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

   1 //
   2 // System.Web.UI.WebControls.BaseDataBoundControl.cs
   3 //
   4 // Authors:
   5 //      Lluis Sanchez Gual (lluis@novell.com)
   6 //
   7 // Copyright (C) 2004-2005 Novell, Inc (http://www.novell.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 #if NET_2_0
  30 using System.Collections;
  31 using System.ComponentModel;
  32 using System.Security.Permissions;
  33
  34 namespace System.Web.UI.WebControls {
  35
  36         // CAS
  37         [AspNetHostingPermission (SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
  38         [AspNetHostingPermission (SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)]
  39         // attributes
  40         [DefaultProperty ("DataSourceID")]
  41         [DesignerAttribute ("System.Web.UI.Design.WebControls.BaseDataBoundControlDesigner, " + Consts.AssemblySystem_Design, "System.ComponentModel.Design.IDesigner")]
  42         public abstract class BaseDataBoundControl: WebControl
  43         {
  44                 static readonly object dataBoundEvent = new object ();
  45
  46                 EventHandlerList events = new EventHandlerList ();
  47
  48                 public event EventHandler DataBound {
  49                         add { events.AddHandler (dataBoundEvent, value); }
  50                         remove { events.RemoveHandler (dataBoundEvent, value); }
  51                 }
  52
  53                 object dataSource;
  54                 bool initialized;
  55                 bool preRendered;
  56                 bool requiresDataBinding;
  57
  58                 protected BaseDataBoundControl ()
  59                 {
  60                 }
  61
  62                 /* Used for controls that used to inherit from
  63                  * WebControl, so the tag can propagate upwards
  64                  */
  65                 internal BaseDataBoundControl (HtmlTextWriterTag tag) : base (tag)
  66                 {
  67                 }
  68
  69                 [BindableAttribute (true)]
  70                 [ThemeableAttribute (false)]
  71                 [DefaultValueAttribute (null)]
  72                 [DesignerSerializationVisibilityAttribute (DesignerSerializationVisibility.Hidden)]
  73                 public virtual object DataSource {
  74                         get {
  75                                 return dataSource;
  76                         }
  77                         set {
  78                                 if(value!=null)
  79                                         ValidateDataSource (value);
  80                                 dataSource = value;
  81                                 OnDataPropertyChanged ();
  82                         }
  83                 }
  84
  85                 [DefaultValueAttribute ("")]
  86                 [ThemeableAttribute (false)]
  87                 public virtual string DataSourceID {
  88                         get {
  89                                 return ViewState.GetString ("DataSourceID", "");
  90                         }
  91                         set {
  92                                 ViewState["DataSourceID"] = value;
  93                                 OnDataPropertyChanged ();
  94                         }
  95                 }
  96
  97                 protected bool Initialized {
  98                         get { return initialized; }
  99                 }
 100
 101                 protected bool IsBoundUsingDataSourceID {
 102                         get { return DataSourceID.Length > 0; }
 103                 }
 104
 105                 protected bool RequiresDataBinding {
 106                         get { return requiresDataBinding; }
 107                         set {
 108                                 // MSDN: If you set the RequiresDataBinding
 109                                 // property to true when the data-bound control
 110                                 // has already begun to render its output to the
 111                                 // page, the current HTTP request is not a
 112                                 // callback, and you are using the DataSourceID
 113                                 // property to identify the data source control
 114                                 // to bind to, the DataBind method is called
 115                                 // immediately. In this case, the
 116                                 // RequiresDataBinding property is _not_ actually
 117                                 // set to true.
 118                                 //
 119                                 // LAMESPEC, the docs quoted above mention that
 120                                 // DataBind is called in the described
 121                                 // case. This is wrong since that way we don't
 122                                 // break recursion when the property is set from
 123                                 // within the OnSelect handler in user's
 124                                 // code. EnsureDataBound makes sure that no
 125                                 // recursive binding is performed. Also the
 126                                 // property DOES get set in this case (according
 127                                 // to tests)
 128                                 if (value && preRendered && IsBoundUsingDataSourceID && Page != null && !Page.IsCallback) {
 129                                         requiresDataBinding = true;
 130                                         EnsureDataBound ();
 131                                 } else
 132                                         requiresDataBinding = value;
 133                         }
 134                 }
 135
 136                 protected void ConfirmInitState ()
 137                 {
 138                         initialized = true;
 139                 }
 140
 141                 public override void DataBind ()
 142                 {
 143                         PerformSelect ();
 144                 }
 145
 146                 protected virtual void EnsureDataBound ()
 147                 {
 148                         if (RequiresDataBinding && IsBoundUsingDataSourceID)
 149                                 DataBind ();
 150                 }
 151
 152                 protected virtual void OnDataBound (EventArgs e)
 153                 {
 154                         EventHandler eh = events [dataBoundEvent] as EventHandler;
 155                         if (eh != null)
 156                                 eh (this, e);
 157                 }
 158
 159                 protected virtual void OnDataPropertyChanged ()
 160                 {
 161                         if (Initialized)
 162                                 RequiresDataBinding = true;
 163                 }
 164
 165                 protected internal override void OnInit (EventArgs e)
 166                 {
 167                         base.OnInit (e);
 168                         Page.PreLoad += new EventHandler (OnPagePreLoad);
 169
 170                         if (!IsViewStateEnabled && Page != null && Page.IsPostBack)
 171                                 RequiresDataBinding = true;
 172                 }
 173
 174                 protected virtual void OnPagePreLoad (object sender, EventArgs e)
 175                 {
 176                         ConfirmInitState ();
 177                 }
 178
 179                 protected internal override void OnPreRender (EventArgs e)
 180                 {
 181                         preRendered = true;
 182                         EnsureDataBound ();
 183                         base.OnPreRender (e);
 184                 }
 185
 186                 internal Control FindDataSource ()
 187                 {
 188                         Control ctrl = null;
 189                         Control namingContainer = NamingContainer;
 190
 191                         while (namingContainer != null) {
 192                                 ctrl = namingContainer.FindControl (DataSourceID);
 193                                 if (ctrl != null)
 194                                         break;
 195                                 namingContainer = namingContainer.NamingContainer;
 196                         }
 197
 198                         return ctrl;
 199                 }
 200
 201                 protected abstract void PerformSelect ();
 202
 203                 protected abstract void ValidateDataSource (object dataSource);
 204
 205         }
 206 }
 207
 208 #endif
 209
 210