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

   1 //
   2 // System.Web.UI.WebControls.DataBoundControl
   3 //
   4 // Authors:
   5 //      Ben Maurer (bmaurer@users.sourceforge.net)
   6 //
   7 // (C) 2003 Ben Maurer
   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 #if NET_2_0
  32 using System.Collections;
  33 using System.Collections.Specialized;
  34 using System.Text;
  35 using System.Web.Util;
  36 using System.ComponentModel;
  37
  38 namespace System.Web.UI.WebControls {
  39         public abstract class DataBoundControl : WebControl
  40         {
  41                 public event EventHandler DataBound;
  42
  43                 protected DataBoundControl ()
  44                 {
  45                 }
  46
  47                 public sealed override void DataBind ()
  48                 {
  49                         PerformDataBinding ();
  50                         RequiresDataBinding = false;
  51                         OnDataBound (EventArgs.Empty);
  52                 }
  53
  54                 protected void EnsureDataBound ()
  55                 {
  56                         if (RequiresDataBinding && DataSourceID != "")
  57                                 DataBind ();
  58                 }
  59
  60                 protected virtual object GetDataSourceObject()
  61                 {
  62                         if (DataSourceID != "")
  63                                 return (IDataSource) NamingContainer.FindControl (DataSourceID);
  64
  65                         return DataSource;
  66                 }
  67
  68
  69                 protected virtual IEnumerable GetResolvedDataSource ()
  70                 {
  71                         if (DataSource != null && DataSourceID != "")
  72                                 throw new HttpException ();
  73
  74                         IDataSource ds = GetDataSourceObject () as IDataSource;
  75                         if (ds != null && DataSourceID != "")
  76                                 return ds.GetView (DataMember).Select ();
  77                         else if (DataSource != null)
  78                                 return DataSourceHelper.GetResolvedDataSource (DataSource, DataMember);
  79                         else
  80                                 return null;
  81                 }
  82
  83                 protected bool IsBoundToDataSourceControl()
  84                 {
  85                         return (GetDataSourceObject () is IDataSource) && DataSourceID != "";
  86                 }
  87
  88                 protected virtual void OnDataBound(EventArgs e) {
  89                         if (DataBound != null)
  90                                 DataBound (this, e);
  91                 }
  92
  93                 protected virtual void OnDataPropertyChanged ()
  94                 {
  95                         this.RequiresDataBinding = true;
  96                 }
  97
  98                 protected virtual void OnDataSourceChanged (object sender, EventArgs e)
  99                 {
 100                         RequiresDataBinding = true;
 101                 }
 102
 103                 // should be `internal protected' (why, oh WHY did they do that !?!)
 104                 protected override void OnInit (EventArgs e)
 105                 {
 106                         base.OnInit(e);
 107                         inited = true;
 108                         if (!Page.IsPostBack)
 109                                 RequiresDataBinding = true;
 110                 }
 111
 112                 // should be `internal protected' (why, oh WHY did they do that !?!)
 113                 protected override void OnLoad (EventArgs e)
 114                 {
 115                         IDataSource ds = GetDataSourceObject () as IDataSource;
 116                         if (ds != null && DataSourceID != "")
 117                                 ds.DataSourceChanged += new EventHandler (OnDataSourceChanged);
 118
 119                         base.OnLoad(e);
 120                 }
 121
 122                 // should be `internal protected' (why, oh WHY did they do that !?!)
 123                 protected override void OnPreRender (EventArgs e)
 124                 {
 125                         EnsureDataBound ();
 126                         base.OnPreRender (e);
 127                 }
 128
 129                 protected virtual void PerformDataBinding ()
 130                 {
 131                         OnDataBinding(EventArgs.Empty);
 132                 }
 133
 134
 135                 protected virtual void ValidateDataSource (object dataSource)
 136                 {
 137                         if (dataSource is IListSource || dataSource is IEnumerable)
 138                                 return;
 139                         throw new ArgumentException ();
 140                 }
 141
 142
 143                 public string DataMember
 144                 {
 145                         get {
 146                                 object o = ViewState["DataMember"];
 147                                 if(o!=null)
 148                                         return (string)o;
 149                                 return String.Empty;
 150                         }
 151                         set {
 152                                 ViewState["DataMember"] = value;
 153                         }
 154                 }
 155
 156                 object dataSource;
 157                 public virtual object DataSource
 158                 {
 159                         get {
 160                                 return dataSource;
 161                         }
 162                         set {
 163                                 ValidateDataSource (value);
 164                                 dataSource = value;
 165                         }
 166                 }
 167
 168                 public virtual string DataSourceID {
 169                         get {
 170                                 object o = ViewState ["DataSourceID"];
 171                                 if (o != null)
 172                                         return (string)o;
 173
 174                                 return String.Empty;
 175                         }
 176                         set {
 177                                 if (inited)
 178                                         RequiresDataBinding = true;
 179
 180                                 ViewState ["DataSourceID"] = value;
 181                         }
 182                 }
 183
 184                 bool requiresDataBinding;
 185                 protected bool RequiresDataBinding {
 186                         get { return requiresDataBinding; }
 187                         set { requiresDataBinding = value; }
 188                 }
 189
 190                 protected bool inited;
 191         }
 192 }
 193 #endif
 194