findcontrol not working for dynamically generated HTMLselect

Question

I generate select control(Q1DDL and Q2DDL) in the innerHTML of a div divQ1AnswerDDLSub in the pageload

The code is perfectly generated as desired.

However, the findControl of ASP.net is not able to find the generated HTMLSELECT control (Q1DDL and Q2DDL)from the .aspx page after I press the SUBMIT Button.

The runtime HTMLSelect control generation

                protected void Page_Load(object sender, EventArgs e)
   {
    if (IsPostBack)
    {
        return;
    }   
....
if (bool.Parse(questions[QNo-1].AnswerDropDownList.visibleDDl))
            {
                (FindControl("lblQ" + QNo + "AnswerDDL") as HtmlGenericControl).InnerText = questions[QNo-1].AnswerDropDownList.titleDDL;
                (FindControl("fsQ" + QNo + "DDL") as HtmlGenericControl).Style["border"] = questions[QNo - 1].AnswerDropDownList.FieldsetDDL == "no" ? "0px" : null;
                var licDDL = questions[QNo-1].AnswerDropDownList.optionDDL;
                var builder = new System.Text.StringBuilder();
                for (int i = 0; i < licDDL.Length; i++)
                    {
                        builder.Append(String.Format("<option value='{0}' title='{1}'  >{1}</option> ", licDDL[i].value, licDDL[i].text));

                    }
                if (questions[QNo-1].AnswerDropDownList.required == "yes")
                    {
                        (FindControl("divQ" + QNo + "AnswerDDLSub") as HtmlGenericControl).InnerHtml = "<select runat=\"server\" name=\"Q" + QNo + "DDL\" id=\"Q" + QNo + "DDL\" required=\"required\">" + builder.ToString() + "</select>";
                    }
                else
                    {
                        (FindControl("divQ" + QNo + "AnswerDDLSub") as HtmlGenericControl).InnerHtml = "<select runat=\"server\" name=\"Q" + QNo + "DDL\" id=\"Q" + QNo + "DDL\">" + builder.ToString() + "</select>";
                    }
             }

The generated code when i view the page source

<div id="divQ1AnswerDDL">
            <fieldset id="fsQ1DDL" style="border:;">
                <legend>
                    <label id="lblQ1AnswerDDL">Title of Drop Down List </label>
                </legend>
                <div id="divQ1AnswerDDLSub"><select runat="server" name="Q1DDL" id="Q1DDL" required="required"><option value='' title='Select'  >Select</option> <option value='IE' title='IE'  >IE</option> <option value='Safari' title='Safari'  >Safari</option> <option value='Chrome' title='Chrome'  >Chrome</option> </select></div>
            </fieldset>
        </div>

in the code behind

protected void btnSubmit_Click(object sender, EventArgs e)
{     
....
for (int QNo = 1; QNo < questions.Length + 1; QNo++)
        {
          ADDLRequired = (FindControl("Q" + QNo + "DDL") as     HtmlSelect).Attributes["required"] == "required" ? true: false,


}
}

(FindControl("Q" + QNo + "DDL") as HtmlSelect) <== is showing null

Aristos Aristos · Accepted Answer · 2016-12-05T08:46:46

First of all lets start with the mistake that you render this

<select runat="server" name="Q1DDL" id="Q1DDL" required="required"><option

as string inside HTML page, and the mistake is that you expect that this will be compile. No actually this is not compile - the compile is happens before, after the compile this will be render as text - and not more compiles are happens.

So stick on this as first step... solve that, and then solve the rest issues.

Possible work out

Render what ever html normal control you like, with out the runat="server", then render it again after post back and get the post back using the Request.Form["ControlName"] to get the post back value

findcontrol not working for dynamically generated HTMLselect

1 Answers

Possible work out