A Better way? Finding ASP.NET controls, finding their id

Question

I have a method that finds all the controls, iterates through them, determines if they are a textbox,drop down list, etc.. retrieves their ID name, and depending on the ID name it will set a boolean statement (thus I would know if that section of the form is complete, and will email to a certain group of people) unfortunetly this is done with too many if statements and was wondering if I could get some help making this more manageable

protected void getEmailGroup()
{
    Control[] allControls = FlattenHierachy(Page);
    foreach (Control control in allControls)
    {
        if (control.ID != null)
        {
            if (control is TextBox)
            {
                TextBox txt = control as TextBox;
                if (txt.Text != "")
                {
                    if (control.ID.StartsWith("GenInfo_"))
                    {
                        GenInfo = true;
                    }
                    if (control.ID.StartsWith("EmpInfo_"))
                    {
                        EmpInfo = true;
                    }
                }
            }
            if (control is DropDownList)
            {
                DropDownList lb = control as DropDownList;
                if (lb.SelectedIndex != -1)
                {
                    if (control.ID.StartsWith("GenInfo_"))
                    {
                        GenInfo = true;
                    }
                    if (control.ID.StartsWith("EmpInfo_"))
                    {
                        EmpInfo = true;
                    }
                }
            }
        }
    }
}      

Answer 1

Why not just use the Control.FindControl(string) method?

private void Button1_Click(object sender, EventArgs MyEventArgs)
{
      // Find control on page.
      Control myControl1 = FindControl("TextBox2");
      if(myControl1!=null)
      {
         // Get control's parent.
         Control myControl2 = myControl1.Parent;
         Response.Write("Parent of the text box is : " + myControl2.ID);
      }
      else
      {
         Response.Write("Control not found");
      }
}

from: https://learn.microsoft.com/en-us/dotnet/api/system.web.ui.control.findcontrol

Answer 2

It is hard to understand the logic behind your code, but I'm sure it can be written easier. For example you can do something like this:

DropDownBox box = FlattenHierachy(Page)
   .Where(c => c is DropDownList)
   .Cast<DropDownList>()
   .Where(d => d.SelectedIndex != -1)
   .FirstOrDefault();
if (box != null)
{
   if (box.ID.StartsWith("GenInfo_"))
   {
      GenInfo = true;
   }
   if (box.ID.StartsWith("EmpInfo_"))
   {
       EmpInfo = true;
   }
}

Obviously you can make this generic if you extract the lambda expression from the seconde Where call. So you could reuse it for different types. That's the solution which is as close to your code as possible, but I guess it would be a better idea to use a recursive method traversing the page and giving that method your predicates as lambda expressions.