变化的实体连接字符串错误

Question

，我改变了模型实体connection string时，有一个问题，
当KurtDBEntitiesconection string用户首次登录被适当地选择
但登录以管理员if (daRoles.IsUserInRole(User, 1))或任何其他情况下它的时候是给我这个错误：

System.InvalidOperationException was unhandled by user code 
    Message=No modifications to connection are permitted after the metadata has been registered either by opening a connection or constructing the connection with a MetadataWorkspace. 
    Source=System.Data.Entity 
    StackTrace: 
     at System.Data.EntityClient.EntityConnection.ValidateChangesPermitted() 
     at System.Data.EntityClient.EntityConnection.set_ConnectionString(String value) 
     at DataLayer.ConnectionClass..ctor(String User) in Documents\Visual Studio 2010\Projects\DataLayer\ConnectionClass.cs:line 32 
     at BusinessLayer.BLBase..ctor(String user) in Documents\Visual Studio 2010\Projects\BusinessLayer\BLBase.cs:line 54 
     at BusinessLayer.Roles..ctor(String userLogged) in Visual Studio 2010\Projects\BusinessLayer\Roles.cs:line 12 
     at PresentationLayer.UserControls.Menu.Page_Load(Object sender, EventArgs e) in C:\Users\Documents\Visual Studio 2010\Projects\PresentationLayer\UserControls\Menu.ascx.cs:line 23 
     at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) 
     at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) 
     at System.Web.UI.Control.OnLoad(EventArgs e) 
     at System.Web.UI.Control.LoadRecursive() 
     at System.Web.UI.Control.LoadRecursive() 
     at System.Web.UI.Control.LoadRecursive() 
     at System.Web.UI.Control.LoadRecursive() 
     at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) 
    InnerException: 

和：

public ConnectionClass(string User) 
     { 

      this.Entities = new KurtDBEntities(); 
      DataLayer.DARoles daRoles = new DARoles(this.Entities); 
      if (User == "Login") 

     { 
      this.Entities.Connection.ConnectionString = ConfigurationManager.ConnectionStrings["KurtDBEntities"].ConnectionString.ToString(); 
     } 
     else 
     { 
      //can also use entity connection string builder 

      if (User != "") 
      { 
       if (daRoles.IsUserInRole(User, 1)) 
       { 

        this.Entities.Connection.ConnectionString = @"Data Source=KURT-PC\SQLEXPRESS;Initial Catalog=KurtDB;User ID=Admin;Password=123456"; 
       } 
       else if (daRoles.IsUserInRole(User, 2)) 
       { 
        this.Entities.Connection.ConnectionString = ConfigurationManager.ConnectionStrings["BasicUser"].ConnectionString.ToString(); 
       } 

      } 
      else 
      { 
       this.Entities.Connection.ConnectionString = ConfigurationManager.ConnectionStrings["KurtDBEntities"].ConnectionString.ToString(); 
      } 

     } 


     //this.Entities.Connection.ConnectionString = conn; 
    } 

}

任何帮助请吗？

Answer 1

请参阅my answer to your other question：

你需要首先确定要使用，之后才是你就可以到新的了实体对象连接字符串：

string connectionString = GetConnectionStringBasedOnUserRole(); // do your magic here 
this.Entities = new KurtDBEntities(connectionString); 

在此之后，您应该能够正常使用实体，指向正确的数据库/服务器。