CompositeDataBoundControl.CreateChildControls Method (IEnumerable, Boolean)


The .NET API Reference documentation has a new home. Visit the .NET API Browser on to see the new experience.

When overridden in an abstract class, creates the control hierarchy that is used to render the composite data-bound control based on the values from the specified data source.

Namespace:   System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

Protected MustOverride Function CreateChildControls (
	dataSource As IEnumerable,
	dataBinding As Boolean
) As Integer


Type: System.Collections.IEnumerable

An IEnumerable that contains the values to bind to the control.

Type: System.Boolean

true to indicate that the CreateChildControls(IEnumerable, Boolean) is called during data binding; otherwise, false.

Return Value

Type: System.Int32

The number of items created by the CreateChildControls(IEnumerable, Boolean).

The CreateChildControls() method is a helper method that is used by classes that derive from the CompositeDataBoundControl class to create the control hierarchy for a composite data-bound control. When extending the CompositeDataBoundControl class, you must override the CreateChildControls() method to create your own control hierarchy. For more information on creating a composite control, see Developing Custom ASP.NET Server Controls.

The following code example demonstrates how to override the CreateChildControls(IEnumerable, Boolean) method in a custom control to create the control hierarchy.

Imports System
Imports System.Collections
Imports System.Data.Common
Imports System.Web.UI
Imports System.Web.UI.WebControls

Namespace Samples.AspNet.VB

    Public Class SimpleSpreadsheetControl
        Inherits CompositeDataBoundControl

        Protected table As New Table()

        Public Overridable ReadOnly Property Rows() As TableRowCollection
                Return table.Rows
            End Get
        End Property

        Protected Overrides Function CreateChildControls(ByVal dataSource As IEnumerable, ByVal dataBinding As Boolean) As Integer

            Dim count As Integer = 0
            ' If dataSource is not Nothing, iterate through it and
            ' extract each element from it as a row, then
            ' create a SimpleSpreadsheetRow and add it to the
            ' rows collection.
            If Not (dataSource Is Nothing) Then

                Dim row As SimpleSpreadsheetRow
                Dim e As IEnumerator = dataSource.GetEnumerator()

                While e.MoveNext()
                    Dim datarow As Object = e.Current
                    row = New SimpleSpreadsheetRow(count, datarow)
                    count += 1
                End While

            End If
            Return count
        End Function 'CreateChildControls
    End Class 'SimpleSpreadsheetControl

    Public Class SimpleSpreadsheetRow
        Inherits TableRow
        Implements IDataItemContainer

        Private dataObj As Object
        Private _itemIndex As Integer

        Public Sub New(ByVal itemIndex As Integer, ByVal o As Object)
            dataObj = o
            _itemIndex = itemIndex
        End Sub 'NewNew

        Public Overridable ReadOnly Property Data() As Object
                Return dataObj
            End Get
        End Property

        ReadOnly Property DataItem() As Object Implements IDataItemContainer.DataItem
                Return Data
            End Get
        End Property

        ReadOnly Property DataItemIndex() As Integer Implements IDataItemContainer.DataItemIndex
                Return _itemIndex
            End Get
        End Property

        ReadOnly Property DisplayIndex() As Integer Implements IDataItemContainer.DisplayIndex
                Return _itemIndex
            End Get
        End Property
        Protected Overrides Sub RenderContents(ByVal writer As HtmlTextWriter)

            If Not (Data Is Nothing) Then
                If TypeOf Data Is System.Data.Common.DbDataRecord Then
                    Dim temp As DbDataRecord = CType(Data, DbDataRecord)
                    Dim i As Integer

                    While i < temp.FieldCount
                        i += 1
                    End While
                    writer.Write(("<TD>" + Data.ToString() + "</TD>"))
                End If

                writer.Write("<TD>This is a test</TD>")
            End If
        End Sub 'RenderContents
    End Class 'SimpleSpreadsheetRow
End Namespace

.NET Framework
Available since 2.0
Return to top