ASP.Net Server Control

Priti Kumari
Feb 23, 2014
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In this article I will use a TextBox Control for examples.

How to create ASP.NET server control
How to use an ASP.NET server control in a webpage (.aspx)

How to create ASP.NET server control

Step 1 : Go to Visual Studio 2010 and select "File" -> "New" -> "Project...".

Step 2 : Go to "Web" -> "ASP.NET Server Control" -> "Ok".

Step 3 : After adding a Server Control go to the code file and inherit a TextBox Control class.

You can inherit any other control (TextBox, Dropdownlist or CheckBoxList) that you want to create.

Step 4 : Then override the property of the control and write your own customized code in it.

using System.Linq;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Drawing;

namespace MyServerControl
{
  [DefaultProperty("Text")]
  [ToolboxData("<{0}:TextBoxMobile runat=server </{0}:TextBoxMobile>")]
  public class TextBoxMobile : TextBox
  {
  /// <summary>
  /// Here Override Text property of Textbox control.
  /// </summary>
  public override string Text
  {
  get
  {
            return ((base.Text == null) ?
                string.Empty : base.Text);
  }
  set
  {
  if (this.Page.IsPostBack)
  {
  base.Text = value;
  //Here you can write for validate control at server side.
  if (this.Text == string.Empty) this.BackColor = Color.Yellow;
  }

            }
  }

  /// <summary>
  /// Here Override Width property of textbox control.
  /// </summary>
  public override Unit Width
  {
  get
  {
  return 200;
  }}

  /// <summary>
  /// Here Override MaxLength Property of TextBox Control.
/// </summary>
  public sealed override int MaxLength
  {
  get
  {
  return 10;
  }
}
/// <summary>
  /// This Method Render html tag.
  /// </summary>
  /// <param name="output"></param>

  protected override void RenderContents(HtmlTextWriter output)
  {
  output.Write(Text);
  }
  /// <summary>
  /// In this method write code for <asp:TextBox ></TextBox> tag
  /// which attribute you want to add in html tag.
  /// </summary>
  /// <param name="writer"></param>
  protected override void AddAttributesToRender(HtmlTextWriter writer)
  {
  writer.AddAttribute("onkeypress", "return ValidateTextBox(event,this,
                                 'Mobile','" + MaxLength + "');");
            writer.AddStyleAttribute(HtmlTextWriterStyle.Width, this.Width.ToString());
  if (Text == String.Empty)
  {
  Text = (String)base.ViewState["Text"];
  }
  writer.AddAttribute("Text", Text);
  base.AddAttributesToRender(writer);
  }
  /// <summary>
  /// on this event you have to attached your Javascript file
  /// and css file to the paricular control.
  /// </summary>
  /// <param name="e"></param>
  protected override void OnInit(EventArgs e)
  {
  base.OnInit(e);
  if(this.Page.ClientScript.IsClientScriptIncludeRegistered(
            ControlScript"))
  return;
         this.Page.ClientScript.RegisterClientScriptInclude("ControlScript",
            this.Page.ClientScript.GetWebResourceUrl(this.GetType(),
  "MyServerControl.ClientSideValidation.js"));
  }
  }
}

How to use an ASP.NET Server Control in a web page (.aspx)

Step 1: Go to the ToolBox and add a Tab.

Step 2 : Here I need to add a tab and right-click on your own tab and then select the option: "Choose Items...".

Step 3 : Here I need to browse to the DLL of the Server Control that I need to create.

Step 4 : Here select the DLL file and click "Open".

Step 5 : Then we can see our own control; here then click "OK".

Step 6 : Then this control is added to the tab that I need to create.

Step 7 : Then drag and drop the control to multiple web pages and use it. After dragging the control onto a page the control is registered on the page automatically.