C# T4模板在项目中的使用
1.什么是t4模版
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。在 Visual Studio 中，“T4 文本模板”是由一些文本块和控制逻辑组成的混合模板，它可以生成文本文件。 在 Visual C# 或 Visual Basic 中，控制逻辑编写为程序代码的片段。生成的文件可以是任何类型的文本，例如网页、资源文件或任何语言的程序源代码。现在的VS中只要与代码生成相关的场景基本上都能找T4的身影，比如MVC的视图模板，Entity Framwork的DataContext模板等等。
可以所T4模版课快速帮你生产实体类或者需要重复编写但是格式一致的代码
2.T4模版初试篇
首先看下运行效果:
我这手里有一个还没有编写实体类的项目，我们拿则个项目来测试下t4模版的强大之处
(1)首先我先新创建一个类库专门存放t4模版
(2)新创建一个 DbHelper.ttinclude 模板，主要是数据库操作类
<#+
public class config
{
public static readonly string ConnectionString = "Server=.;Database=XXXX;User ID=sa;Password=你的数据库密码";
public static readonly string DbDatabase = "";
public static readonly string TableName = "";
}
#>
<#+
public class DbHelper
{
#region GetDbTables
public static List<string> GetDbTablesNew(string connectionString, string database,string tables = null)
{
if (!string.IsNullOrEmpty(tables))
{
tables = string.Format(" and obj.name in ('{0}')", tables.Replace(",", "','"));
}
string sql = string.Format(@"SELECT
obj.name tablename
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
left join {0}.sys.extended_properties g ON (obj.object_id = g.major_id AND g.minor_id = 0 AND g.name= 'MS_Description')
where type='U' {1}
order by obj.name", database,tables);
DataTable dt = GetDataTable(connectionString, sql);
return dt.Rows.Cast<DataRow>().Select(row =>row.Field<string>("tablename")).ToList();
}
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"),
Precision=row.Field<int>("Precision"),
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 GetPrimaryKey
public static string GetPrimaryKey(List<DbColumn> dbColumns)
{
string primaryKey = string.Empty;
if (dbColumns!=null&&dbColumns.Count>0)
{
foreach (var item in dbColumns)
{
if (item.IsPrimaryKey==true)
{
primaryKey = item.ColumnName;
}
}
}
return primaryKey;
}
#endregion
}
#region DbTable
public sealed class DbTable
{
public string TableName { get; set; }
public string SchemaName { get; set; }
public int Rows { get; set; }
public bool HasPrimaryKey { get; set; }
}
#endregion
#region DbColumn
public sealed class DbColumn
{
public int ColumnID { get; set; }
public bool IsPrimaryKey { get; set; }
public string ColumnName { get; set; }
public string ColumnType { get; set; }
public string CSharpType
{
get
{
return SqlServerDbTypeMap.MapCsharpType(ColumnType);
}
}
/// <summary>
///
/// </summary>
public Type CommonType
{
get
{
return SqlServerDbTypeMap.MapCommonType(ColumnType);
}
}
public int ByteLength { get; set; }
public int CharLength { get; set; }
public int Precision{get;set;}
public int Scale { get; set; }
public bool IsIdentity { get; set; }
public bool IsNullable { get; set; }
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
#>(3)再创建一个 ModelAuto.ttinclude 实体类生产模版
<#@ 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 int Start, Length;
public String Name,OutputPath;
}
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 Manager(ITextTemplatingEngineHost host, StringBuilder template, bool commonHeader) {
this.host = host;
this.template = template;
strategy = ManagementStrategy.Create(host);
}
public void StartBlock(String name,String outputPath) {
currentBlock = new Block { Name = name, Start = template.Length ,OutputPath=outputPath};
}
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(block.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;
}
}
}
}#>
(3)创建实体类运行时文本模版
<#@ template debug="false" hostspecific="true" language="C#" #>
<#@ output extension="/" #>
<#@ 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="$(ProjectDir)DbHelper.ttinclude" #>
<#@ include file="$(ProjectDir)ModelAuto.ttinclude" #>
<# var manager = new Manager(Host, GenerationEnvironment, true); #>
<#
var OutputPath1 =Path.GetDirectoryName(Path.GetDirectoryName(Path.GetDirectoryName(Host.TemplateFile+"..")+"..")+"..");
OutputPath1=Path.Combine(OutputPath1,"H5.Framwork","Models_New");
if (!Directory.Exists(OutputPath1))
{
Directory.CreateDirectory(OutputPath1);
}
#>
<# foreach (var item in DbHelper.GetDbTablesNew(config.ConnectionString, config.DbDatabase,config.TableName))
{
var tableName=item.ToString();
manager.StartBlock(tableName+".cs",OutputPath1);//文件名
#>
using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace H5.Framwork.Model
{
///<summary>
///<#=tableName#>
///</summary>
[Table("<#=tableName#>")]
public class <#=tableName#>
{
<# foreach(DbColumn column in DbHelper.GetDbColumns(config.ConnectionString, config.DbDatabase, tableName)){#>
/// <summary>
/// <#= column.Remark == "" ? column.ColumnName : column.Remark.Replace("\r\n"," ") #>
/// </summary>
<#
if(column.IsPrimaryKey)
{#>[Key]
<#}#><# if(!column.IsNullable) {#>[Required]
<# }#>public <#= column.CSharpType#><# if(column.CommonType.IsValueType && column.IsNullable){#>?<#}#> <#=column.ColumnName#> { get; set; }
<#
}
#>
}
}
<#
manager.EndBlock();
}
manager.Process(true);
#>我们这里是在同个项目中的Models_New文件夹生产实体类
最后只需右键运行自定义工具就可以快速生成实体类了，运行代码上面的gif图所示
当然t4模版不仅仅只能生成实体类还能生产其他固定代码，其他的我们下一次来讲解
