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Control.OnDataBinding Method

Raises the DataBinding event.

[Visual Basic]
Protected Overridable Sub OnDataBinding( _
   ByVal e As EventArgs _
)
[C#]
protected virtual void OnDataBinding(
 EventArgs e
);
[C++]
protected: virtual void OnDataBinding(
 EventArgs* e
);
[JScript]
protected function OnDataBinding(
   e : EventArgs
);

Parameters

e
An EventArgs object that contains the event data.

Remarks

This method notifies a server control to perform any data binding logic that is associated with it.

If you want to handle the DataBinding event, you should override this event-handling method. This ensures that all delegates attached to the DataBinding event are invoked.

Example

The following example demonstrates how to override the OnDataBinding method to add child controls to the parent control from a data source.

[Visual Basic] 
' Override to create the repeated items from the DataSource.
Protected Overrides Sub OnDataBinding(E As EventArgs)
    MyBase.OnDataBinding(e)

    If Not DataSource Is Nothing
        ' Clear any existing child controls.
        Controls.Clear()
        ' Clear any previous view state for the existing child controls.
        ClearChildViewState()

        ' Iterate over the DataSource, creating a new item for each data item.
        Dim DataEnum As IEnumerator = DataSource.GetEnumerator()
        Dim I As Integer = 0
        Do While (DataEnum.MoveNext())

            ' Create an item.
            Dim Item As RepeaterItemVB = New RepeaterItemVB(I, DataEnum.Current)
            ' Initialize the item from the template.
            ItemTemplate.InstantiateIn(Item)
            ' Add the item to the ControlCollection.
            Controls.Add(Item)

            I = I + 1
        Loop

        ' Prevent child controls from being created again.
        ChildControlsCreated = true
        ' Store the number of items created in view state for postback scenarios.
        ViewState("NumItems") = I
    End If
End Sub

[C#] 
// Override to create the repeated items from the DataSource.
protected override void OnDataBinding(EventArgs e) {
    base.OnDataBinding(e);

    if (DataSource != null) {
        // Clear any existing child controls.
        Controls.Clear();
        // Clear any previous view state for the existing child controls.
        ClearChildViewState();

        // Iterate over the DataSource, creating a new item for each data item.
        IEnumerator dataEnum = DataSource.GetEnumerator();
        int i = 0;
        while(dataEnum.MoveNext()) {

            // Create an item.
            RepeaterItem item = new RepeaterItem(i, dataEnum.Current);
            // Initialize the item from the template.
            ItemTemplate.InstantiateIn(item);
            // Add the item to the ControlCollection.
            Controls.Add(item);

            i++;
        }

        // Prevent child controls from being created again.
        ChildControlsCreated = true;
        // Store the number of items created in view state for postback scenarios.
        ViewState["NumItems"] = i;
    }
}

[C++] 
// Override to create the repeated items from the DataSource.
protected:
void OnDataBinding(EventArgs * e) 
{
   __super::OnDataBinding(e);

   if (DataSource != 0) 
   {
      // Clear any existing child controls.
      Controls->Clear();
      // Clear any previous view state for the existing child controls.
      ClearChildViewState();

      // Iterate over the DataSource, creating a new item for each data item.
      IEnumerator* dataEnum = DataSource->GetEnumerator();
      int i = 0;
      while(dataEnum->MoveNext()) 
      {
         // Create an item.
         RepeaterItem* item = new RepeaterItem(i, dataEnum->Current);
         // Initialize the item from the template.
         ItemTemplate->InstantiateIn(item);
         // Add the item to the ControlCollection.
         Controls->Add(item);
         i++;
      }

      // Prevent child controls from being created again.
      ChildControlsCreated = true;
      // Store the number of items created in view state for postback scenarios.
      ViewState->Item[S"NumItems"] = __box(i);
   }
}

[JScript] 
// Override to create the repeated items from the DataSource.
protected override function OnDataBinding(e : EventArgs) {
    super.OnDataBinding(e);

    if (DataSource != null) {
        // Clear any existing child controls.
        Controls.Clear();
        // Clear any previous view state for the existing child controls.
        ClearChildViewState();

        // Iterate over the DataSource, creating a new item for each data item.
        var dataEnum : IEnumerator = DataSource.GetEnumerator();
        var i : int = 0;
        while(dataEnum.MoveNext()) {

            // Create an item.
            var item : RepeaterItem = new RepeaterItem(i, dataEnum.Current);
            // Initialize the item from the template.
            ItemTemplate.InstantiateIn(item);
            // Add the item to the ControlCollection.
            Controls.Add(item);

            i++;
        }

        // Prevent child controls from being created again.
        ChildControlsCreated = true;
        // Store the number of items created in view state for postback scenarios.
        ViewState["NumItems"] = i;
    }
}

Requirements

Platforms: Windows 2000, Windows XP Professional, Windows Server 2003 family

See Also

Control Class | Control Members | System.Web.UI Namespace | DataBinding | DataBind

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