/
using System;

namespace Common.Entity
{
    /// <summary>
    /// 业务实体<#= tableName #>的对象
    /// </summary>
    [Serializable]
    public class <#= tempTableName  #>Entity: BaseEntity, ITableInfo
    {
        #region Parameter List
<#
foreach(DataRow row in table.Rows)
{
#>
        private <#= manager.TransFromSqlType(row["数据类型"].ToString(),row["整数位"].ToString(),row["小数位"].ToString())#> <#= row["字段名"].ToString().ToLower()#> = <#= manager.MapValue(row["数据类型"].ToString(),row["整数位"].ToString(),row["小数位"].ToString()) #>;    //<#= row["备注"]#>

<#}
#>
        private string tableName = "<#= tableName #>";
        private string tableSchema = "";
        #endregion

        #region Property List
<#
foreach(DataRow row in table.Rows)
{
#>
        /// <summary>
        /// <#=row["备注"]#>
        /// </summary>   
        public <#= manager.TransFromSqlType(row["数据类型"].ToString(),row["整数位"].ToString(),row["小数位"].ToString())#> <#= manager.FirstCharToUpper(row["字段名"].ToString())#>
        {
            get
            {
                return <#= row["字段名"].ToString().ToLower() #>;
            }
            set
            {
                <#= row["字段名"].ToString().ToLower() #> = value;
            }
        }
       
<#}
#>
        #endregion

        #region ITableInfo Members
        /// <summary>
        /// Database Table Name
        /// </summary>
        public string TableName
        {
            get
            {
                return tableName;
            }
            set
            {
                tableName = value;
            }
        }

        /// <summary>
        /// Database Table Schema
        /// </summary>
        public string TableSchema
        {
            get
            {
                return tableSchema;
            }
            set
            {
                tableSchema = value;
            }
        }
        #endregion

    }
}

<# manager2.EndBlock(); #>

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

<#+
    public class ModelManager
    {
        /// <summary>
        /// 数据库连接字符串
        /// </summary>
       private const string CONNECTION_STRING = "DATA SOURCE=testPRO;USER ID=APP;PASSWORD=APP;";
        /// <summary>
        /// 用户信息表名
        /// </summary>
        private const string PERSONINFO_TABLE_NAME = "USERINFO";
        /// <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 OracleConnection GetConnection()
        {
            return new 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(OracleConnection con)
        {
            if (con != null)
            {
                if (con.State == ConnectionState.Open)
                {
                    con.Close();
                }
            }
        }

        public DataTable GetTableSchema(string tableName)
        {
            DataTable dt;
            using (OracleConnection con = GetConnection())
            {
                con.Open();
                OracleCommand cmd = con.CreateCommand();
                cmd.CommandText = string.Format(SELECT_SCHEMA_BY_TABLE_NAME,tableName);
                cmd.CommandType = CommandType.Text;
                OracleDataAdapter adapter = new OracleDataAdapter(cmd);
                DataSet ds = new DataSet(); 
                adapter.Fill(ds);
                dt = ds.Tables[0];
            }

            return dt;
        }

        public string FirstCharToUpper(string input)
        {
            if (String.IsNullOrEmpty(input))
                throw new ArgumentException("ARGH!");
            return input.First().ToString().ToUpper() + input.Substring(1).ToLower();
        }

        public string MapValue(string type, string number, string small)
        {
            string dataType = TransFromSqlType(type, number, small);
            if (string.Equals(dataType, "string", StringComparison.OrdinalIgnoreCase))
            {
                return "null";
            }
            else
            {
                return dataType + ".MinValue";
            }
        }

        /// <summary>
        /// SQL[不完善,需要的自己改造]
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        public string TransFromSqlType(string type, string number, string small)
        {
            if (string.IsNullOrEmpty(type))
            {
                return string.Empty;
            }
            if (string.Equals(type, "number", StringComparison.OrdinalIgnoreCase))
            {
                if (!string.IsNullOrEmpty(number))
                {
                    if (!string.IsNullOrEmpty(small) && int.Parse(small) > 0)
                    {
                        return "decimal";
                    }
                    if (int.Parse(number) >= 10 && (string.IsNullOrEmpty(small) || (!string.IsNullOrEmpty(small)&&int.Parse(small)==0)))
                    {
                        return "Int64";
                    }
                    else if (int.Parse(number) < 10 && (string.IsNullOrEmpty(small) || (!string.IsNullOrEmpty(small) && int.Parse(small) == 0)))
                    {
                        return "Int32";
                    }
                   
