Client Validation Function for Radio Buttons on a ASPX file - asp.net

Question

This is an ASPX/CS program with Javascript.
I have inherited this code and I am trying to complete the validation which was not completed. I have found the javascript code which validates of a radio button is clicked but the aspx code does not reference it.
Radio buttons are grouped together such that when one in the group is selected, the others are unselected. But, for starters, I cannot see how to utilize this. It must have something to do with the "GroupName" that each radio button mentions.
<ItemTemplate>
<%# FormatGroup(Eval("Group").ToString()) %>
<tr>
<td> <asp:Label ID="lblQuestion" runat="server" Text='<%# Eval("Question") %>'><%# Eval("Question") %></asp:Label></td>
<td align="center" width="10%"><asp:RadioButton ID="rblEvalQuestion4" runat="server" GroupName='<%# Eval("Question") %>' /></td>
<td align="center" width="10%"><asp:RadioButton ID="rblEvalQuestion3" runat="server" GroupName='<%# Eval("Question") %>' /></td>
<td align="center" width="10%"><asp:RadioButton ID="rblEvalQuestion2" runat="server" GroupName='<%# Eval("Question") %>' /></td>
<td align="center" width="10%"><asp:RadioButton ID="rblEvalQuestion1" runat="server" GroupName='<%# Eval("Question") %>' /></td>
</tr>
</ItemTemplate>
So how would I make use of the ClientValidationFunction method in asp for radio button groups?

Answer 1

Try a custom field validator.
Add this bit of JavaScript:
<script language="javascript" type="text/javascript" >
function ClientValidate(source,args)
{
if(document.getElementById("<%= rblEvalQuestion1.ClientID %>").checked || document.getElementById("<%= rblEvalQuestion2.ClientID %>").checked || document.getElementById("<%= rblEvalQuestion3.ClientID %>").checked || document.getElementById("<%= rblEvalQuestion4.ClientID %>").checked)
{
args.IsValid = true;
}
else
{
args.IsValid = false;
}
}
</script>
Add this validator to the page:
<asp:CustomValidator id="RadioButtonValidator" runat="server" Display="Dynamic" ErrorMessage="Please select an option." ClientValidationFunction="ClientValidate" OnServerValidate="ServerValidate"></asp:CustomValidator>
And this method in the code behind:
protected void ServerValidate(object source, ServerValidateEventArgs args)
{
args.IsValid = rblEvalQuestion1.Checked || rblEvalQuestion2.Checked || rblEvalQuestion3.Checked || rblEvalQuestion4.Checked;
}
Finally, make sure to check if
Page.IsValid
in your button for submitting the form.
Finally, if you can re-factor this into a RadioButtonList you can simply just use a RequiredFieldValidator which will make your life a lot easier to implement!