Client Application Services with Visual Studio 2008

This video was great: fast paced yet complete.

I did spend a frustrating hour or so trying to figure out why, when I checked the "Remember Me" checkbox, the next call to Membership.ValidateUser(null, null) would result in an exception:

System.NullReferenceException was unhandled
  Message="Object reference not set to an instance of an object."
  Source="System.Web.Extensions"
  StackTrace:
       at System.Web.ClientServices.ClientFormsIdentity.GetSecureStringFromString(String password)
       at System.Web.ClientServices.Providers.ClientFormsAuthenticationMembershipProvider.ValidateUserCore(String username, String password, Int32 rememberMeInt, Int32& promptCount, Boolean tryToUseLastLoggedInUser)
       at System.Web.ClientServices.Providers.ClientFormsAuthenticationMembershipProvider.ValidateUserCore(String username, String password, Int32 rememberMeInt)
       at System.Web.ClientServices.Providers.ClientFormsAuthenticationMembershipProvider.ValidateUser(String username, String password)
       at System.Web.Security.Membership.ValidateUser(String username, String password)
       at AppServicesClient.Form1.Form1_Load(Object sender, EventArgs e) in C:\Users\drogers\Documents\Visual Studio 2008\Projects\AppServicesDemo\AppServicesClient\Form1.cs:line 39
       at System.Windows.Forms.Form.OnLoad(EventArgs e)
       at System.Windows.Forms.Form.OnCreateControl()
       at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
       at System.Windows.Forms.Control.CreateControl()
       at System.Windows.Forms.Control.WmShowWindow(Message& m)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
       at System.Windows.Forms.ContainerControl.WndProc(Message& m)
       at System.Windows.Forms.Form.WmShowWindow(Message& m)
       at System.Windows.Forms.Form.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.SafeNativeMethods.ShowWindow(HandleRef hWnd, Int32 nCmdShow)
       at System.Windows.Forms.Control.SetVisibleCore(Boolean value)
       at System.Windows.Forms.Form.SetVisibleCore(Boolean value)
       at System.Windows.Forms.Control.set_Visible(Boolean value)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at AppServicesClient.Program.Main() in C:\Users\drogers\Documents\Visual Studio 2008\Projects\AppServicesDemo\AppServicesClient\Program.cs:line 18
       at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

I found that by replacing the null arguments with string.empty, (Membership.ValidateUser(string.Empty, string.Empty)) the program worked as expected.

Thanks again and ciao,
David