mcs/class/System.Web/System.Web.UI.WebControls/HiddenField.cs

   1 //
   2 // System.Web.UI.WebControls.HiddenField.cs
   3 //
   4 // Authors:
   5 //  Lluis Sanchez Gual (lluis@novell.com)
   6 //
   7 // (C) 2005-2010 Novell, Inc. (http://www.novell.com)
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 using System.Web.UI;
  32 using System.ComponentModel;
  33
  34 namespace System.Web.UI.WebControls
  35 {
  36         [DefaultEvent ("ValueChanged")]
  37         [DefaultProperty ("Value")]
  38         [Designer ("System.Web.UI.Design.WebControls.HiddenFieldDesigner, " + Consts.AssemblySystem_Design, "System.ComponentModel.Design.IDesigner")]
  39         [ControlValueProperty ("Value")]
  40         [NonVisualControl]
  41         [ParseChildren]
  42         [PersistChildren (false)]
  43         [SupportsEventValidation]
  44         public class HiddenField : Control, IPostBackDataHandler
  45         {
  46                 static readonly object ValueChangedEvent = new object ();
  47
  48                 public event EventHandler ValueChanged {
  49                         add { Events.AddHandler (ValueChangedEvent, value); }
  50                         remove { Events.RemoveHandler (ValueChangedEvent, value); }
  51                 }
  52
  53                 [DefaultValue ("")]
  54                 [Bindable (true)]
  55                 public virtual string Value {
  56                         get { return ViewState.GetString ("Value", String.Empty); }
  57                         set { ViewState ["Value"] = value; }
  58                 }
  59
  60                 [DefaultValue (false)]
  61                 [EditorBrowsable (EditorBrowsableState.Never)]
  62                 public override bool EnableTheming {
  63                         get { return false; }
  64                         set { throw new NotSupportedException (); }
  65                 }
  66
  67                 [DefaultValue ("")]
  68                 [EditorBrowsable (EditorBrowsableState.Never)]
  69                 public override string SkinID {
  70                         get { return String.Empty; }
  71                         set { throw new NotSupportedException (); }
  72                 }
  73
  74                 [EditorBrowsable (EditorBrowsableState.Never)]
  75                 public override void Focus ()
  76                 {
  77                         throw new NotSupportedException ();
  78                 }
  79
  80                 protected virtual void OnValueChanged (EventArgs e)
  81                 {
  82                         EventHandler h = (EventHandler) Events [ValueChangedEvent];
  83                         if (h != null)
  84                                 h (this, e);
  85                 }
  86
  87                 protected virtual bool LoadPostData (string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
  88                 {
  89                         if (Value != postCollection [postDataKey]) {
  90                                 Value = postCollection [postDataKey];
  91                                 return true;
  92                         }
  93                         return false;
  94                 }
  95
  96                 protected virtual void RaisePostDataChangedEvent ()
  97                 {
  98                         ValidateEvent (UniqueID, String.Empty);
  99                         OnValueChanged (EventArgs.Empty);
 100                 }
 101
 102                 protected override ControlCollection CreateControlCollection ()
 103                 {
 104                         return new System.Web.UI.EmptyControlCollection (this);
 105                 }
 106
 107                 protected internal override void OnPreRender (EventArgs e)
 108                 {
 109                         base.OnPreRender (e);
 110                 }
 111
 112                 protected internal override void Render (HtmlTextWriter writer)
 113                 {
 114                         Page page = Page;
 115                         string uniqueid = UniqueID;
 116                         if (page != null)
 117                                 page.ClientScript.RegisterForEventValidation (uniqueid);
 118
 119                         writer.AddAttribute (HtmlTextWriterAttribute.Type, "hidden", false);
 120
 121                         if (!String.IsNullOrEmpty (ClientID))
 122                                 writer.AddAttribute (HtmlTextWriterAttribute.Id, ClientID);
 123
 124                         if (!String.IsNullOrEmpty (uniqueid))
 125                                 writer.AddAttribute (HtmlTextWriterAttribute.Name, uniqueid);
 126
 127                         if (!String.IsNullOrEmpty (Value))
 128                                 writer.AddAttribute (HtmlTextWriterAttribute.Value, Value);
 129
 130                         writer.RenderBeginTag (HtmlTextWriterTag.Input);
 131                         writer.RenderEndTag ();
 132                 }
 133
 134                 #region IPostBackDataHandler Members
 135
 136                 bool IPostBackDataHandler.LoadPostData (string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
 137                 {
 138                         return LoadPostData (postDataKey, postCollection);
 139                 }
 140
 141                 void IPostBackDataHandler.RaisePostDataChangedEvent ()
 142                 {
 143                         RaisePostDataChangedEvent ();
 144                 }
 145
 146                 #endregion
 147         }
 148 }
 149