獲得的NullReferenceException在.NET Web應用程序創建的SqlConnection

Question

我得到在我的web應用程序中的System.NullReferenceException例外：

[NullReferenceException: Object reference not set to an instance of an object.] 
Home..ctor() in D:\Hosting\9651310\html\Home.aspx.vb:6 
ASP.home_aspx..ctor() in D:\Hosting\9651310\html\Home.aspx.vb:912304 
__ASP.FastObjectFactory_app_web_2ocmh1tt.Create_ASP_home_aspx() +47 
System.Web.Compilation.BuildResultCompiledType.CreateInstance() +32 
System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp) +109 
System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath) +31 
System.Web.UI.PageHandlerFactory.GetHandler(HttpContext context, String requestType, String virtualPath, String path) +37 
System.Web.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +334 
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184 

下面是拋出異常的行：

Dim con As New SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings("Connection").ToString()) 

的連接字符串部分我的web.config文件如下所示：

<connectionStrings> 
    <add name="ApplicationServices" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient" /> 
</connectionStrings> 

Answer 1

You ha連接字符串的名稱錯誤。更改以下行：

Dim con As New SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings("Connection").ToString()) 

要這樣：

Dim con As New SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings("ApplicationServices").ToString())