Вы можете использовать CustomValidator для проверки ввода в коде на стороне клиента или на стороне сервера.
разметка aspx
<asp:CheckBox ID="CheckBox1" runat="server" />
<asp:CheckBox ID="CheckBox2" runat="server" />
<asp:CheckBox ID="CheckBox3" runat="server" />
<asp:CheckBox ID="CheckBox4" runat="server" />
<asp:CustomValidator
ID="CustomValidator1"
runat="server"
ErrorMessage="put here error description"
ClientValidationFunction="clientfunc"
OnServerValidate="CheckValidate">
</asp:CustomValidator>
<asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
.cs (code-behind)
protected void CheckValidate(object source, ServerValidateEventArgs args)
{
args.IsValid=false;
if (CheckBox1.Checked)
args.IsValid = true;
if (CheckBox2.Checked)
args.IsValid = true;
if (CheckBox3.Checked)
args.IsValid = true;
if (CheckBox4.Checked)
args.IsValid = true;
}
protected void Button1_Click(object sender, EventArgs e)
{
if (IsValid)
{
//valid
}
else
{
//Invalid
}
}
код JavaScript
<script type="text/javascript">
function clientfunc(sender, args) {
args.IsValid = false;
if (document.getElementById("CheckBox1").checked)
args.IsValid = true;
if (document.getElementById("CheckBox2").checked)
args.IsValid = true;
if (document.getElementById("CheckBox3").checked)
args.IsValid = true;
if (document.getElementById("CheckBox4").checked)
args.IsValid = true;
}
</script>