Form Validation

arpan · Dec 20, 2002

A Web Form has 2 radio buttons (of the same group) & a ListBox. When the page loads for the 1st time, the 1st radio button is checked by default & the ListBox remains invisible. Only if the 2nd radio button is selected by a user, the ListBox becomes visible. I am hiding & unhiding the ListBox using JavaScript. Now I want to validate that if the 2nd radio button is selected, then at least one of the options in the ListBox should be selected by the user else show him an error message. How do I do this?

Thanks,

Arpan

Isadore · Dec 22, 2002

Arpan: I tried the "Required Field Validator" but I guess it doesn't recognize listboxes. Anyway, you could probably stick strickly with Java by attaching an attribute to the listbox, etc etc.. However, if you can tolerate a post back you could accomplish this by using a PostBack from radiobutton No. 2, e.g.,

In the code behind:

Sub chkB_CheckedChanged(Sender As Object, e As EventArgs)
If lstA.SelectedIndex = -1 Then 'no selection
lblreq.Text="You must make a listbox selection!"
Exit Sub
Else
Response.Redirect("mypage.aspx&quot

Exit Sub
End If
End Sub

and in the HTML you'd have...

<HTML>
<body>
<form id="Form1" runat="server">
<asp:Listbox id="lstA" runat="server" ..vis/invis Java here/><br>
<asp:radiobutton id="A" runat="server" GroupName="mygrp" Text="First Choice" Checked="True"/>
<asp:radiobutton id="B" runat="server" GroupName="mygrp" Text="Second Choice" AutoPostBack="True" OnCheckedChanged="chkB_CheckedChanged"/>
<br><asp:Label id="lblreq" runat="server" Font-Bold="True" ForeColor="Red"/>
</form>
</body>

...and you could toggle the visibility of the label in the code behind if necc.

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Form Validation

arpan

Programmer

Isadore

Technical User

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