T4语法快速入门
Posted 积少成多
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1.什么是T4?
T4，即4个T开头的英文字母组合：Text Template Transformation Toolkit。T4(Text Template Transformation Toolkit)是微软官方在VisualStudio 2008中开始使用的代码生成引擎。简单的说就是可以根据模板生成你想要的文件，可以使类文件,文本文件,html等等。
2.vs插件的安装
T4的编辑工具下载地址http://t4-editor.tangible-engineering.com/Download_T4Editor_Plus_ModelingTools.html
VS默认的编辑工具无高亮，无提示，错误不易定位。 没这个工具，真心不想写任何T4代码。
3.T4语法
<# 标准控制块 #> 可以包含语句。 <#= 表达式控制块 #> 可以包含表达式。 <#+ 类特征控制块 #> 可以包含方法、字段和属性，就像一个类的内部 <#@ 指令 属性=“值”#>
3.1.标准控制块
<#@ template debug="false" hostspecific="false" language="C#" #> <#@ import namespace="System" #> <#@ output extension=".txt" #> <# int a=10; string b = "20"; DateTime c = DateTime.Now; for(int i = 0; i < 4; i++) { #> 测试 <# } #>
3.2.表达式控制块
<#@ template debug="false" hostspecific="false" language="C#" #> <#@ import namespace="System" #> <#@ output extension=".txt" #> <# int a=10; string b = "20"; DateTime c = DateTime.Now; for(int i = 0; i < 4; i++) { #> 测试<#=i#> <#=string.Format("{0},{1},{2}",a,b,c)#> <# } #>
3.3.类特征控制块
<#@ template debug="false" hostspecific="false" language="C#" #> <#@ import namespace="System" #> <#@ import namespace="System.Collections.Generic" #> <#@ output extension=".txt" #> <# int a=10; string b = "20"; DateTime c = DateTime.Now; for(int i = 0; i < 4; i++) { #> 测试<#=i#> <#=string.Format("{0},{1},{2}",a,b,c)#> <#=1+1#> <#=config.TableName#> <# } #> <#+ public class config { public static readonly string ConnectionString = "Data Source=(local);Initial Catalog=NFineBase;User ID=sa;Password=hjf19870810;"; public static readonly string DbDatabase = "NFineBase"; public static readonly string TableName = "Sys_Test"; } #>
3.4.指令
<#@ output extension=".cs" #> 告诉T4引擎生成文件的后缀名是.cs； <#@ template debug="false" hostspecific="false" language="C#" #> langeuage:输出语言，有效值C#、VB，默认为C# debug:是否启用调试，有效值true、false，默认为false。 hostspecific:有效值true、false，默认为false。如果将此特性的值设置为 true，则会将名为 Host 的属性添加到由文本模板生成的类中。 该属性是对转换引擎的宿主的引用，并声明为Microsoft.VisualStudio.TextTemplating.ITextTemplatingEngineHost。 inherits：可以指定模板的程序代码可以继承自另一个类，这个类也可以从文本模板生成。目前木有使用过，基本上可以忽略 <#@ assembly name="System"#> 告诉T4引擎编译运行时引用System程序集 <#@ import namespace="System.Data"#> 告诉T4引擎编译运行时引用某个名称空间。
3.5.实战
<#+
public class DbHelper
{
public static readonly string connectionString="Data Source=GZPC0114;User ID=sa;Password=abc.123;persist security info=False;initial catalog=suibao_jz_db;";
//public static readonly string connectionString="Data Source=192.168.10.135;User ID=sa;Password=111111;persist security info=False;initial catalog=suibao_jz_db;";
public static readonly string database="suibao_jz_db";
#region GetDbTables
public static List<DbTable> GetDbTables()
{
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,
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}.sys.schemas schem ON obj.schema_id=schem.schema_id
where type=\'U\' or type=\'V\' {1}
order by obj.name", database, tables);
#endregion
DataTable dt = GetDataTable(sql);
return dt.Rows.Cast<DataRow>().Select(row => new DbTable
{
TableName = row.Field<string>("tablename"),
SchemaName = row.Field<string>("schemname"),
HasPrimaryKey = row.Field<bool>("HasPrimaryKey")
}).ToList();
}
#endregion
#region GetDbColumns
public static List<DbColumn> GetDbColumns(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(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 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;
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