CompositeDataBoundControl.CreateChildControls Metodo

Definizione

Crea la gerarchia dei controlli utilizzata per eseguire il rendering di un controllo composito associato a dati.Creates the control hierarchy that is used to render a composite data-bound control.

Overload

CreateChildControls()

Crea la gerarchia dei controlli utilizzata per eseguire il rendering di un controllo composito associato a dati in base ai valori memorizzati nello stato di visualizzazione.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)

Quando viene sottoposto a override in una classe astratta, crea la gerarchia dei controlli utilizzata per eseguire il rendering del controllo composito associato a dati in base ai valori dell'origine dati specificata.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()

Crea la gerarchia dei controlli utilizzata per eseguire il rendering di un controllo composito associato a dati in base ai valori memorizzati nello stato di visualizzazione.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 -> unit
Protected Friend Overrides Sub CreateChildControls ()

Commenti

Il CreateChildControls() metodo è un metodo helper utilizzato dalle classi che derivano CompositeDataBoundControl dalla classe per creare la gerarchia dei controlli per un controllo composito associato a dati.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. Questo overload del metodo crea la gerarchia dei controlli in base ai valori dello stato di visualizzazione, anziché direttamente dall'origine dati.This overload of the method creates the control hierarchy based on values from view state, rather than directly from the data source.

Vedi anche

CreateChildControls(IEnumerable, Boolean)

Quando viene sottoposto a override in una classe astratta, crea la gerarchia dei controlli utilizzata per eseguire il rendering del controllo composito associato a dati in base ai valori dell'origine dati specificata.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 -> int
Protected MustOverride Function CreateChildControls (dataSource As IEnumerable, dataBinding As Boolean) As Integer

Parametri

dataSource
IEnumerable

Oggetto IEnumerable che contiene i valori da associare al controllo.An IEnumerable that contains the values to bind to the control.

dataBinding
Boolean

true per indicare che il metodo CreateChildControls(IEnumerable, Boolean) viene chiamato durante l'associazione dati; in caso contrario, false.true to indicate that the CreateChildControls(IEnumerable, Boolean) is called during data binding; otherwise, false.

Restituisce

Il numero di elementi creato mediante il metodo CreateChildControls(IEnumerable, Boolean).The number of items created by the CreateChildControls(IEnumerable, Boolean).

Esempi

Nell'esempio di codice riportato di seguito viene illustrato CreateChildControls(IEnumerable, Boolean) come eseguire l'override del metodo in un controllo personalizzato per creare la gerarchia dei controlli.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

Commenti

Il CreateChildControls() metodo è un metodo helper utilizzato dalle classi che derivano CompositeDataBoundControl dalla classe per creare la gerarchia dei controlli per un controllo composito associato a dati.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. Quando si estende CompositeDataBoundControl la classe, è necessario eseguire CreateChildControls() l'override del metodo per creare una gerarchia dei controlli personalizzata.When extending the CompositeDataBoundControl class, you must override the CreateChildControls() method to create your own control hierarchy. Per ulteriori informazioni sulla creazione di un controllo composito, vedere sviluppo di controlli Server ASP.NET personalizzati.For more information on creating a composite control, see Developing Custom ASP.NET Server Controls.

Vedi anche

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