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