ASP.NET

<.authentication mode="Forms"><br />
  <.forms loginUrl="login.aspx"><./forms><br />
 <./authentication><br />
  <.membership defaultProvider="SqlProvider"><br />
  <.providers><br />
   <.add name="SqlProvider" (then my sql connection string) /><br />
  <./providers>

public partial class _Default : System.Web.UI.Page
    {
        private ParentWebControl parentControl;
        private Button btnGetValues;
        protected void Page_Load(object sender, EventArgs e)
        {    }

        protected override void OnInit(EventArgs e)
        {
            base.OnInit(e);
            HtmlForm form = (HtmlForm)Page.FindControl("form1");
            btnGetValues = new Button();
            btnGetValues.Text = "Get values (aspx)";
            parentControl = new ParentWebControl();

            btnGetValues.ID = "btnGetValues";
            parentControl.ID = "parentCompositeControl";
            btnGetValues.Click += btnGetValues_Click;

            form.Controls.Add(btnGetValues);
            form.Controls.Add(parentControl);
        }

        void btnGetValues_Click(object sender, EventArgs args)
        {
            List <ChildControl> subChildren = parentControl.ChildControlList; 

        // this is always emtpy  !!!!     
            foreach (ChildControl child in subChildren)
            {
                string value1 = child.TextBox1.Text;
                string value2 = child.TextBox2.Text;
            }
        }
    }

 

PARENT CONTROL:

 public class ParentWebControl : CompositeControl
    {
        private Button addChildControl;
        private Label label;
        private List<ChildControl> childControlList;

        public ParentWebControl()
        {
            if(childControlList==null)
             childControlList = new List<ChildControl>();
        }

        public List<ChildControl> ChildControlList
        {
            get
            {
                EnsureChildControls();
                return childControlList;
            }
            set
            {
                EnsureChildControls();
                childControlList = value;
            }
        }

        private void  addChildControl_Click(object source, EventArgs e)
        {
            ChildControl newChild = new ChildControl();
            newChild.ID = "newChild";
            childControlList.Add(newChild);
        }

        protected override void OnInit(EventArgs e)
        {

            addChildControl = new Button();
            addChildControl.ID = "addChildControl";
            addChildControl.Click += addChildControl_Click;

            addChildControl.Text = "Add Child Control";

            label = new Label();
            label.ID = "myLabel";
            label.Text = "some label";

            Controls.Add(addChildControl);
            int id = 0;
            foreach (ChildControl control in ChildControlList)
            {
                control.ID = "childMemberControl" + id++;
                Controls.Add(control);
            }
            Controls.Add(label);
            base.OnInit(e);
        }       


        protected override void Render(HtmlTextWriter writer)
        {
            writer.RenderBeginTag(HtmlTextWriterTag.Div);
            addChildControl.RenderControl(writer);
            foreach (ChildControl control in ChildControlList)
            {
                control.RenderControl(writer);
            }
            label.RenderControl(writer);
            writer.RenderEndTag();
        }
    }

 

CHILDCONTROL:

public class ChildControl : WebControl
    {
        private TextBox textBox1;
        private TextBox textbox2;       

        public TextBox TextBox1
        {
            get
            {
                EnsureChildControls();
                return textBox1;
            }
            set
            {
                EnsureChildControls();
                textBox1 = value;
            }
        }

        public TextBox TextBox2
        {
            get
            {
                EnsureChildControls();
                return textbox2;
            }
            set
            {
                EnsureChildControls();
                textbox2 = value;
            }
        }

        public ChildControl()
        {
            TextBox1 = new TextBox();
            TextBox2 = new TextBox();
        }

        protected override void OnInit(EventArgs e)
        {
           
            TextBox1 = new TextBox();
            TextBox1.ID = "textBox1";
            TextBox2 = new TextBox();
             TextBox2.ID = "textBox2";
            Controls.Add(TextBox1);
            Controls.Add(TextBox2);
            base.OnInit(e);
        }

        protected override void Render(HtmlTextWriter writer)
        {
            writer.RenderBeginTag(HtmlTextWriterTag.Div);
            TextBox1.RenderControl(writer);
            TextBox2.RenderControl(writer);
            writer.RenderEndTag();
        }
    }