在页面中找不到Checkbox控件

Question

I am trying to take the Checkboxes on the page and insert their Text into the database. When I click the submit button it doesn't find any of the Checkbox controls. I am trying to enumerate through all of them and insert each. I need to use individual checkboxes rather than a checkboxlist for this project in case someones suggests I use a list. Why aren't my controls showing up?

C# - Submit button

protected void Submit_Click(object sender, EventArgs e)
{
// removed code to shorten up
  foreach (Control c in Page.Controls)
  {
    foreach (Control childc in c.Controls)
    {
      if ((childc is CheckBox) && ((CheckBox)childc).Checked)
      {
         cmd.Parameters.Clear();
         cmd.Parameters.AddWithValue("@Name", ((CheckBox)childc).Text);
         cmd.Parameters.AddWithValue("@DateAdded", DateTime.Now.ToString());
         cmd.ExecuteNonQuery();
       }
    }
  }
}

C# - Where checkboxes are created and inserted into panel. I hit a button called Submit_Click_Generate which calls this and populates/creates the checkboxes.

protected void Submit_Click_Generate(object sender, EventArgs e)
{
// removed code to shorten up
  foreach (System.Xml.XmlNode node in nodes)
  {
     string displayname = node.SelectSingleNode("FName").InnerText.Trim();
     string idnumber = node.SelectSingleNode("idNum").InnerText.Trim();
     CheckBox ckBox = new CheckBox();
     ckBox.InputAttributes.Add("value", idnumber);
     panel1.Controls.Add(new LiteralControl("<div class='checkbox checkbox-slider-lg checkbox-slider--b-flat'><label>"));
     panel1.Controls.Add(ckBox);
     panel1.Controls.Add(new LiteralControl("<span>" + displayname + "</span></label></div>"));
    }
}

All of my checkboxes are dynamically inserted into this panel on my page

.ASPX

<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
   <form id="form1" runat="server">
       <asp:Button ID="btn" runat="server" OnClick="Submit_Click_Generate" Text="Generate" />
       <asp:Panel ID="panel1" runat="server"></asp:Panel>
       <asp:Button ID="btn1" runat="server" OnClick="Submit_Click" Text="Save" />
   </form>
</asp:Content>

Also tried this but it didn't pick up the controls either:

foreach (var ctrl in this.Controls.OfType<CheckBox>().Where(x => x.Checked))

Answer 1

Use...

 foreach (Control childc in panel1.Controls)
  {
    if ((childc is CheckBox) && ((CheckBox)childc).Checked)
    {
       cmd.Parameters.Clear();
       cmd.Parameters.AddWithValue("@Name", ((CheckBox)childc).Text);
       cmd.Parameters.AddWithValue("@DateAdded", DateTime.Now.ToString());
       cmd.ExecuteNonQuery();
     }
  }

Answer 2

For dynamically generated controls you need to recreate then in onInit event of the page when you click on submit button.according to the follownig link: Why dynamically created user controls disappear when controls are not doing full postbacks

You need to populate them on each Page Init event in order to persist Viewstate, also events for controls added inside an update panel during button clicks do not seems to get registered until the next Postback. My suggestion is to keep a list of what you have added dynamically, and store it in a session variable