TableCallback デリゲートとは? わかりやすく解説

TableCallback デリゲート

メモ : このデリゲートは、.NET Framework version 2.0新しく追加されたものです。

プロバイダからテーブル データ取得するときに呼び出すメソッド参照します。

名前空間: System.Web.UI.WebControls.WebParts
アセンブリ: System.Web (system.web.dll 内)
構文構文

Public Delegate Sub TableCallback
 ( _
    tableData As ICollection _
)
Dim instance As New TableCallback(AddressOf
 HandlerMethod)
public delegate void TableCallback (
    ICollection tableData
)
public delegate void TableCallback (
    ICollection^ tableData
)
/** @delegate */
public delegate void TableCallback (
    ICollection tableData
)
JScript では、デリゲート使用できますが、新規に宣言することはできません。

パラメータ

tableData

プロバイダから取得するデータ

解説解説
使用例使用例

テーブル形式データプロバイダとして動作するTableProviderWebPart という名前の Web パーツ コントロールコード例次に示します。このコントロールには、TableCallback 型のパラメータ受け取る、GetTableData メソッド実装含まれます。このメソッドは、テーブル データを渡す TableCallback デリゲート表されるメソッド呼び出します。

Imports System
Imports System.Collections
Imports System.ComponentModel
Imports System.Data
Imports System.Reflection
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts

'This sample code creates a Web Parts control that acts as a provider
 of table data.
Namespace Samples.AspNet.VB.Controls

    Public NotInheritable Class
 TableProviderWebPart
        Inherits WebPart
        Implements IWebPartTable

        Private _table As DataTable


        Public Sub New()
            _table = New DataTable()

            Dim col As New
 DataColumn()
            col.DataType = GetType(String)
            col.ColumnName = "Name"
            _table.Columns.Add(col)

            col = New DataColumn()
            col.DataType = GetType(String)
            col.ColumnName = "Address"
            _table.Columns.Add(col)

            col = New DataColumn()
            col.DataType = GetType(Integer)
            col.ColumnName = "ZIP Code"
            _table.Columns.Add(col)

            Dim row As DataRow = _table.NewRow()
            row("Name") = "John
 Q. Public"
            row("Address") = "123
 Main Street"
            row("ZIP Code") = 98000
            _table.Rows.Add(row)

        End Sub 'New

        <ConnectionProvider("Table")> _
        Public Function GetConnectionInterface()
 As IWebPartTable
            Return New TableProviderWebPart()

        End Function 'GetConnectionInterface

        Public ReadOnly Property
 Schema() As PropertyDescriptorCollection _
            Implements IWebPartTable.Schema
            Get
                Return TypeDescriptor.GetProperties(_table.DefaultView(0))
            End Get
        End Property

        Public Property ConnectionPointEnabled()
 As Boolean
            Get
                Dim o As Object
                o = ViewState("ConnectionPointEnabled")
                If Not (o Is
 Nothing) Then
                    Return CBool(o)
                Else
                    Return True
                End If

            End Get
            Set(ByVal value As
 Boolean)
                ViewState("ConnectionPointEnabled")
 = value
            End Set
        End Property

        Public Sub GetTableData(ByVal
 callback As TableCallback) _
            Implements IWebPartTable.GetTableData
            callback(_table.Rows)

        End Sub 'GetTableData
    End Class 'TableProviderWebPart
           

End Namespace
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Reflection;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
//This sample code creates a Web Parts control that acts as a provider
 of table data.
namespace Samples.AspNet.CS.Controls
{
    public sealed class TableProviderWebPart
 : WebPart, IWebPartTable
    {
        DataTable _table;

        public TableProviderWebPart()
        {
            _table = new DataTable();

            DataColumn col = new DataColumn();
            col.DataType = typeof(string);
            col.ColumnName = "Name";
            _table.Columns.Add(col);

            col = new DataColumn();
            col.DataType = typeof(string);
            col.ColumnName = "Address";
            _table.Columns.Add(col);

            col = new DataColumn();
            col.DataType = typeof(int);
            col.ColumnName = "ZIP Code";
            _table.Columns.Add(col);

