Question

I have a page where I create div controls dynamiclly and number them automaticlly.

subCell = new TableCell();
subCell.Controls.Add(new LiteralControl(
    "<div id=\"picker" + Index.ToString() + "\" runat=\"server\" 
     class=\"colorSelector\"><div style=\"background-color: #000000;\">Text
     </div></div>"));
subRow.Cells.Add(subCell);
subTb.Rows.Add(subRow);

Later in the code I want to get the background-color value like so:

HtmlGenericControl div;

div = (HtmlGenericControl)Page.FindControl("picker" + e.CommandArgument.ToString());

string colorCode = div.Style["background-color"].ToString();

after these line of code I get a null object ref error.
div is null.
I have tried HtmlControl and LiteralControl as the object type and that does not help either.

Thank you!

Answer 1

Page.FindControl only works for server controls. You are assigning an id to text within the literal control which happens to be a div, but not the control itself. If you set the id of the control you should be able to find it, but I don’t know if that’s what you’re intending.

In response to your comment, check your HTML. The runat=server will probably be there because ASP.NET isn’t processing it as a control, it is treating it as content. Try something like this, noting that Page.FindControl only works on immediate children. Here I’ve declared a server panel named ‘declaredPanel’ in the aspx. ClientIdMode.Static makes it so ASP.NET won’t add parent names to the control (like “MainContent_childPanel”)

<asp:Panel ID="declaredPanel" runat="server" ClientIDMode="Static" />

In Page_Load:

    Panel p = new Panel();
    p.Style["background-color"] = "#aaeeaa";
    p.ID = "childPanel";
    p.ClientIDMode = System.Web.UI.ClientIDMode.Static;
    p.Controls.Add(new LiteralControl("<div id=\"div111\" runat=\"server\">Hello, world!</div>"));
    declaredPanel.Controls.Add(p);
    Panel p2 = declaredPanel.FindControl("childPanel") as Panel;
    string colorCode = p2.Style["background-color"]; // reports "#aaeeaa"

Produces this:

<div id="declaredPanel">
    <div id="childPanel" style="background-color:#aaeeaa;">
        <div id="div111" runat="server">Hello, world!</div>
    </div>
</div>