T4模版引擎之生成数据库实体类

工欲善其事必先利其器,在这之前先来介绍一款T4编辑器T4 Editor,我们可以点击链接去下载然后安装,不过还是推荐大家直接在VS扩展管理器里直接安装来的方便 工具->扩展管理器->联机库 搜索 "T4 Editor",选择第一项 "tangible T4 Editor 2.0 plus modeling tools for VS2010" 进行安装即可,如下图所示:

安装上T4 Editor后,编辑T4模板是就有代码着色和智能提示了,下图为安装T4 Editor后的代码着色效果,怎么样是不是耳目一新,呵呵

 

 

接下来开始正式进入我们的主题,从数据库自动生成实体类

  1. 新建一个控制台项目,然后添加T4模板,这里我们起名字为Customers.tt

  2. 修改输出文件扩展名为.cs
    <#@ output extension=".cs" #>
  3. 添加常用的程序集和命名空间引用
    复制代码
    <#@ assembly name="System.Core.dll" #>
    <#@ assembly name="System.Data.dll" #>
    <#@ assembly name="System.Data.DataSetExtensions.dll" #>
    <#@ assembly name="System.Xml.dll" #>
    <#@ import namespace="System" #>
    <#@ import namespace="System.Xml" #>
    <#@ import namespace="System.Linq" #>
    <#@ import namespace="System.Data" #>
    <#@ import namespace="System.Data.SqlClient" #>
    <#@ import namespace="System.Collections.Generic" #>
    <#@ import namespace="System.IO" #>
    复制代码
  4. 添加数据库操作DbHelper引用
    复制代码
    <#+
        public class DbHelper
        {
            #region GetDbTables
            
            public static List<DbTable> GetDbTables(string connectionString, string database, string tables = null)
            {
                
                if (!string.IsNullOrEmpty(tables))
                {
                    tables = string.Format(" and obj.name in ('{0}')", tables.Replace(",", "','"));
                }
                #region SQL
                string sql = string.Format(@"SELECT
                                        obj.name tablename,
                                        schem.name schemname,
                                        idx.rows,
                                        CAST
                                        (
                                            CASE 
                                                WHEN (SELECT COUNT(1) FROM sys.indexes WHERE object_id= obj.OBJECT_ID AND is_primary_key=1) >=1 THEN 1
                                                ELSE 0
                                            END 
                                        AS BIT) HasPrimaryKey                                         
                                        from {0}.sys.objects obj 
                                        inner join {0}.dbo.sysindexes idx on obj.object_id=idx.id and idx.indid<=1
                                        INNER JOIN {0}.sys.schemas schem ON obj.schema_id=schem.schema_id
                                        where type='U' {1}
                                        order by obj.name", database, tables);
                #endregion
                DataTable dt = GetDataTable(connectionString, sql);
                return dt.Rows.Cast<DataRow>().Select(row => new DbTable
                {
                    TableName = row.Field<string>("tablename"),
                    SchemaName = row.Field<string>("schemname"),
                    Rows = row.Field<int>("rows"),
                    HasPrimaryKey = row.Field<bool>("HasPrimaryKey")
                }).ToList();
            }
            #endregion
    