            DataRow row = _table.NewRow();
            row["Name"] = "John Q. Public";
            row["Address"] = "123 Main Street";
            row["ZIP Code"] = 98000;
            _table.Rows.Add(row);
        }

        public PropertyDescriptorCollection Schema
        {
            get
            {
                return TypeDescriptor.GetProperties(_table.DefaultView[0]);
            }
        }
        
        public void GetTableData(TableCallback
 callback)
        {
            callback(_table.Rows);
        }
        

        public bool ConnectionPointEnabled
        {
            get
            {
                object o = ViewState["ConnectionPointEnabled"];
                return (o != null) ? (bool)o
 : true;
            }
            set
            {
                ViewState["ConnectionPointEnabled"] = value;
            }
        }

        [ConnectionProvider("Table")]
        public IWebPartTable GetConnectionInterface()
        {
            return new TableProviderWebPart();
        }

        
        public class TableProviderConnectionPoint
 : ProviderConnectionPoint
        {
            public TableProviderConnectionPoint(MethodInfo callbackMethod,
 
                Type interfaceType, Type controlType,
                string name, string id, bool
 allowsMultipleConnections)
                : base(callbackMethod, interfaceType, controlType
,
                    name, id, allowsMultipleConnections)
            {
            }
            
            
            public override bool GetEnabled(Control
 control)
            {
                return ((TableProviderWebPart)control).ConnectionPointEnabled;
            }
            
        }
    }
}

OnPreRender メソッドで、コンシューマTableProviderWebPartGetTableData呼び出し、その GetTableData メソッドテーブル データと共に呼び出すデリゲートとして渡すコード例次に示します

Imports System
Imports System.ComponentModel
Imports System.Reflection
Imports System.Collections
Imports System.Data
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts

Namespace Samples.AspNet.VB.Controls

    Public Class TableConsumerWebPart
        Inherits WebPart

        Private _provider As IWebPartTable
        Private _tableData As ICollection

        Private Sub GetTableData(ByVal
 tableData As ICollection)
            _tableData = CType(tableData, ICollection)

        End Sub 'GetTableValue

        Protected Overrides Sub
 OnPreRender(ByVal e As EventArgs)
            If Not (_provider Is
 Nothing) Then
                _provider.GetTableData((New TableCallback(AddressOf
 GetTableData)))
            End If
            'MyBase.OnPreRender(e)

        End Sub 'OnPreRender

        Protected Overrides Sub
 RenderContents(ByVal writer As HtmlTextWriter)

            If Not (_provider Is
 Nothing) Then
                Dim props As PropertyDescriptorCollection
 = _provider.Schema
                Dim count As Integer
 = 0

                If Not (props Is
 Nothing) AndAlso props.Count > 0 _
                  AndAlso Not (_tableData Is
 Nothing) Then
                    For Each prop As
 PropertyDescriptor In props
                        For Each o As
 DataRow In _tableData
                            writer.Write(prop.DisplayName & ":
 " & o(count).ToString())
                        Next
                        writer.WriteBreak()
                        writer.WriteLine()
                        count = count + 1
                    Next
                Else
                    writer.Write("No data")
                End If
            Else
                writer.Write("Not connected")
            End If

        End Sub 'RenderContents

        <ConnectionConsumer("Table")> _
        Public Sub SetConnectionInterface(ByVal
 provider As IWebPartTable)
            _provider = provider

        End Sub 'SetConnectionInterface

        Private Class TableConsumerConnectionPoint
            Inherits ConsumerConnectionPoint

            Public Sub New(ByVal
 callbackMethod As MethodInfo, _
              ByVal interfaceType As Type,
 ByVal controlType As Type, _
              ByVal name As String,
 ByVal id As String, _
              ByVal allowsMultipleConnections As
 Boolean)
                MyBase.New(callbackMethod, interfaceType, controlType,
 _
                  name, id, allowsMultipleConnections)

