Question

I have a user control with some custom client side validation. When I have the user control on a page, it works no problem. But if that page has a postback event (select a certain option from a dropdown, and more fields are displayed), my validation no longer seems to work. My validation is as follows:

protected void Page_Load(object sender, EventArgs e)
{
    Type cstype = this.GetType();

    if (!Page.ClientScript.IsStartupScriptRegistered(cstype, "ValidatorType"))
    {
        String DateValidator;
        DateValidator = "<script type=\"text/javascript\">\n";
        DateValidator += "function ValidateDate(source, args) {\n";
        DateValidator += "   var ddDay = document.getElementById(source.day);\n";
        DateValidator += "   var day = ddDay.selectedIndex;";
        DateValidator += "   var ddMonth = document.getElementById(source.month);\n";
        DateValidator += "   var month = ddMonth.selectedIndex;\n";
        DateValidator += "   var ddYear = document.getElementById(source.year);\n";
        DateValidator += "   var year = ddYear.selectedIndex;\n";
        DateValidator += "   if (day == 0 || month == 0 || year == 0)\n";
        DateValidator += "      args.IsValid = false;\n";
        DateValidator += "   else\n";
        DateValidator += "      args.IsValid = true;\n";
        DateValidator += "   }\n";
        DateValidator += "</script>";
        Page.ClientScript.RegisterStartupScript(cstype, "ValidatorType", DateValidator);
    }
    Page.ClientScript.RegisterExpandoAttribute(reqDueDate.ClientID, "month", ddMonth.ClientID);
    Page.ClientScript.RegisterExpandoAttribute(reqDueDate.ClientID, "day", ddDay.ClientID);
    Page.ClientScript.RegisterExpandoAttribute(reqDueDate.ClientID, "year", ddYear.ClientID);
}

I’m stumped. Any advice?

EDIT:

Here is the User Control that I am using.

<asp:DropDownList ID="ddMonth" runat="server" AppendDataBoundItems="true">
   <asp:ListItem Value="">--Month--</asp:ListItem>
</asp:DropDownList>
<asp:DropDownList ID="ddDay" runat="server" AppendDataBoundItems="true">
    <asp:ListItem Value="">--Day--</asp:ListItem>
</asp:DropDownList>
<asp:DropDownList ID="ddYear" runat="server" AppendDataBoundItems="true">
    <asp:ListItem Value="">--Year--</asp:ListItem>
</asp:DropDownList>
<asp:CustomValidator ID="reqDueDate" EnableClientScript="true" ClientValidationFunction="ValidateDate" runat="server" ErrorMessage="Required" CssClass="input-notification error png_bg" Display="Dynamic"></asp:CustomValidator>

Answer 1

Turns out, I needed to do 2 things. Put an Update Panel around in my user code, and change the lines

Page.ClientScript.RegisterExpandoAttribute(reqDueDate.ClientID, "day", ddDay.ClientID);

to

ScriptManager.RegisterExpandoAttribute(UpdatePanelDDD, reqDueDate.ClientID, "day", ddDay.ClientID, false);

Thanks all for your help and http://www.aspnetajaxtutorials.com/2010/09/customvalidator-registerexpandoattribut.html for the guidance.