            #region GetDbColumns
            
            public static List<DbColumn> GetDbColumns(string connectionString, string database, string tableName, string schema = "dbo")
            {
                #region SQL
                string sql = string.Format(@"
                                        WITH indexCTE AS
                                        (
                                            SELECT 
                                            ic.column_id,
                                            ic.index_column_id,
                                            ic.object_id    
                                            FROM {0}.sys.indexes idx
                                            INNER JOIN {0}.sys.index_columns ic ON idx.index_id = ic.index_id AND idx.object_id = ic.object_id
                                            WHERE  idx.object_id =OBJECT_ID(@tableName) AND idx.is_primary_key=1
                                        )
                                        select
                                        colm.column_id ColumnID,
                                        CAST(CASE WHEN indexCTE.column_id IS NULL THEN 0 ELSE 1 END AS BIT) IsPrimaryKey,
                                        colm.name ColumnName,
                                        systype.name ColumnType,
                                        colm.is_identity IsIdentity,
                                        colm.is_nullable IsNullable,
                                        cast(colm.max_length as int) ByteLength,
                                        (
                                            case 
                                                when systype.name='nvarchar' and colm.max_length>0 then colm.max_length/2 
                                                when systype.name='nchar' and colm.max_length>0 then colm.max_length/2
                                                when systype.name='ntext' and colm.max_length>0 then colm.max_length/2 
                                                else colm.max_length
                                            end
                                        ) CharLength,
                                        cast(colm.precision as int) Precision,
                                        cast(colm.scale as int) Scale,
                                        prop.value Remark
                                        from {0}.sys.columns colm
                                        inner join {0}.sys.types systype on colm.system_type_id=systype.system_type_id and colm.user_type_id=systype.user_type_id
                                        left join {0}.sys.extended_properties prop on colm.object_id=prop.major_id and colm.column_id=prop.minor_id
                                        LEFT JOIN indexCTE ON colm.column_id=indexCTE.column_id AND colm.object_id=indexCTE.object_id                                        
                                        where colm.object_id=OBJECT_ID(@tableName)
                                        order by colm.column_id", database);
                #endregion
                SqlParameter param = new SqlParameter("@tableName", SqlDbType.NVarChar, 100) { Value = string.Format("{0}.{1}.{2}", database, schema, tableName) };
                DataTable dt = GetDataTable(connectionString, sql, param);
                return dt.Rows.Cast<DataRow>().Select(row => new DbColumn()
                {
                    ColumnID = row.Field<int>("ColumnID"),
                    IsPrimaryKey = row.Field<bool>("IsPrimaryKey"),
                    ColumnName = row.Field<string>("ColumnName"),
                    ColumnType = row.Field<string>("ColumnType"),
                    IsIdentity = row.Field<bool>("IsIdentity"),
                    IsNullable = row.Field<bool>("IsNullable"),
                    ByteLength = row.Field<int>("ByteLength"),
                    CharLength = row.Field<int>("CharLength"),
                    Scale = row.Field<int>("Scale"),
                    Remark = row["Remark"].ToString()
                }).ToList();
            }
    
            #endregion     
    
    
            #region GetDataTable
            
            public static DataTable GetDataTable(string connectionString, string commandText, params SqlParameter[] parms)
            {
                using (SqlConnection connection = new SqlConnection(connectionString))
                {
                    SqlCommand command = connection.CreateCommand();
                    command.CommandText = commandText;
                    command.Parameters.AddRange(parms);
                    SqlDataAdapter adapter = new SqlDataAdapter(command);
    
                    DataTable dt = new DataTable();
                    adapter.Fill(dt);
    
                    return dt;
                }
            }
    
            #endregion
        }
    
        #region DbTable
        /// <summary>
        /// 表结构
        /// </summary>
        public sealed class DbTable
        {
            /// <summary>
            /// 表名称
            /// </summary>
            public string TableName { get; set; }
            /// <summary>
            /// 表的架构
            /// </summary>
            public string SchemaName { get; set; }
            /// <summary>
            /// 表的记录数
            /// </summary>
            public int Rows { get; set; }
    
            /// <summary>
            /// 是否含有主键
            /// </summary>
            public bool HasPrimaryKey { get; set; }
        }
        #endregion
    
        #region DbColumn
        /// <summary>
        /// 表字段结构
        /// </summary>
        public sealed class DbColumn
        {
            /// <summary>
            /// 字段ID
            /// </summary>
            public int ColumnID { get; set; }
    
            /// <summary>
            /// 是否主键
            /// </summary>
            public bool IsPrimaryKey { get; set; }
    
            /// <summary>
            /// 字段名称
            /// </summary>
            public string ColumnName { get; set; }
    
            /// <summary>
            /// 字段类型
            /// </summary>
            public string ColumnType { get; set; }
    
            /// <summary>
            /// 数据库类型对应的C#类型
            /// </summary>
            public string CSharpType
            {
                get
                {
                    return SqlServerDbTypeMap.MapCsharpType(ColumnType);
                }
            }
    
            /// <summary>
            /// 
            /// </summary>
            public Type CommonType
            {
                get
                {
                    return SqlServerDbTypeMap.MapCommonType(ColumnType);
                }
            }
    
            /// <summary>
            /// 字节长度
            /// </summary>
            public int ByteLength { get; set; }
    
            /// <summary>
            /// 字符长度
            /// </summary>
            public int CharLength { get; set; }
    
            /// <summary>
            /// 小数位
            /// </summary>
            public int Scale { get; set; }
    
            /// <summary>
            /// 是否自增列
            /// </summary>
            public bool IsIdentity { get; set; }
    
            /// <summary>
            /// 是否允许空
            /// </summary>
            public bool IsNullable { get; set; }
    
            /// <summary>
            /// 描述
            /// </summary>
            public string Remark { get; set; }
        }
        #endregion
    
