DataBoundControl.PerformDataBinding(IEnumerable) Method
Definition
Important
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When overridden in a derived class, binds data from the data source to the control.
protected public:
virtual void PerformDataBinding(System::Collections::IEnumerable ^ data);protected internal virtual void PerformDataBinding (System.Collections.IEnumerable data);abstract member PerformDataBinding : System.Collections.IEnumerable -> unit
override this.PerformDataBinding : System.Collections.IEnumerable -> unitProtected Friend Overridable Sub PerformDataBinding (data As IEnumerable)Parameters
- data
- IEnumerable
The IEnumerable list of data returned from a PerformSelect() method call.
Examples
The following code example demonstrates how to implement the PerformDataBinding method in a class derived from DataBoundControl. The TextBoxSet control creates a TextBox control for each data item it is bound to. This code example is part of a larger example provided for the DataBoundControl class.
protected override void PerformDataBinding(IEnumerable retrievedData) {
base.PerformDataBinding(retrievedData);
// If the data is retrieved from an IDataSource as an
// IEnumerable collection, attempt to bind its values to a
// set of TextBox controls.
if (retrievedData != null) {
foreach (object dataItem in retrievedData) {
TextBox box = new TextBox();
// The dataItem is not just a string, but potentially
// a System.Data.DataRowView or some other container.
// If DataTextField is set, use it to determine which
// field to render. Otherwise, use the first field.
if (DataTextField.Length > 0) {
box.Text = DataBinder.GetPropertyValue(dataItem,
DataTextField, null);
}
else {
PropertyDescriptorCollection props =
TypeDescriptor.GetProperties(dataItem);
// Set the "default" value of the TextBox.
box.Text = String.Empty;
// Set the true data-bound value of the TextBox,
// if possible.
if (props.Count >= 1) {
if (null != props[0].GetValue(dataItem)) {
box.Text = props[0].GetValue(dataItem).ToString();
}
}
}
BoxSet.Add(box);
}
}
}
Protected Overrides Sub PerformDataBinding(ByVal retrievedData As IEnumerable)
MyBase.PerformDataBinding(retrievedData)
' If the data is retrieved from an IDataSource as an IEnumerable
' collection, attempt to bind its values to a set of TextBox controls.
If Not (retrievedData Is Nothing) Then
Dim dataItem As Object
For Each dataItem In retrievedData
Dim box As New TextBox()
' The dataItem is not just a string, but potentially
' a System.Data.DataRowView or some other container.
' If DataTextField is set, use it to determine which
' field to render. Otherwise, use the first field.
If DataTextField.Length > 0 Then
box.Text = DataBinder.GetPropertyValue( _
dataItem, DataTextField, Nothing)
Else
Dim props As PropertyDescriptorCollection = _
TypeDescriptor.GetProperties(dataItem)
' Set the "default" value of the TextBox.
box.Text = String.Empty
' Set the true data-bound value of the TextBox,
' if possible.
If props.Count >= 1 Then
If props(0).GetValue(dataItem) IsNot Nothing Then
box.Text = props(0).GetValue(dataItem).ToString()
End If
End If
End If
BoxSet.Add(box)
Next dataItem
End If
End Sub
Remarks
Implement this method instead of the DataBind method when you derive a data-bound control from the DataBoundControl class. Placing your control's data-binding logic in PerformDataBinding enables you to avoid the DataBinding and DataBound events being raised in the wrong order.
While the base DataBoundControl class provides no specific implementation for this method, the PerformDataBinding method is called by the PerformSelect method to bind the values of any user interface (UI) controls to the data that is retrieved by the PerformSelect method.
