IDataItemContainer Interface

Definitie

public interface class IDataItemContainer : System::Web::UI::INamingContainer

public interface IDataItemContainer : System.Web.UI.INamingContainer

type IDataItemContainer = interface
    interface INamingContainer

Public Interface IDataItemContainer
Implements INamingContainer

Afgeleid

System.Web.UI.WebControls.DataGridItem

System.Web.UI.WebControls.DataListItem

System.Web.UI.WebControls.DetailsView

System.Web.UI.WebControls.FormView

System.Web.UI.WebControls.GridViewRow

Meer…

Implementeringen

INamingContainer

Voorbeelden

In het volgende codevoorbeeld ziet u hoe u de IDataItemContainer interface gebruikt. Het SimpleSpreadsheetControl is een besturingselement dat gegevens in tabelvorm weergeeft, vergelijkbaar met een DataGrid of GridView besturingselement. Het bevat een set SimpleSpreadsheetRow objecten.

De SimpleSpreadsheetRow klasse is een containerklasse die de IDataItemContainer interface implementeert. Hoewel in dit voorbeeld de eigenschap van het gegevensitem intuïtief een naam Dataheeft, kan de DataItem eigenschap worden geïmplementeerd om toe te wijzen aan een eigenschap of retourwaarde van een methode.

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

In het volgende codevoorbeeld ziet u hoe u de gegevens in een Access-database kunt weergeven met het SimpleSpreadsheetControl en AccessDataSource besturingselement.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS"
    Assembly="Samples.AspNet.CS"  %>
<%@ Page language="c#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>IDataItemContainer - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

      <aspSample:SimpleSpreadsheetControl
          id="SimpleSpreadsheet1"
          runat="server"
          datasourceid="AccessDataSource1" />

      <asp:accessdatasource
          id="AccessDataSource1"
          runat="server"
          datasourcemode="DataReader"
          datafile="Northwind.mdb"
          SelectCommand="SELECT OrderID,CustomerID,OrderDate,RequiredDate,
          ShippedDate FROM Orders WHERE EmployeeID = (SELECT EmployeeID 
          FROM Employees WHERE LastName = 'King')">
      </asp:accessdatasource>

    </form>
  </body>
</html>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB"
    Assembly="Samples.AspNet.VB" %>
<%@ Page language="vb" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>IDataItemContainer - VB Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

      <aspSample:SimpleSpreadsheetControl
          id="SimpleSpreadsheet1"
          runat="server"
          datasourceid="AccessDataSource1" />

      <asp:accessdatasource
          id="AccessDataSource1"
          runat="server"
          datasourcemode="DataReader"
          datafile="Northwind.mdb"
          SelectCommand="SELECT OrderID,CustomerID,OrderDate,RequiredDate,ShippedDate
          FROM Orders WHERE EmployeeID =
          (SELECT EmployeeID FROM Employees WHERE LastName = 'King')">
      </asp:accessdatasource>

    </form>
  </body>
</html>

Opmerkingen

Containerklassen die de IDataItemContainer interface implementeren, kunnen opgeven welke eigenschappen het gegevensitem identificeren voor bewerkingen voor gegevensbinding, zoals late binding met de DataBinder klasse.

Zie ook

• DataBinder
• FormView
• DetailsView
• GridViewRow