c# – 如何在T4中实例化EF6上下文？

我想在T4模板中实例化一个新的EF6上下文,但是我收到以下错误：

system.invalidOperationException: The ‘Instance’ member of the Entity Framework provider type ‘System.Data.Entity.sqlServer.sqlProviderServices,EntityFramework.sqlServer,Version=6.0.0.0,Culture=neutral,PublicKeyToken=b77a5c561934e089’ did not return an object that inherits from ‘System.Data.Entity.Core.Common.DbProviderServices’. Entity Framework providers must inherit from this class and the ‘Instance’ member must return the singleton instance of the provider.

解决方法

问题是无法实例化实体框架上下文,因为无法读取连接字符串.

我做了以下以获取连接字符串：

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

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

但请确保您已导入以下内容以使上述代码正常工作：

<#@ import namespace="Microsoft.VisualStudio.TextTemplating" #>
<#@ import namespace="System.Configuration" #>
<#@ import namespace="System" #>

还要确保已引用所有实体框架程序集：

<#@ assembly name="$(MSBuildProjectDirectory)\bin\EntityFramework.dll" #>
<#@ assembly name="$(MSBuildProjectDirectory)\bin\EntityFramework.sqlServer.dll" #>

<#@ assembly name="System.Core.dll" #>
<#@ assembly name="System.Configuration" #>
<#@ assembly name="System.Data.dll" #>