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Enable ReadOnly Mode for your WebForms!

, 24 Feb 2004
This article will show you, how to implement a readonly mode for webforms.
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;


namespace Trivadis.Spieler.ReadOnly {
	/// <summary>
	/// Summary description for BasePage.
	/// </summary>
	public class BasePage: System.Web.UI.Page {

		private DataTable _ControlContainer = null;
		private string _MultiDelimiter = ", ";

		public BasePage():base() {}

		/// <summary>
		/// Set the passed Controls in a read-only mode
		/// </summary>
		/// <param name="cc"></param>
		public void SetReadOnly(ControlCollection cc) {
			CreateDataTable();
			CollectControls(cc);
			ReplaceControls();
		}
		
	
		/// <summary>
		/// Create ControlContainer on the fly
		/// (better should be a typed Table / typed object)
		/// </summary>
		/// <returns></returns>
		private DataTable CreateDataTable() {
			
			_ControlContainer = new DataTable("TextBoxes");
			DataColumn dcControlColl = new DataColumn("ControlCollection", typeof(System.Object));
			DataColumn dcControl = new DataColumn("Control", typeof(System.Object));
			DataColumn dcIndex = new DataColumn("Index", typeof(System.Int32));
			_ControlContainer.Columns.Add(dcControlColl);
			_ControlContainer.Columns.Add(dcControl);
			_ControlContainer.Columns.Add(dcIndex);

			return _ControlContainer;
		}


		/// <summary>
		/// Replace writable controls with read-only controls
		/// </summary>
		private void ReplaceControls() {

			//Change sort-order, because removing should start from the highest index
			DataRow[] drs = _ControlContainer.Select("", "Index desc");

			foreach(DataRow dr in drs) {

				ControlCollection cc = (ControlCollection)dr["ControlCollection"];
				Control c = (Control)dr["Control"];
				int index = cc.IndexOf(c);

				//Remove existing Control
				cc.RemoveAt(index);

				Label l = new Label();
				l.CssClass = "lbl";

				//WebControl and HtmlControl don't have an equal Base Class (!)
				if (c is WebControl)
				{
					l.Style.Add("LEFT", ((WebControl)c).Style["LEFT"]);
					l.Style.Add("TOP", ((WebControl)c).Style["TOP"]);
					l.Style.Add("POSITION", ((WebControl)c).Style["POSITION"]);
					l.Style.Add("Z-INDEX", ((WebControl)c).Style["Z-INDEX"]);
				}
				else if (c is HtmlControl)
				{
					l.Style.Add("LEFT", ((HtmlControl)c).Style["LEFT"]);
					l.Style.Add("TOP", ((HtmlControl)c).Style["TOP"]);
					l.Style.Add("POSITION", ((HtmlControl)c).Style["POSITION"]);
					l.Style.Add("Z-INDEX", ((HtmlControl)c).Style["Z-INDEX"]);
				}

				if (c is TextBox) {
					l.Text = ((TextBox)c).Text;
				}
				else if (c is DropDownList || c is RadioButtonList) {
					if (((ListControl)c).SelectedValue != string.Empty)
						l.Text = ((ListControl)c).Items.FindByValue(((ListControl)c).SelectedValue).Text;
				}
				else if (c is CheckBoxList || c is ListBox) {
					if (((ListBox)c).SelectionMode == ListSelectionMode.Multiple) {
						foreach(ListItem li in ((ListBox)c).Items) {
							if (li.Selected) l.Text += li.Text + _MultiDelimiter;
						}
						if (l.Text.Length > 0)
							l.Text = l.Text.Substring(0, l.Text.LastIndexOf(_MultiDelimiter));
					}
					else {
						l.Text = ((ListBox)c).SelectedValue;
					}
				}
				else if (c is RadioButton || c is CheckBox) {
					l.Text = ((CheckBox)c).Checked.ToString();				
				}
				else {
					//Validators and Buttons does not exist in readonly mode
					if (!(c is BaseValidator) && !(c is Button))
					{
						//unknown type
						throw new ArgumentOutOfRangeException("Controltype not supported at the moment", c.ToString());
					}
				}

				//Add new read-only Control
				cc.AddAt(index, l);

			}

		}

		
		/// <summary>
		/// Check all controls inside Collection and put them into a ControlContainer
		/// </summary>
		/// <param name="cc">ControlCollection</param>
		private void CollectControls(ControlCollection cc) {
			
			foreach(Control c in cc) {
			
				//Which Controls do we support?
				if (c is TextBox || 
					c is ListBox || 
					c is DropDownList || 
					c is RadioButton ||
					c is RadioButtonList ||
					c is CheckBox ||
					c is CheckBoxList ||
					c is BaseValidator ||
					c is Button)
					_ControlContainer.Rows.Add(new object[]{cc, c, cc.IndexOf(c)});
				
				//Are there further Controls inside current Control?
				if (c.HasControls())	
					CollectControls(c.Controls);
			}		
				
		}
		
	}

}

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About the Author

Patrick Spieler
Web Developer
Switzerland Switzerland
Consultant for Trivadis AG in Switzerland.
Interested in .NET, Architectures, Patterns and Web 2.0.
Blog and articles at http://sharpcuts.blogspot.com

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Article Copyright 2004 by Patrick Spieler
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