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) 2004-2010 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 using System.Collections;
  30 using System.ComponentModel;
  31 using System.Security.Permissions;
  32
  33 namespace System.Web.UI.WebControls
  34 {
  35         // CAS
  36         [AspNetHostingPermission (SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
  37         [AspNetHostingPermission (SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)]
  38         // attributes
  39         [DefaultProperty ("DataSourceID")]
  40         [DesignerAttribute ("System.Web.UI.Design.WebControls.BaseDataBoundControlDesigner, " + Consts.AssemblySystem_Design, "System.ComponentModel.Design.IDesigner")]
  41         public abstract class BaseDataBoundControl: WebControl
  42         {
  43                 static readonly object dataBoundEvent = new object ();
  44
  45                 EventHandlerList events = new EventHandlerList ();
  46                 object dataSource;
  47                 bool initialized;
  48                 bool preRendered;
  49                 bool requiresDataBinding;
  50
  51                 public event EventHandler DataBound {
  52                         add { events.AddHandler (dataBoundEvent, value); }
  53                         remove { events.RemoveHandler (dataBoundEvent, value); }
  54                 }
  55
  56                 protected BaseDataBoundControl ()
  57                 {
  58                 }
  59
  60                 /* Used for controls that used to inherit from
  61                  * WebControl, so the tag can propagate upwards
  62                  */
  63                 internal BaseDataBoundControl (HtmlTextWriterTag tag) : base (tag)
  64                 {
  65                 }
  66
  67                 [BindableAttribute (true)]
  68                 [ThemeableAttribute (false)]
  69                 [DefaultValueAttribute (null)]
  70                 [DesignerSerializationVisibilityAttribute (DesignerSerializationVisibility.Hidden)]
  71                 public virtual object DataSource {
  72                         get { return dataSource; }
  73                         set {
  74                                 if(value!=null)
  75                                         ValidateDataSource (value);
  76                                 dataSource = value;
  77                                 OnDataPropertyChanged ();
  78                         }
  79                 }
  80
  81                 [DefaultValueAttribute ("")]
  82                 [ThemeableAttribute (false)]
  83                 public virtual string DataSourceID {
  84                         get { return ViewState.GetString ("DataSourceID", String.Empty); }
  85                         set {
  86                                 ViewState["DataSourceID"] = value;
  87                                 OnDataPropertyChanged ();
  88                         }
  89                 }
  90
  91                 protected bool Initialized {
  92                         get { return initialized; }
  93                 }
  94
  95                 protected bool IsBoundUsingDataSourceID {
  96                         get { return DataSourceID.Length > 0; }
  97                 }
  98
  99                 protected bool RequiresDataBinding {
 100                         get { return requiresDataBinding; }
 101                         set {
 102                                 // MSDN: If you set the RequiresDataBinding
 103                                 // property to true when the data-bound control
 104                                 // has already begun to render its output to the
 105                                 // page, the current HTTP request is not a
 106                                 // callback, and you are using the DataSourceID
 107                                 // property to identify the data source control
 108                                 // to bind to, the DataBind method is called
 109                                 // immediately. In this case, the
 110                                 // RequiresDataBinding property is _not_ actually
 111                                 // set to true.
 112                                 //
 113                                 // LAMESPEC, the docs quoted above mention that
 114                                 // DataBind is called in the described
 115                                 // case. This is wrong since that way we don't
 116                                 // break recursion when the property is set from
 117                                 // within the OnSelect handler in user's
 118                                 // code. EnsureDataBound makes sure that no
 119                                 // recursive binding is performed. Also the
 120                                 // property DOES get set in this case (according
 121                                 // to tests)
 122                                 if (value && preRendered && IsBoundUsingDataSourceID && Page != null && !Page.IsCallback) {
 123                                         requiresDataBinding = true;
 124                                         EnsureDataBound ();
 125                                 } else
 126                                         requiresDataBinding = value;
 127                         }
 128                 }
 129 #if NET_4_0
 130                 public override bool SupportsDisabledAttribute {
 131                         get { return RenderingCompatibilityLessThan40; }
 132                 }
 133 #endif
 134                 protected void ConfirmInitState ()
 135                 {
 136                         initialized = true;
 137                 }
 138
 139                 public override void DataBind ()
 140                 {
 141                         PerformSelect ();
 142                 }
 143
 144                 protected virtual void EnsureDataBound ()
 145                 {
 146                         if (RequiresDataBinding && IsBoundUsingDataSourceID)
 147                                 DataBind ();
 148                 }
 149
 150                 protected virtual void OnDataBound (EventArgs e)
 151                 {
 152                         EventHandler eh = events [dataBoundEvent] as EventHandler;
 153                         if (eh != null)
 154                                 eh (this, e);
 155                 }
 156
 157                 protected virtual void OnDataPropertyChanged ()
 158                 {
 159                         if (Initialized)
 160                                 RequiresDataBinding = true;
 161                 }
 162
 163                 protected internal override void OnInit (EventArgs e)
 164                 {
 165                         base.OnInit (e);
 166                         Page.PreLoad += new EventHandler (OnPagePreLoad);
 167
 168                         if (!IsViewStateEnabled && Page != null && Page.IsPostBack)
 169                                 RequiresDataBinding = true;
 170                 }
 171
 172                 protected virtual void OnPagePreLoad (object sender, EventArgs e)
 173                 {
 174                         ConfirmInitState ();
 175                 }
 176
 177                 protected internal override void OnPreRender (EventArgs e)
 178                 {
 179                         preRendered = true;
 180                         EnsureDataBound ();
 181                         base.OnPreRender (e);
 182                 }
 183
 184                 internal Control FindDataSource ()
 185                 {
 186                         Control ctrl;
 187                         Control namingContainer = NamingContainer;
 188                         string dataSourceID = DataSourceID;
 189
 190                         while (namingContainer != null) {
 191                                 ctrl = namingContainer.FindControl (dataSourceID);
 192                                 if (ctrl != null)
 193                                         return ctrl;
 194                                 namingContainer = namingContainer.NamingContainer;
 195                         }
 196
 197                         return null;
 198                 }
 199
 200                 protected abstract void PerformSelect ();
 201
 202                 protected abstract void ValidateDataSource (object dataSource);
 203
 204         }
 205 }