DataBoundControl.PerformDataBinding(IEnumerable) Method

Reference

Definition

Namespace:: System.Web.UI.WebControls

Assembly:: System.Web.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

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 -> unit

Protected 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.

Applies to

Delen via