如何使T4模板可用连接字符串？ [英] How to make connection strings available in a T4 template?

问题描述

我写，我实例化一个EF上下文来读取一些数据的T4模板。
的问题是，上下文无法看到从Web.config的连接字符串。

如何使从Web.config连接字符串提供给？模板

更多信息：

• 模板从头开始编写


• EF EDMX位于另一个项目


• 我做模板第一个查询告诉我，它无法找到所需的连接字符串中的项目，其中模板所在

---

尝试下面的一些解决方案（谢谢），但我得到这个

 错误2编译转型：Microsoft.VisualStudio.TextTemplating12165CB53B43A726CBA54A29800255D257AAFD4D5F0DACE4DFE5872F2DEC7739EDF358F49C0444A912B851939903A79BC6180FCEB3FD0D1BF8C0093741DDDACA.GeneratedTextTransformation'不包含'主机'和一个没有定义扩展方法主机接受型Microsoft.VisualStudio.TextTemplating12165CB53B43A726CBA54A29800255D257AAFD4D5F0DACE4DFE5872F2DEC7739EDF358F49C0444A912B851939903A79BC6180FCEB3FD0D1BF8C0093741DDDACA.GeneratedTextTransformation'的第一个参数可以找到（是否缺少using指令或程序集引用？）
  

我有以下声明：

 <＃@总成NAME =EnvDTE＃> 
<＃@导入命名空间=EnvDTE＃> 
<＃@导入命名空间=Microsoft.VisualStudio.TextTemplating＃> 
  

如果我包括大会Microsoft.VisualStudio.TextTemplating它告诉我，它已经插入。

此外，有没有什么办法能让ConfigurationManager中提供给的DbContext这样他就可以读W / E，他希望没有我在幕后通过他的连接字符串后面？

---

解决了，再次感谢：

 <＃@模板hostspecific =真LANGUAGE =C＃调试=假＃> 
<＃@集名称=System.Core.dll＃> 
<＃@集名称=System.Configuration＃> 
<＃@导入命名空间=Microsoft.VisualStudio.TextTemplating＃> 
<＃@导入命名空间=System.Configuration＃> 
 
 VAR地图=新ExeConfigurationFileMap（）; 
 map.ExeConfigFilename = this.Host.ResolvePath（@.. \Web.config）; 
 
无功配置= ConfigurationManager.OpenMappedExeConfiguration（地图，ConfigurationUserLevel.None）; 
变种的connectionString = config.ConnectionStrings.ConnectionStrings [MyConnectionName]的ConnectionString。 
  

解决方案

我访问的连接字符串从App.config中从T4模板在接下来的方式：

 <＃@模板调试=假hostspecific =真LANGUAGE =C＃ ＃> 
 
 ExeConfigurationFileMap configFileMap =新ExeConfigurationFileMap（this.Host.ResolvePath（@.. \ProjName\App.config））; 
 configFileMap.ExeConfigFilename = this.Host.ResolvePath（@.. \ProjName\App.config）; 
配置配置= ConfigurationManager.OpenMappedExeConfiguration（configFileMap，ConfigurationUserLevel.None）; 
字符串的connectionString = config.ConnectionStrings.ConnectionStrings [0] .ConnectionString; 
  

I've written a T4 template where I instantiate an EF context to read some data. The problem is that the context cannot see the connection string from the Web.config.

How can I make the connection strings from the Web.config available to the template?

More info:

• template is written from scratch
• EF edmx is located in another project
• the first query I make in the template tells me that it cannot find the required connection string in the project where the template resides

---

Tried some of the solutions (thank you) below but I get this:

Error 2 Compiling transformation: 'Microsoft.VisualStudio.TextTemplating12165CB53B43A726CBA54A29800255D257AAFD4D5F0DACE4DFE5872F2DEC7739EDF358F49C0444A912B851939903A79BC6180FCEB3FD0D1BF8C0093741DDDACA.GeneratedTextTransformation' does not contain a definition for 'Host' and no extension method 'Host' accepting a first argument of type 'Microsoft.VisualStudio.TextTemplating12165CB53B43A726CBA54A29800255D257AAFD4D5F0DACE4DFE5872F2DEC7739EDF358F49C0444A912B851939903A79BC6180FCEB3FD0D1BF8C0093741DDDACA.GeneratedTextTransformation' could be found (are you missing a using directive or an assembly reference?)

I have the following declared:

<#@ assembly name="EnvDTE" #>
<#@ import namespace="EnvDTE" #>
<#@ import namespace="Microsoft.VisualStudio.TextTemplating" #>

If I include the assembly for Microsoft.VisualStudio.TextTemplating it tells me that it's already inserted.

Also, is there any way to make the ConfigurationManager available to the DbContext so he can read w/e he wants behind the scenes without me passing him the connection string?

---

Solved it, thanks again:

<#@ template hostspecific="true" language="C#" debug="false" #>
<#@ assembly name="System.Core.dll" #>
<#@ assembly name="System.Configuration" #>
<#@ import namespace="Microsoft.VisualStudio.TextTemplating" #>
<#@ import namespace="System.Configuration" #>

var map = new ExeConfigurationFileMap();
map.ExeConfigFilename = this.Host.ResolvePath(@"..\Web.config");

var config = ConfigurationManager.OpenMappedExeConfiguration(map, ConfigurationUserLevel.None);
var connectionString = config.ConnectionStrings.ConnectionStrings["MyConnectionName"].ConnectionString;

解决方案

I accessed a connection string from App.config from T4 template in the next way:

<#@ template debug="false" hostspecific="true" language="C#" #>

ExeConfigurationFileMap configFileMap = new ExeConfigurationFileMap(this.Host.ResolvePath(@"..\ProjName\App.config"));
configFileMap.ExeConfigFilename = this.Host.ResolvePath(@"..\ProjName\App.config");
Configuration config = ConfigurationManager.OpenMappedExeConfiguration(configFileMap, ConfigurationUserLevel.None);
string connectionString = config.ConnectionStrings.ConnectionStrings[0].ConnectionString;

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