Question

I am using Telerik ASP.Net Ajax controls (theoretically shouldn’t matter who makes the 3rd party control). I would like to create my own custom server control (not user control) that has my own predefined HTML output but also includes a Telerik DatePicker. Since the Telerik DatePicker is another server control what is the correct procedure to place a server control into my custom server control.

My understanding is that server controls work by writing html output. How can I write the output of another control that I instantiate in the Render method and still retain the original controls individual lifecycle.

Desired outcome:

• My own custom server control that contains many 3rd party controls (ie. RadDatePicker).

Solution

Thanks to @Sumo for pointing me into the direction of the Composite control. Documentation is available here.

I was able to solve the issue by creating a control that inherits CompositeDataBoundControl. Then databinding my datasource, calculating how many custom controls needed, placing them into an ArrayList and instantiating them correctly (with their own lifecycle in CreateChildControls()). I was then able to render each control in the ArrayList of DatePicker in the Render() method by invoking the ArrayList index that has not been rendered yet.
Eg. ((RadDatePicker)datePickerArray(instantiatedDatePickersCount)).RenderControl(writer).

Its a dirty solution at the moment but It works for my testing purposes.

Answer 1

You’ll want to create a CompositeControl. This allows you to easily add HTML markup and controls using an override of CreateChildControls and not have to think about too much else.

Some sample code:

using System.ComponentModel;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;

namespace TestServerControls {
    [DefaultProperty("Text")]
    [ToolboxData("<{0}:GridWithHeader runat=server></{0}:GridWithHeader>")]
    public class GridWithHeader : CompositeControl {
        private readonly GridView _grid = new GridView();
        private readonly HtmlGenericControl _header = new HtmlGenericControl("h1");

        public string Text {
            get { return _header.InnerHtml; }
            set { _header.InnerHtml = value; }
        }

        protected override void CreateChildControls() {
            Controls.Add(_header);
            Controls.Add(_grid);
        }
    }
}