        #region SqlServerDbTypeMap
    
        public class SqlServerDbTypeMap
        {
            public static string MapCsharpType(string dbtype)
            {
                if (string.IsNullOrEmpty(dbtype)) return dbtype;
                dbtype = dbtype.ToLower();
                string csharpType = "object";
                switch (dbtype)
                {
                    case "bigint": csharpType = "long"; break;
                    case "binary": csharpType = "byte[]"; break;
                    case "bit": csharpType = "bool"; break;
                    case "char": csharpType = "string"; break;
                    case "date": csharpType = "DateTime"; break;
                    case "datetime": csharpType = "DateTime"; break;
                    case "datetime2": csharpType = "DateTime"; break;
                    case "datetimeoffset": csharpType = "DateTimeOffset"; break;
                    case "decimal": csharpType = "decimal"; break;
                    case "float": csharpType = "double"; break;
                    case "image": csharpType = "byte[]"; break;
                    case "int": csharpType = "int"; break;
                    case "money": csharpType = "decimal"; break;
                    case "nchar": csharpType = "string"; break;
                    case "ntext": csharpType = "string"; break;
                    case "numeric": csharpType = "decimal"; break;
                    case "nvarchar": csharpType = "string"; break;
                    case "real": csharpType = "Single"; break;
                    case "smalldatetime": csharpType = "DateTime"; break;
                    case "smallint": csharpType = "short"; break;
                    case "smallmoney": csharpType = "decimal"; break;
                    case "sql_variant": csharpType = "object"; break;
                    case "sysname": csharpType = "object"; break;
                    case "text": csharpType = "string"; break;
                    case "time": csharpType = "TimeSpan"; break;
                    case "timestamp": csharpType = "byte[]"; break;
                    case "tinyint": csharpType = "byte"; break;
                    case "uniqueidentifier": csharpType = "Guid"; break;
                    case "varbinary": csharpType = "byte[]"; break;
                    case "varchar": csharpType = "string"; break;
                    case "xml": csharpType = "string"; break;
                    default: csharpType = "object"; break;
                }
                return csharpType;
            }
               
            public static Type MapCommonType(string dbtype)
            {
                if (string.IsNullOrEmpty(dbtype)) return Type.Missing.GetType();
                dbtype = dbtype.ToLower();
                Type commonType = typeof(object);
                switch (dbtype)
                {
                    case "bigint": commonType = typeof(long); break;
                    case "binary": commonType = typeof(byte[]); break;
                    case "bit": commonType = typeof(bool); break;
                    case "char": commonType = typeof(string); break;
                    case "date": commonType = typeof(DateTime); break;
                    case "datetime": commonType = typeof(DateTime); break;
                    case "datetime2": commonType = typeof(DateTime); break;
                    case "datetimeoffset": commonType = typeof(DateTimeOffset); break;
                    case "decimal": commonType = typeof(decimal); break;
                    case "float": commonType = typeof(double); break;
                    case "image": commonType = typeof(byte[]); break;
                    case "int": commonType = typeof(int); break;
                    case "money": commonType = typeof(decimal); break;
                    case "nchar": commonType = typeof(string); break;
                    case "ntext": commonType = typeof(string); break;
                    case "numeric": commonType = typeof(decimal); break;
                    case "nvarchar": commonType = typeof(string); break;
                    case "real": commonType = typeof(Single); break;
                    case "smalldatetime": commonType = typeof(DateTime); break;
                    case "smallint": commonType = typeof(short); break;
                    case "smallmoney": commonType = typeof(decimal); break;
                    case "sql_variant": commonType = typeof(object); break;
                    case "sysname": commonType = typeof(object); break;
                    case "text": commonType = typeof(string); break;
                    case "time": commonType = typeof(TimeSpan); break;
                    case "timestamp": commonType = typeof(byte[]); break;
                    case "tinyint": commonType = typeof(byte); break;
                    case "uniqueidentifier": commonType = typeof(Guid); break;
                    case "varbinary": commonType = typeof(byte[]); break;
                    case "varchar": commonType = typeof(string); break;
                    case "xml": commonType = typeof(string); break;
                    default: commonType = typeof(object); break;
                }
                return commonType;
            }
        }
        #endregion
        
    
    #>
    复制代码
    <#@ include file="$(ProjectDir)DbHelper.ttinclude"  #>

    DbHelper相对比较复杂,把一些常用操作进行了简单封装,因此放到一个单独的文件里面进行引用,可以方便的进行复用,这里DbHelper的后缀名使用ttinclude,这里的后缀名可以随便起,按照微软的建议:用于include的文件尽量不要使用.tt做后缀名

  5. 在页面底部定义一些常用变量,以方便操作
    复制代码
    <#+
        public class config
        {
            public static readonly string ConnectionString="Data Source=(local);Integrated Security=true;Initial Catalog=Northwind;";
            public static readonly string DbDatabase="Northwind";
            public static readonly string TableName="Customers";
        }
    #>
    复制代码

