Access a HTML InputBox through the Code-Page

bwalker · #1 (**permalink**) Nov 7th, 2005, 16:07

I have a HTML control Inputbox:
<INPUT type="text" onkeyup="chkText(tester.value)" id="tester">

I want to access it through my codepage when I press a button

PrivateSub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim strMessage As HtmlInputText
strMessage = Me.tester
Dim strScript AsString = "<script language=JavaScript>alert('" & strMessage.Value & "');</script>"
If (Not Page.IsStartupScriptRegistered("clientScript")) Then
Page.RegisterStartupScript("clientScript", strScript)
EndIf

EndSub

the error I get is:
Object reference not set to an instance of an object.

I want to keep the textbox client side validation because I check on every keyup. Is there any way to grab the text from the inputbox and use.

Thanks
Bob

#2 (**permalink**) Nov 8th, 2005, 00:20

You need to be using a server-side control to access it in server-side script. Try using

<asp:TextBox id="tester" runat="server"></asp:TextBox>

and access it's value in your click event as tester.text

and that needs to be within a <form id="form1" runat=server></form> element for .NET to treat it as a post-back.

u2orange · #3 (**permalink**) Nov 8th, 2005, 13:12

Look at this example I have put together for you, it should help you out. It might also be of use to some other areas of your asp.net coding.

htmlcontrol.aspx

Code: Select all

<%@ Page Language="VB" Inherits="Webforumz.ExposeHtmlControl" src="htmlcontrol.aspx.vb" ContentType="text/html" ResponseEncoding="iso-8859-1" %>
<html>
<head>
 <title>HTML Control</title>
 <script language="javascript" type="text/javascript">
  function jsValidate()
   {
   alert('Key pressed')
   }
 
  function jsAlert()
   {
   alert('You clicked submit')
   }
 </script>
</head>
<body>
<form runat="server">
 
 <input type="text" id="txt_htmlinput" runat="server" onKeyUp="jsValidate()" /><asp:Button id="btn_submit" runat="server" onclick="btn_submit__Click" Text="Submit" />
 
 <p><asp:Label id="lbl_message" runat="server" /></p>
</form>
</body>
</html>

htmlcontrol.aspx.vb

Code: Select all

Imports System
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.HtmlControls
Namespace Webforumz
Public Class ExposeHtmlControl
 Inherits Page
 
'=========================================================================================================================================================================================================== 
' Declarations
 Protected WithEvents txt_htmlinput As HtmlControl
 Protected WithEvents btn_submit As Button
 Protected WithEvents lbl_message As Label
 
'=========================================================================================================================================================================================================== 
' Page Events
 
 Sub Page_Load(sender As Object, e As EventArgs)
 
  If not IsPostback()
   ' Add JS event to 'btn_submit'
   btn_submit.Attributes.Add("onclick", "jsAlert()")
  End If
 End Sub
 
 
'=========================================================================================================================================================================================================== 
' Click Events
 Sub btn_submit__Click(s As Object, e as EventArgs)
  lbl_message.text = txt_htmlinput.Attributes("value")
 End Sub
'=========================================================================================================================================================================================================== 
End Class
End Namespace

Hope that helps

bwalker · #4 (**permalink**) Nov 9th, 2005, 11:43

Yes thanks, I could have sworn I tried it like that??

u2orange · #5 (**permalink**) Nov 10th, 2005, 12:34

Have you got is sussed yet?

bwalker · #6 (**permalink**) Nov 10th, 2005, 12:58

I think I see what my problem was. I was assuming that a web textbox was the same as a HTML textbox with "runat"=server. I now see that web textbox is stricly code-back page while HTML textbox can be seen in HTML script side and also code-back page.

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Access a HTML InputBox through the Code-Page