CompositeDataBoundControl.CreateChildControls Method
Definition
Important
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Creates the control hierarchy that is used to render a composite data-bound control.
Overloads
| CreateChildControls() |
Creates the control hierarchy that is used to render a composite data-bound control based on the values that are stored in view state. |
| CreateChildControls(IEnumerable, Boolean) |
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. |
CreateChildControls()
Creates the control hierarchy that is used to render a composite data-bound control based on the values that are stored in view state.
protected public:
override void CreateChildControls();protected internal override void CreateChildControls ();override this.CreateChildControls : unit -> unitProtected Friend Overrides Sub CreateChildControls ()Remarks
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. This overload of the method creates the control hierarchy based on values from view state, rather than directly from the data source.
See also
Applies to
CreateChildControls(IEnumerable, Boolean)
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.
protected:
abstract int CreateChildControls(System::Collections::IEnumerable ^ dataSource, bool dataBinding);protected abstract int CreateChildControls (System.Collections.IEnumerable dataSource, bool dataBinding);override this.CreateChildControls : System.Collections.IEnumerable * bool -> intProtected MustOverride Function CreateChildControls (dataSource As IEnumerable, dataBinding As Boolean) As IntegerParameters
- dataSource
- IEnumerable
An IEnumerable that contains the values to bind to the control.
- dataBinding
- Boolean
true to indicate that the CreateChildControls(IEnumerable, Boolean) is called during data binding; otherwise, false.
Returns
The number of items created by the CreateChildControls(IEnumerable, Boolean).
Examples
The following code example demonstrates how to override the CreateChildControls(IEnumerable, Boolean) method in a custom control to create the control hierarchy.
using System;
using System.Collections;
using System.Data.Common;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace Samples.AspNet.CS
{
public class SimpleSpreadsheetControl : CompositeDataBoundControl
{
protected Table table = new Table();
public virtual TableRowCollection Rows
{
get
{
return table.Rows;
}
}
protected override int CreateChildControls(IEnumerable dataSource, bool dataBinding)
{
int count = 0;
// If dataSource is not null, iterate through it and
// extract each element from it as a row, then
// create a SimpleSpreadsheetRow and add it to the
// rows collection.
if (dataSource != null)
{
SimpleSpreadsheetRow row;
IEnumerator e = dataSource.GetEnumerator();
while (e.MoveNext())
{
object datarow = e.Current;
row = new SimpleSpreadsheetRow(count, datarow);
this.Rows.Add(row);
++count;
}
Controls.Add(table);
}
return count;
}
}
//
//
public class SimpleSpreadsheetRow : TableRow, IDataItemContainer
{
private object data;
private int _itemIndex;
public SimpleSpreadsheetRow(int itemIndex, object o)
{
data = o;
_itemIndex = itemIndex;
}
public virtual object Data
{
get
{
return data;
}
}
object IDataItemContainer.DataItem
{
get
{
return Data;
}
}
int IDataItemContainer.DataItemIndex
{
get
{
return _itemIndex;
}
}
int IDataItemContainer.DisplayIndex
{
get
{
return _itemIndex;
}
}
protected override void RenderContents(HtmlTextWriter writer)
{
if (Data != null)
{
if (Data is System.Data.Common.DbDataRecord)
{
DbDataRecord temp = (DbDataRecord)Data;
for (int i = 0; i < temp.FieldCount; ++i)
{
writer.Write("<TD>");
writer.Write(temp.GetValue(i).ToString());
writer.Write("</TD>");
}
}
else
{
writer.Write("<TD>" + Data.ToString() + "</TD>");
}
}
else
{
writer.Write("<TD>This is a test</TD>");
}
}
}
}
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
Get
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)
Me.Rows.Add(row)
count += 1
End While
Controls.Add(table)
End If
Return count
End Function 'CreateChildControls
End Class
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
Public Overridable ReadOnly Property Data() As Object
Get
Return dataObj
End Get
End Property
ReadOnly Property DataItem() As Object Implements IDataItemContainer.DataItem
Get
Return Data
End Get
End Property
ReadOnly Property DataItemIndex() As Integer Implements IDataItemContainer.DataItemIndex
Get
Return _itemIndex
End Get
End Property
ReadOnly Property DisplayIndex() As Integer Implements IDataItemContainer.DisplayIndex
Get
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
writer.Write("<TD>")
writer.Write(temp.GetValue(i).ToString())
writer.Write("</TD>")
i += 1
End While
Else
writer.Write(("<TD>" + Data.ToString() + "</TD>"))
End If
Else
writer.Write("<TD>This is a test</TD>")
End If
End Sub
End Class
End Namespace
Remarks
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.