    这里我们把数据库连接串和数据库、表名字定义一下,方便修改和使用

  6. 最后来编写用于实体类生成的代码
    复制代码
    //------------------------------------------------------------------------------
    // <auto-generated>
    //     此代码由T4模板自动生成
    //       生成时间 <#=DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")#> by 懒惰的肥兔
    //     对此文件的更改可能会导致不正确的行为,并且如果
    //     重新生成代码,这些更改将会丢失。
    // </auto-generated>
    //------------------------------------------------------------------------------
    
    using System;
    namespace T4ConsoleApplication.Entities
    {    
    
        public class <#=config.TableName#>
        {
            <# foreach(DbColumn column in DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, config.TableName)){#>
    
            /// <summary>
            /// <#=column.Remark#>
            /// </summary>        
            public <#= column.CSharpType#><# if(column.CommonType.IsValueType && column.IsNullable){#>?<#}#> <#=column.ColumnName#> { get; set; }
            <#}#> 
          
        }
    }
    复制代码
  7. 全部完成后我们的Customers.tt文件就编写好了
    复制代码
    <#@ template debug="false" hostspecific="false" language="C#" #>
    <#@ output extension=".cs" #>
    <#@ assembly name="System.Core.dll" #>
    <#@ assembly name="System.Data.dll" #>
    <#@ assembly name="System.Data.DataSetExtensions.dll" #>
    <#@ assembly name="System.Xml.dll" #>
    <#@ import namespace="System" #>
    <#@ import namespace="System.Xml" #>
    <#@ import namespace="System.Linq" #>
    <#@ import namespace="System.Data" #>
    <#@ import namespace="System.Data.SqlClient" #>
    <#@ import namespace="System.Collections.Generic" #>
    <#@ import namespace="System.IO" #>
    <#@ include file="$(ProjectDir)DbHelper.ttinclude"  #>
    //------------------------------------------------------------------------------
    // <auto-generated>
    //     此代码由T4模板自动生成
    //       生成时间 <#=DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")#> by 懒惰的肥兔
    //     对此文件的更改可能会导致不正确的行为,并且如果
    //     重新生成代码,这些更改将会丢失。
    // </auto-generated>
    //------------------------------------------------------------------------------
    
    using System;
    namespace T4ConsoleApplication.Entities
    {    
    
        public class <#=config.TableName#>
        {
            <# foreach(DbColumn column in DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, config.TableName)){#>
    
            /// <summary>
            /// <#=column.Remark#>
            /// </summary>        
            public <#= column.CSharpType#><# if(column.CommonType.IsValueType && column.IsNullable){#>?<#}#> <#=column.ColumnName#> { get; set; }
            <#}#> 
          
        }
    }
    
    <#+
        public class config
        {
            public static readonly string ConnectionString="Data Source=(local);Integrated Security=true;Initial Catalog=Northwind;";
            public static readonly string DbDatabase="Northwind";
            public static readonly string TableName="Customers";
        }
    #>
    复制代码

    进行保存后会自动生成Customers.cs文件

    复制代码
    //------------------------------------------------------------------------------
    // <auto-generated>
    //     此代码由T4模板自动生成
    //       生成时间 2012-07-18 17:51:26 by 懒惰的肥兔
    //     对此文件的更改可能会导致不正确的行为,并且如果
    //     重新生成代码,这些更改将会丢失。
    // </auto-generated>
    //------------------------------------------------------------------------------
    
    using System;
    namespace T4ConsoleApplication.Entities
    {    
    
        public class Customers
        {
            
            /// <summary>
            /// 
            /// </summary>        
            public string CustomerID { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string CompanyName { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string ContactName { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string ContactTitle { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string Address { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string City { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string Region { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string PostalCode { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string Country { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string Phone { get; set; }
            
            /// <summary>
            /// 
            /// </summary>        
            public string Fax { get; set; }
             
          
        }
    }
    复制代码

     

      至此完整演示了怎样一步步根据数据库生成实体类的操作,是不是很简单,如对语法和操作不理解的地方可以参考T4模版引擎之基础入门,稍微用心研究下,轻松打造属于自己的代码生成器。

  本文简单介绍了基于单个模板生成数据库实体类的示例,离具体实用还有一定的距离,毕竟总不能为每个数据表建一个模板吧,下一篇将揭晓如何通过单个T4模板生成多个文件,以及自动生成整个数据库的所有实体类,敬请期待

  下班了,拍拍屁股走人。。。

源码:T4ConsoleApplication.rar

posted @ 2016-11-28 13:24 银河系上的地球 阅读(...) 评论(...) 编辑 收藏