Hi Suresh,
Please try the following:
*** First my HTML
<HTML>
<HEAD>
<title>DropDownValid</title>
<meta name="GENERATOR" content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" content="Visual Basic .NET 7.1">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema"
content="http://schemas.microsoft.com/intellisense/ie5">
<script language="javascript">
<!--
function DropChange(eventTarget, eventArgument) {
if (typeof(Page_ClientValidate) == 'function')
{
Page_ClientValidate();
if (Page_IsValid)
__doPostBack(eventTarget,eventArgument);
return Page_IsValid;
}
else
{
__doPostBack(eventTarget,eventArgument);
return true;
}
}
//-->
</script>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<asp:TextBox id="TextBox1" runat="server"></asp:TextBox>
<asp:RequiredFieldValidator id="RequiredFieldValidator1" runat="server"
ErrorMessage="RequiredFieldValidator"
ControlToValidate="TextBox1"></asp:RequiredFieldValidator>
<asp:DropDownList id="DropDownList1" runat="server"></asp:DropDownList>
<asp:LinkButton id="LinkButton1" runat="server">test</asp:LinkButton>
</form>
</body>
</HTML>
*** My code-behind
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
If Not IsPostBack Then
DropDownList1.Items.Add("a")
DropDownList1.Items.Add("b")
DropDownList1.Items.Add("c")
DropDownList1.Attributes.Add("onchange", "return
DropChange('DropDownList1', '');")
End If
End Sub
Private Sub DropDownList1_SelectedIndexChanged(ByVal sender As Object,
ByVal e As System.EventArgs) Handles DropDownList1.SelectedIndexChanged
Response.Write("the index changed")
End Sub
*** How it works
- The link button causes validation & works normally.
- The drop list only posts if the page is valid.
- The code-behind DropDownList1_SelectedIndexChanged event correctly fires
because we pass the correct argument to __doPostBack.
- Notice that I set the drop list's AutoPostBack to false. That is because
AutoPostBack creates an onchange event for the drop list which might
interfere with our onchange event code. Further, our code includes the
functionality of the code that AutoPostBack would have added.
Thank you, Mike
Microsoft, ASP.NET Support Professional
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--------------------[color=blue]
> Content-Class: urn:content-classes:message
> From: "Suresh" <anonymous@discussions.microsoft.com>
> Sender: "Suresh" <anonymous@discussions.microsoft.com>
> References: <uBO2k9LwDHA.540@tk2msftngp13.phx.gbl>[/color]
<062101c3c0cf$c40b1610$a001280a@phx.gbl>[color=blue]
> Subject: re: AutoPostBack & Validation
> Date: Fri, 12 Dec 2003 09:33:02 -0800
> Lines: 47
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>
> I just tried this and it doesn't seem to work.
>[color=green]
> >-----Original Message-----
> >Try this..(NOTE: I've done this with ASP:Buttons but not
> >with drop down list but it should work the same way.)
> >
> >In the codebehind in your Page_Load function add the
> >client side javascript to the OnChange event of your drop
> >down list.
> >
> >myDropDownList.Attributes.Add("OnChange", "return
> >MyJavaScriptFunction();");
> >
> >In your MyJavaScriptFunction perform your validation and
> >return true if it passes or false if it fails.
> >If you return a false that should prevent the Postback on
> >the OnChange event of the drop down list.
> >
> >HTH,
> >Suresh.
> >[color=darkred]
> >>-----Original Message-----
> >>If I put RequiredFiledValidators on a page and set them[/color]
> >up with[color=darkred]
> >>corresponding TextBoxes everything works just fine. If[/color][/color]
> I[color=green]
> >add a DropDownList[color=darkred]
> >>and set its AutoPostBack to True, I am able to post data[/color]
> >to the server[color=darkred]
> >>WITHOUT the validators invoking their validation.
> >>
> >>It seems that the easiest solution would have been for[/color][/color]
> MS[color=green]
> >to simply give the[color=darkred]
> >>DropDownList control a "CausesValidation" property, but[/color]
> >it does not have[color=darkred]
> >>one.
> >>
> >>How can I invoke the client-side validations when a[/color]
> >DropDownList causes the[color=darkred]
> >>PostBack?
> >>
> >>
> >>.
> >>[/color]
> >.
> >[/color]
>[/color]
