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 #if NET_2_0
  11 using System.Collections;
  12 using System.Collections.Specialized;
  13 using System.Text;
  14 using System.Web.Util;
  15 using System.ComponentModel;
  16
  17 namespace System.Web.UI.WebControls {
  18         public abstract class DataBoundControl : WebControl
  19         {
  20                 public event EventHandler DataBound;
  21
  22                 protected DataBoundControl ()
  23                 {
  24                 }
  25
  26                 public sealed override void DataBind ()
  27                 {
  28                         PerformDataBinding ();
  29                         RequiresDataBinding = false;
  30                         OnDataBound (EventArgs.Empty);
  31                 }
  32
  33                 protected void EnsureDataBound ()
  34                 {
  35                         if (RequiresDataBinding && DataSourceID != "")
  36                                 DataBind ();
  37                 }
  38
  39                 protected virtual object GetDataSourceObject()
  40                 {
  41                         if (DataSourceID != "")
  42                                 return (IDataSource) NamingContainer.FindControl (DataSourceID);
  43
  44                         return DataSource;
  45                 }
  46
  47
  48                 protected virtual IEnumerable GetResolvedDataSource ()
  49                 {
  50                         if (DataSource != null && DataSourceID != "")
  51                                 throw new HttpException ();
  52
  53                         IDataSource ds = GetDataSourceObject () as IDataSource;
  54                         if (ds != null && DataSourceID != "")
  55                                 return ds.GetView (DataMember).Select ();
  56                         else if (DataSource != null)
  57                                 return DataSourceHelper.GetResolvedDataSource (DataSource, DataMember);
  58                         else
  59                                 return null;
  60                 }
  61
  62                 protected bool IsBoundToDataSourceControl()
  63                 {
  64                         return (GetDataSourceObject () is IDataSource) && DataSourceID != "";
  65                 }
  66
  67                 protected virtual void OnDataBound(EventArgs e) {
  68                         if (DataBound != null)
  69                                 DataBound (this, e);
  70                 }
  71
  72                 protected virtual void OnDataPropertyChanged ()
  73                 {
  74                         this.RequiresDataBinding = true;
  75                 }
  76
  77                 protected virtual void OnDataSourceChanged (object sender, EventArgs e)
  78                 {
  79                         RequiresDataBinding = true;
  80                 }
  81
  82                 // should be `internal protected' (why, oh WHY did they do that !?!)
  83                 protected override void OnInit (EventArgs e)
  84                 {
  85                         base.OnInit(e);
  86                         inited = true;
  87                         if (!Page.IsPostBack)
  88                                 RequiresDataBinding = true;
  89                 }
  90
  91                 // should be `internal protected' (why, oh WHY did they do that !?!)
  92                 protected override void OnLoad (EventArgs e)
  93                 {
  94                         IDataSource ds = GetDataSourceObject () as IDataSource;
  95                         if (ds != null && DataSourceID != "")
  96                                 ds.DataSourceChanged += new EventHandler (OnDataSourceChanged);
  97
  98                         base.OnLoad(e);
  99                 }
 100
 101                 // should be `internal protected' (why, oh WHY did they do that !?!)
 102                 protected override void OnPreRender (EventArgs e)
 103                 {
 104                         EnsureDataBound ();
 105                         base.OnPreRender (e);
 106                 }
 107
 108                 protected virtual void PerformDataBinding ()
 109                 {
 110                         OnDataBinding(EventArgs.Empty);
 111                 }
 112
 113
 114                 protected virtual void ValidateDataSource (object dataSource)
 115                 {
 116                         if (dataSource is IListSource || dataSource is IEnumerable)
 117                                 return;
 118                         throw new ArgumentException ();
 119                 }
 120
 121
 122                 public string DataMember
 123                 {
 124                         get {
 125                                 object o = ViewState["DataMember"];
 126                                 if(o!=null)
 127                                         return (string)o;
 128                                 return String.Empty;
 129                         }
 130                         set {
 131                                 ViewState["DataMember"] = value;
 132                         }
 133                 }
 134
 135                 object dataSource;
 136                 public virtual object DataSource
 137                 {
 138                         get {
 139                                 return dataSource;
 140                         }
 141                         set {
 142                                 ValidateDataSource (value);
 143                                 dataSource = value;
 144                         }
 145                 }
 146
 147                 public virtual string DataSourceID {
 148                         get {
 149                                 object o = ViewState ["DataSourceID"];
 150                                 if (o != null)
 151                                         return (string)o;
 152
 153                                 return String.Empty;
 154                         }
 155                         set {
 156                                 if (inited)
 157                                         RequiresDataBinding = true;
 158
 159                                 ViewState ["DataSourceID"] = value;
 160                         }
 161                 }
 162
 163                 bool requiresDataBinding;
 164                 protected bool RequiresDataBinding {
 165                         get { return requiresDataBinding; }
 166                         set { requiresDataBinding = value; }
 167                 }
 168
 169                 protected bool inited;
 170         }
 171 }
 172 #endif
 173