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  • T4模板根据DB生成实体类

    1.前言

    为什么会有这篇文章了,最近看到了一些框架,里面要写的代码太多了,故此就想偷懒,要是能写出一个T4模板,在数据库添加表后,根据模板就可以自动生成了类文件了,这样多好,心动不如行动。记得使用T4模板还是2年前,那个时候听波波老师讲课做我们的最后一个大项目CRM,简简单单的写了一下模板,保存一下,所有的类文件就出来了,当时那个膜拜,油然而生。

     同时在工作中,我们公司自己开发的一个ORM,实体类都要自己写,一个数据库表的字段太多,写的真是手抽筋。如果你对T4基础语法不是很了解,可以参考我前面写的一篇文章 T4语法快速入门

    2.原理

    我们要做的事情是通过数据库表生成实体类。

    第一步 我们要查询出当前用户下的所有数据库表。

    第二步 查询出数据库表的结构,比如字段的名称,字段的类型,字段的长度大小,是否为空等等。

    工作中oracle用的比较多,在这里我就分析oracle和mssql

    3.oracle

    查询当前用户所有的表。

    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 = 'AFFIXINFO'

     ModelAuto.ttinclude来源与网上,作用是生成一个一个单独的类文件,即xx.cs文件。

    <#@ 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;
                }
            }
        }
    }#>
    ModelAuto.ttinclude
    <#@ template debug="true" hostspecific="true" language="C#" #>
    <#@ output extension=".cs" #>
    <#@ assembly name="System.Data" #>
    <#@ assembly name="System.Data.OracleClient" #>
    <#@ assembly name="System.Xml" #>
    <#@ import namespace="System" #>
    <#@ import namespace="System.Xml" #>
    <#@ import namespace="System.Data" #>
    <#@ import namespace="System.Data.OracleClient" #>
    <#@ 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;
    using System.Data;
    using System.Data.OracleClient;
    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 = "Data Source=orcl;Persist Security Info=True;User ID=jjmis;Password=jjmis;Unicode=True";
            /// <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; } /// <summary> /// SQL[不完善,需要的自己改造] /// </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 = "Data Source=orcl;Persist Security Info=True;User ID=jjmis;Password=jjmis;Unicode=True"; 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(); } } } } #>

     保存此模板文件就可以生成下面类文件。

     4.Mssql

    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'

    同样我们要生成多个类文件,需要引入 ModelAuto.ttinclude

    ModelTemplate.tt文件如下

    <#@ 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=NFineBase;User ID=sa;Password=hjf19870810;"; 
        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);
    #>

    保存ModelTemplate.tt就可以得到类文件。

    文章中的源代码在此次下载

    1.T4语法快速入门

    2.T4模板根据DB生成实体类

    3.NFine框架的T4模板

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  • 原文地址:https://www.cnblogs.com/fenglingyi/p/5927082.html
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