ASP.NET MVC5+EF6+EasyUI 后台管理系统(29)-T4模版
本节不再适合本系统,在58,59节已经重构。请超过本节
这讲适合所有的MVC程序
之前我们发布了一个简单的代码生成器,其原理就是读取数据库的表结构,生成文本的一个方式来生成代码!
为了替代重复的劳动,微软自己有一套T4模版,我不想把T4模版说得那么的复杂,因为这个复杂我自己也不知道。
原理跟市面的代码生成器一个道理,但是T4的扩展比代码生成器更灵活,可以更方便根据类生成代码等操作。
T4代码模式是没有颜色高亮了,但是我们的VS支持插件 T4 Editor
下载安装之后就可以跟我们写C#一样有智能高亮和提示了。
新建一个项目,专门用于T4的存放。
首先我们要让T4连接我们的数据库
新建一个DbHelper.ttinclude模版包含文件
<#+ 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 #>
这里面包含了一些转换的方法和访问数据库的SQL语句
其中GetDbTables方法就是根据数据库的链接,表名来读取字段数据
怎么用呢?就是让模版包含这个文件,就可以访问方法了
举一个Model为例吧,新建Model文件夹。并新建文件,模版文件为tt结尾的扩展
我们新建Test.tt之后
<#@ template debug="false" hostspecific="false" language="C#" #> <#@ assembly name="System.Core" #> <#@ import namespace="System.Linq" #> <#@ import namespace="System.Text" #> <#@ import namespace="System.Collections.Generic" #> <#@ output extension=".txt" #>
最后一行<#@ output extension=".txt" #>
为模版生成的文件,可以是.cs可以是其他。我们就不改了,就是txt
如果是cs类,生成会编译,如果代码是对的,但是系统不知道是对的,会编译出错,虽然这不影响结果,但是不爽
我们为Test.tt添加如下代码
<#@ template debug="false" hostspecific="false" language="C#" #> <#@ output extension=".txt" #> <#@ 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="$(ProjectDir)DbHelper.ttinclude" #> //------------------------------------------------------------------------------ // <auto-generated> // 此代码由T4模板自动生成 // 生成时间 <#=DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")#> by YmNets // 对此文件的更改可能会导致不正确的行为,并且如果 // 重新生成代码,这些更改将会丢失。 // </auto-generated> //------------------------------------------------------------------------------
我们引入了一些命名空间,因为我们要将读到的表结构进行一系列的处理,比如for循环等操作
其中<#@ include file="$(ProjectDir)DbHelper.ttinclude" #>就是包含了刚刚简历的访问数据库文件
T4模版的语法通过上面我们可以看出是<#@#>,<#=#>,<##>,<#+#>结构跟原生的asp.net一个鸟样,不是Razor语法,这里要注意
我们添加一些代码
<#@ template debug="false" hostspecific="false" language="C#" #> <#@ output extension=".txt" #> <#@ 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 YmNets // 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; using System.ComponentModel.DataAnnotations; namespace <#=config.nameSpace#> { public class <#=config.TableName#>Model { <# foreach(DbColumn column in DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, config.TableName)){#> public <#= column.CSharpType#><# if(column.CommonType.IsValueType && column.IsNullable){#>?<#}#> <#=column.ColumnName#> { get; set; } <#}#> } } <#+ public class config { public static readonly string ConnectionString="Data Source=(local);Initial Catalog=AppDB;User ID=sa;Password=zhaoyun123!@#;"; public static readonly string DbDatabase="AppDB"; public static readonly string TableName="SysSample"; public static readonly string nameSpace="App.Sys"; } #>
有一些通用的我建了一个类config,访问config只需要config.TableName即可
访问DbHelper.ttinclude,值需要DbHelper.***即可
所以同道理,通用的类我们可以建造 Common.ttinclude来完善模版生成库
OK。配置好之后,值需要展开Test.tt就可以看到Test.txt文件,文件生成情况如下
//------------------------------------------------------------------------------ // <auto-generated> // 此代码由T4模板自动生成 // 生成时间 2014-03-03 17:34:45 by YmNets // 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; using System.ComponentModel.DataAnnotations; namespace App.Sys { public class SysSampleModel { public string Id { get; set; } public string Name { get; set; } public int? Age { get; set; } public DateTime? Bir { get; set; } public string Photo { get; set; } public string Note { get; set; } public DateTime? CreateTime { get; set; } } }
非常快速,所以,你可以很快建立自己项目的模版文件了。
以上只是基础,我们更加关心的是更多的扩展,比如判断数据库类型啊等等,做逻辑处理,获取字段的长度做处理啊。
所以我给大家提供一个备注:下面这条语句可以得到表的结构
<# foreach(DbColumn column in DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, config.TableName)){#> <#}#>
其中:
column.CSharpType 字段的类型
column.IsNullable 是否为空
column.IsPrimaryKey 是否是主键
column.CharLength 字段的长度,如varchar(50)那么column.CharLength=50
column.ColumnName 字段的名称
样例:判断是否DataTime类型
<#if(column.CSharpType=="DateTime"){#>
<# } #>
一个小小的例子,我们就能看懂MVC的T4模版,并能熟练运用它
出处:http://ymnets.cnblogs.com/
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