            End Sub 'New
        End Class 'TableConsumerConnectionPoint
 
    End Class 'TableConsumerWebPart

End Namespace
namespace Samples.AspNet.CS.Controls
{
    using System;
    using System.ComponentModel;
    using System.Data;
    using System.Data.SqlClient;
    using System.Reflection;
    using System.Web.UI;
    using System.Web.UI.WebControls;
    using System.Web.UI.WebControls.WebParts;
    using System.Collections;

    
    public class TableConsumer : WebPart
    {
        private IWebPartTable _provider;
        private ICollection _tableData;

        private void GetTableData(object tableData)
        {
            _tableData = (ICollection)tableData;
        }

        protected override void OnPreRender(EventArgs
 e)
        {
            if (_provider != null)
            {
                _provider.GetTableData(new TableCallback(GetTableData));
            }
        }

        protected override void RenderContents(HtmlTextWriter
 writer)
        {
            if (_provider != null)
            {
                PropertyDescriptorCollection props = _provider.Schema;
                int count = 0;
                if (props != null &&
 props.Count > 0 && _tableData != null)
                {
                    foreach (PropertyDescriptor prop in
 props)
                    {
                        foreach (DataRow o in
 _tableData)
                        {
                            writer.Write(prop.DisplayName + ": " + o[count]);
                        }
                        writer.WriteBreak();
                        writer.WriteLine();
                        count = count + 1;
                    }
                }
                else
                {
                    writer.Write("No data");
                }
            }
            else
            {
                writer.Write("Not connected");
            }
        }

        [ConnectionConsumer("Table")]
        public void SetConnectionInterface(IWebPartTable
 provider)
        {
            _provider = provider;
        }
    }
}

Web ページ2 つコントロール接続含まれている例を次に示します

<%@ Page Language="VB" %>
<%@ Register tagprefix=wp Namespace=Samples.AspNet.VB.Controls
  %>

<script runat="server">

</script>
<html>
<head id="Head1" runat="server">
    <title>ITable Test Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <!-- A static or dynamic connection
 is required to 
             link two Web Parts controls. --->
        <asp:webpartmanager id="WebPartManager1"
 runat="server">
            <StaticConnections>
                <asp:WebPartConnection id=wp1 ProviderID=provider1 
                   ConsumerID=consumer1>
                </asp:WebPartConnection>
            </StaticConnections>
        </asp:webpartmanager>
        <asp:webpartzone id="WebPartZone1" runat="server">
            <zoneTemplate>
            <!-- The following two lines define the two 
                 connected controls. --->
            <wp:TableProviderWebPart ID=provider1 runat=Server 
               title="Web Parts Table Provider Control"
 />
            <wp:TableConsumerWebPart ID=consumer1 runat=Server 
               title="Web Parts Table Consumer Control"/>
            </zoneTemplate>
        </asp:webpartzone>
    </div>
    </form>
</body>
</html>
<%@ page language="C#" %>
<%@ Register tagprefix=wp Namespace=Samples.AspNet.CS.Controls  %>

<script runat="server">

</script>
<html>
<head id="Head1" runat="server">
    <title>ITable Test Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <!-- A static or dynamic connection is required to
 link two
             Web Parts controls. --->
        <asp:webpartmanager id="WebPartManager1" runat="server">
            <StaticConnections>
                <asp:WebPartConnection id=wp1 ProviderID=provider1 
                   ConsumerID=consumer1>
                </asp:WebPartConnection>
            </StaticConnections>
        </asp:webpartmanager>
        <asp:webpartzone id="WebPartZone1" runat="server">
            <zoneTemplate>
            <!-- The following two lines define the 
              two connected controls. --->
            <wp:TableProviderWebPart ID=provider1 runat=Server 
               title="Web Parts Table Provider Control" />
            <wp:TableConsumer ID=consumer1 runat=Server 
               title="Web Parts Table Consumer Control"/>
            </zoneTemplate>
        </asp:webpartzone>
    </div>
    </form>
</body>
</html>
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参照参照
関連項目
System.Web.UI.WebControls.WebParts 名前空間



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