GetElementbyID" Exception unhandled" [英] GetElementbyID "Exception unhandled"

问题描述

大家好。

我正在为论坛制作登录应用程序，我的表单的目的是直接从应用程序登录论坛而不使用webbrowser。

我在表单中添加了一个隐藏的webbrowser，一个标签和2个文本框，用作用户名框，密码字段和"登录"按钮。

这些对象与具有以下scirpt的页面交互

WebBrowser1.Document.GetElementById（userbox）.InnerText = username

WebBrowser1.Document.GetElementById （keybox）.InnerText =密码

WebBrowser1.Document.GetElementById（loginbtn）.InvokeMember（" click"）

哪个不会导致Visual错误Studio，但是当我点击Label登录时，我得到一个"Exception unhandled"在我的脚本表中弹出。

它说

" System.NullReferenceException：'对象引用未设置为对象的实例。'



System.Windows.Forms.HtmlDocument.GetElementById（...）返回Nothing。"

异常详情：

System.NullReferenceException发生

  HResult = 0x80004003

  Message =对象引用未设置为对象的实例。

 来源= Epepistheway

  StackTrace：

   在Epepistheway.Form1.Label5_Click（对象发件人，EventArgs e）在C：\ Users \User \ AppData \ Local \ Temporary Projects \ Epepistheway \Form1.vb：第17行

   在System.Windows.Forms.Control.OnClick（EventArgs e）

   在System.Windows.Forms.Control.WmMouseUp（消息& m，MouseButtons按钮，Int32点击）

    at System.Windows.Forms.Control.WndProc（Message& m）

    at System.Windows.Forms.Label.WndProc（Message& m）

    at System.Windows.Forms.Control.ControlNativeWindow.OnMessage（Message& m）

    at System.Windows.Forms.Control.ControlNativeWindow.WndProc（Message& m）

   在System.Windows.Forms.NativeWindow.DebuggableCallback（IntPtr hWnd，Int32 msg，IntPtr wparam，IntPtr lparam）

    at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW（MSG& msg）

    at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop（IntPtr dwComponentID，Int32 reason，Int32 pvLoopData）

  ;   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner（Int32 reason，ApplicationContext context）

    at System.Windows.Forms.Application.ThreadContext.RunMessageLoop（Int32 reason，ApplicationContext context）

    at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun（）

    at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel（）

    at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run（String [] commandLine）

   在Epepistheway.My.MyApplication.Main（String [] Args）in：第81行

我如何修复这个？请帮忙。谢谢你的建议。

解决方案

嗨朋友，

这个问题与Winform有关，我将把它移到相应的论坛，以便您快速得到答案。

祝你好运，

陈伟伟

Hello everyone.

I am making a login App for my forum, the purpose of my form is to login to the forum directly from the app without use of webbrowser.

I added an hidden webbrowser in the form, a label and 2 text boxed, which works as Username Box, Password Field and ''login'' button.

Those objects interact with the page with the following scirpt

WebBrowser1.Document.GetElementById(userbox).InnerText = username
WebBrowser1.Document.GetElementById(keybox).InnerText = password
WebBrowser1.Document.GetElementById(loginbtn).InvokeMember("click")

Which doesn't result wrong to Visual Studio, but when I click the Label to login, I get a "Exception unhandled" popup in my script table.

It says

"System.NullReferenceException: 'Object reference not set to an instance of an object.'

System.Windows.Forms.HtmlDocument.GetElementById(...) returned Nothing."

Exception details:

System.NullReferenceException occurred
  HResult=0x80004003
  Message=Object reference not set to an instance of an object.
  Source=Epepistheway
  StackTrace:
   at Epepistheway.Form1.Label5_Click(Object sender, EventArgs e) in C:\Users\User\AppData\Local\Temporary Projects\Epepistheway\Form1.vb:line 17
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Label.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.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
   at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
   at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
   at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()
   at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()
   at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)
   at Epepistheway.My.MyApplication.Main(String[] Args) in :line 81

How do I fix this? Please help. Thanks in advice.

解决方案

Hi friend,

This issue is more related to Winform, I'll move it to corresponding forum for you to get a quick answer.

Best regards,

Fletch

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