How to add a DropDownList programmatically in C#

Question

So I've got a masterpage on which a DropDownList should be displayed. Then I've got a class which should create a DropDownList. But since I've only got one page with a DDL I don't want to write inside the masterpage.aspx. So my question is if it is even possible to write all the code inside C# to create the DropDownList. Do I need someting like that?

<asp:Panel ID="pnlChannel" runat="server">

or can I just do it like that:

Panel pnlChannel = new Panel();

But if I do it in the codebehind It won't display anything

This is my code so far:

 public Panel GetDropDownList()
{
    // Create drop down list and data source
    Panel pnlChannel = new Panel();
    DropDownList ddlChannel = new DropDownList();
    ListItem limDefault = new ListItem();
    SqlDataSource sdsChannel = new SqlDataSource();

    // Configure data source
    sdsChannel.ConnectionString = ConfigurationManager.ConnectionStrings["SQL"].ConnectionString;
    sdsChannel.SelectCommand = "SELECT * FROM Kanal";
    sdsChannel.ID = "sdsChannel";

    // Configure drop down list
    ddlChannel.DataTextField = "Kanal";
    ddlChannel.DataValueField = "Kanal";
    ddlChannel.AppendDataBoundItems = true;
    ddlChannel.DataSourceID = "sdsChannel";



    // Configure default list item
    limDefault.Selected = true;
    limDefault.Text = "Alle";
    limDefault.Value = "-1";

    // Add controls to static panel in footer
    ddlChannel.Items.Add(limDefault);
    pnlChannel.Controls.Add(ddlChannel);
    pnlChannel.Controls.Add(sdsChannel);

    return pnlChannel;
}

I don't really know what I have to do, to display it on the page. If I debug it and execute the page, it calls the method but it still won't show up on the page

Answer 1

Html Markup:

Add a panel control on your .aspx page

<asp:Panel ID="Panel1" runat="server">
</asp:Panel>

Code-behind: on pageload

DropDownList ddl = new DropDownList();
ddl.DataSource = sdsChannel;
ddl.DataTextField = "Kanal";
ddl.DataValueField = "Kanal";
ddl.DataBind();
Panel1.Controls.Add(ddl);

---

Html Markup :

Added panel control on master page under form tag

<asp:Panel id="pnlMasterPage" runat="server">
</asp:Panel>

Method 1 : On masterpage on_load

DropDownList ddl = new DropDownList();
ddl.DataSource = sdsChannel;
ddl.DataTextField = "Kanal";
ddl.DataValueField = "Kanal";
ddl.DataBind();
pnlMasterPage.Controls.Add(ddl);

Method 2 : If you want to bind from child page then, on child page on_load

DropDownList ddl = new DropDownList();
ddl.DataSource = sdsChannel;
ddl.DataTextField = "Kanal";
ddl.DataValueField = "Kanal";
ddl.DataBind();
Panel pnl = this.Master.FindControl("pnlMasterPage") as Panel;
pnl.Controls.Add(ddl);

Answer 2

My experience is based on WinForms with C#, still it may be relevant.

As in your code, this could work:

Panel pnlChannel = GetDropDownList(); //returns a configured panel with controls.
pnlChannel.Location = new Point(56,72); //Should not be required
pnlChannel.Size = new Size(264, 152); //Should not be required
pnlChannel.Visible=true; //(Or sometimes Show(), depending).

Do you know if the panel has to be added somewhere? Sorry, my exp is based on WinForms, it's not required.