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                                 if (value && preRendered && IsBoundUsingDataSourceID && Page != null && !Page.IsCallback)
 112                                         EnsureDataBound ();
 113                                 else
 114                                         requiresDataBinding = value;
 115                         }
 116                 }
 117
 118                 protected void ConfirmInitState ()
 119                 {
 120                         initialized = true;
 121                 }
 122
 123                 public override void DataBind ()
 124                 {
 125                         PerformSelect ();
 126                 }
 127
 128                 protected virtual void EnsureDataBound ()
 129                 {
 130                         if (RequiresDataBinding && IsBoundUsingDataSourceID)
 131                                 DataBind ();
 132                 }
 133
 134                 protected virtual void OnDataBound (EventArgs e)
 135                 {
 136                         if (DataBound != null)
 137                                 DataBound (this, e);
 138                 }
 139
 140                 protected virtual void OnDataPropertyChanged ()
 141                 {
 142                         if (Initialized)
 143                                 RequiresDataBinding = true;
 144                 }
 145
 146                 protected internal override void OnInit (EventArgs e)
 147                 {
 148                         base.OnInit (e);
 149                         Page.PreLoad += new EventHandler (OnPagePreLoad);
 150
 151                         if (!IsViewStateEnabled && Page != null && Page.IsPostBack)
 152                                 RequiresDataBinding = true;
 153                 }
 154
 155                 protected virtual void OnPagePreLoad (object sender, EventArgs e)
 156                 {
 157                         ConfirmInitState ();
 158                 }
 159
 160                 protected internal override void OnPreRender (EventArgs e)
 161                 {
 162                         preRendered = true;
 163                         EnsureDataBound ();
 164                         base.OnPreRender (e);
 165                 }
 166
 167                 internal Control FindDataSource ()
 168                 {
 169                         Control ctrl = null;
 170                         Control namingContainer = NamingContainer;
 171
 172                         while (namingContainer != null) {
 173                                 ctrl = namingContainer.FindControl (DataSourceID);
 174                                 if (ctrl != null)
 175                                         break;
 176                                 namingContainer = namingContainer.NamingContainer;
 177                         }
 178
 179                         return ctrl;
 180                 }
 181
 182                 protected abstract void PerformSelect ();
 183
 184                 protected abstract void ValidateDataSource (object dataSource);
 185
 186         }
 187 }
 188
 189 #endif
 190
 191