                }
                else
                {
                    return "Int32";
                }
            }
            if (string.Equals(type, "date", StringComparison.OrdinalIgnoreCase))
            {
                return "DateTime";
            }
            else if (string.Equals(type, "nvarchar2", StringComparison.OrdinalIgnoreCase) || string.Equals(type, "char", StringComparison.OrdinalIgnoreCase))
            {
                return "string";
            }
            return "string";
        }

    }
#>

<#+ 
public class OracleHelper
    {

        private static string oracleConnectionStr = "DATA SOURCE=testPRO;USER ID=APP;PASSWORD=APP;";
        public static DataTable ExecuteDataTable(string sql, params OracleParameter[] paramList)
        {
            using (OracleConnection conn = new OracleConnection(oracleConnectionStr))
            {
                conn.Open();
                using (OracleCommand command = conn.CreateCommand())
                {
                    command.CommandText = sql;
                    command.Parameters.AddRange(paramList);
                    DataTable dt = new DataTable();
                    OracleDataAdapter adapter = new OracleDataAdapter(command);
                    adapter.Fill(dt);
                    return dt;
                }
            }
        }

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

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

 #>
View Code

 生成文件如下图

5、T4模板语法

　　主要分为 1指令 2文本块 3指令块

  <# 标准控制块 #> 可以包含语句。
  <#= 表达式控制块 #> 可以包含表达式。
  <#+ 类功能控制块 #> 可以包含方法、字段和属性，就像一个类的内部

　　5.1 指令

　　主要包括template, output, assembly, import, include等类型

　　$(SolutionDir):当前项目所在解决方案目录
　　$(ProjectDir):当前项目所在目录
　　$(TargetPath):当前项目编译输出文件绝对路径
　　$(TargetDir):当前项目编译输出目录，即web项目的Bin目录，控制台、类库项目bin目录下的debug或release目录(取决于当前的编译模式)

　　5.2 文本块

　　文本块直接向输出文件插入文本。 文本块没有特殊格式，就像我们刚才初体验中写的类一样。

　　5.3 指令块

　　标准控制块：

<#
    for(int i = 0; i < 4; i++)
    {
#>
Hello World!
<#
    } 
#>
View Code

　　表达式控制块：

<#
    XmlDocument xDoc = new XmlDocument();
    xDoc.Load(@"E:CSharpOverview.xml");
    XmlAttributeCollection attributes = xDoc.Attributes;
    if (attributes != null)
    {
       foreach (XmlAttribute attr in attributes)
       {
#><#= attr.Name #><#
       }
    }
#>
View Code

　　类功能控制块：

<#+ 
public class OracleHelper
    {

        private static string oracleConnectionStr = "DATA SOURCE=testPRO;USER ID=APP;PASSWORD=APP;";
        public static DataTable ExecuteDataTable(string sql, params OracleParameter[] paramList)
        {
            using (OracleConnection conn = new OracleConnection(oracleConnectionStr))
            {
                conn.Open();
                using (OracleCommand command = conn.CreateCommand())
                {
                    command.CommandText = sql;
                    command.Parameters.AddRange(paramList);
                    DataTable dt = new DataTable();
                    OracleDataAdapter adapter = new OracleDataAdapter(command);
                    adapter.Fill(dt);
                    return dt;
                }
            }
        }

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

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

 #>
View Code

更多的T4模板语法参考 https://docs.microsoft.com/zh-cn/visualstudio/modeling/code-generation-and-t4-text-templates?view=vs-2015

参考：https://www.cnblogs.com/fenglingyi/p/5927082.html

　　　https://www.cnblogs.com/maiaimei/p/8994552.html

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原文地址：https://www.cnblogs.com/ZJ199012/p/12009781.html