DetailsViewDeleteEventHandler デリゲートとは何？わかりやすく解説 Weblio辞書

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DetailsViewDeleteEventHandler デリゲート

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

DetailsView コントロールの ItemDeleting イベントを処理するメソッドを表します。

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

Visual Basic (宣言)

Public Delegate Sub DetailsViewDeleteEventHandler
 ( _
    sender As Object, _
    e As DetailsViewDeleteEventArgs _
)

Visual Basic (使用法)

Dim instance As New DetailsViewDeleteEventHandler(AddressOf
 HandlerMethod)

public delegate void DetailsViewDeleteEventHandler
 (
    Object sender,
    DetailsViewDeleteEventArgs e
)

C++

public delegate void DetailsViewDeleteEventHandler
 (
    Object^ sender, 
    DetailsViewDeleteEventArgs^ e
)

/** @delegate */
public delegate void DetailsViewDeleteEventHandler
 (
    Object sender, 
    DetailsViewDeleteEventArgs e
)

JScript

JScript では、デリゲートは使用できますが、新規に宣言することはできません。

パラメータ

sender: イベントのソース。

e: イベントデータを格納している DetailsViewDeleteEventArgs。

解説

DetailsView コントロールは、コントロール内の Delete ボタン (CommandName プロパティが "Delete" に設定されたボタン) がクリックされた場合に、DetailsView コントロールが実際にレコードを削除した後に ItemDeleting イベントを発生させます。これにより、このイベントが発生するたびにカスタムルーチン (削除操作の結果を確認するなど) を実行するイベントハンドラを提供できます。

DetailsViewDeleteEventHandler デリゲートを作成する場合は、イベントを処理するメソッドを識別してください。イベントをイベントハンドラに関連付けるには、デリゲートのインスタンスをイベントに追加します。デリゲートを削除しない限り、そのイベントが発生すると常にイベントハンドラが呼び出されます。イベントハンドラデリゲートの詳細については、「イベントとデリゲート」を参照してください。

使用例

DetailsViewDeleteEventHandler デリゲートを、プログラムによって DetailsView コントロールの ItemDeleting イベントに追加する方法のコード例を次に示します。

Visual Basic

<%@ page language="VB"%>
  
<script runat="server">

  Sub Page_Load(ByVal sender As
 Object, ByVal e As EventArgs)
    
    ' Create a new DetailsView object.
    Dim customerDetailsView As New
 DetailsView()
    
    ' Set the DetailsView object's properties.
    customerDetailsView.ID = "CustomerDetailsView"
    customerDetailsView.DataSourceID = "DetailsViewSource"
    customerDetailsView.AutoGenerateRows = True
    customerDetailsView.AutoGenerateDeleteButton = True
    customerDetailsView.AllowPaging = True
    customerDetailsView.PagerSettings.Mode = PagerButtons.NextPrevious
    
    Dim keyArray() As String
 = {"CustomerID"}
    customerDetailsView.DataKeyNames = keyArray
    
    ' Programmatically register the event-handling method
    ' for the ItemDeleting event of a DetailsView control.
    AddHandler customerDetailsView.ItemDeleting, AddressOf
 CustomerDetailsView_ItemDeleting

    ' Add the DetailsView object to the Controls collection
    ' of the PlaceHolder control.
    DetailsViewPlaceHolder.Controls.Add(customerDetailsView)

  End Sub

  Sub CustomerDetailsView_ItemDeleting(ByVal
 sender As Object, ByVal
 e As DetailsViewDeleteEventArgs)

    ' Get customer ID and name from the Keys and Values
    ' properties.
    Dim keyValue As String
 = e.Keys("CustomerID").ToString()
    Dim customerName As String
 = e.Values("CompanyName").ToString()

    ' Cancel the delete operation if the user attempts to 
    ' delete protected record. In this example, records
    ' with a customer ID that starts with with "A" cannot
    ' be deleted.
    If keyValue.StartsWith("A")
 Then

      e.Cancel = True
      MessageLabel.Text = "You cannot delete " &
 _
        customerName & ". This customer is protected."
  
    Else
  
      MessageLabel.Text = "Row " & e.RowIndex.ToString()
 & _
        " deleted."
  
    End If
  
  End Sub

</script>
  
<html>    
  <body>
    <form runat="server">
        
      <h3>DetailsViewDeleteEventHandler Example</h3>
        
        <!-- Use a PlaceHolder control as the container for
 the -->
        <!-- dynamically generated DetailsView control.         -->       
        <asp:PlaceHolder id="DetailsViewPlaceHolder"
          runat="server"/>
          
        <br/><br/>
        
        <asp:label id="MessageLabel"
          forecolor="Red"
          runat="server"/>
            
        <!-- This example uses Microsoft SQL Server and connects
  -->
        <!-- to the Northwind sample database. Use an ASP.NET
     -->
        <!-- expression to retrieve the connection string
 value   -->
        <!-- from the web.config file.                            -->
        <asp:sqldatasource id="DetailsViewSource"
          selectcommand="Select [CustomerID], [CompanyName], [Address], 
            [City], [PostalCode], [Country] From [Customers]"
          deletecommand="Delete [Customers] 
            Where [CustomerID]=@CustomerID"
          connectionstring=
            "<%$ ConnectionStrings:NorthWindConnectionString%>"
 
          runat="server"/>
            
      </form>
  </body>
</html>

<%@ page language="C#"%>
  
<script runat="server">

  void Page_Load(Object sender, EventArgs e)
  {
    
    // Create a new DetailsView object.
    DetailsView customerDetailsView = new DetailsView();
    
    // Set the DetailsView object's properties.
    customerDetailsView.ID = "CustomerDetailsView";
    customerDetailsView.DataSourceID = "DetailsViewSource";
    customerDetailsView.AutoGenerateRows = true;
    customerDetailsView.AutoGenerateDeleteButton = true;
    customerDetailsView.AllowPaging = true;
    customerDetailsView.PagerSettings.Mode = PagerButtons.NextPrevious;
    customerDetailsView.DataKeyNames = new String[1] { "CustomerID"
 };

    // Programmatically register the event-handling method
    // for the ItemDeleting event of a DetailsView control.
    customerDetailsView.ItemDeleting += new DetailsViewDeleteEventHandler(this.CustomerDetailsView_ItemDeleting);

    // Add the DetailsView object to the Controls collection
    // of the PlaceHolder control.
    DetailsViewPlaceHolder.Controls.Add(customerDetailsView);

  }

  void CustomerDetailsView_ItemDeleting(Object sender, DetailsViewDeleteEventArgs
 e)
  {

    // Get customer ID and name from the Keys and Values
    // properties.
    String keyValue = e.Keys["CustomerID"].ToString();
    String customerName = e.Values["CompanyName"].ToString();

    // Cancel the delete operation if the user attempts to 
    // delete protected record. In this example, records
    // with a customer ID that starts with with "A" cannot
    // be deleted.
    if (keyValue.StartsWith("A"))
    {
      e.Cancel = true;
      MessageLabel.Text = "You cannot delete " +
        customerName + ". This customer is protected.";
    }
    else
    {
      MessageLabel.Text = "Row " + e.RowIndex.ToString() +
        " deleted.";
    }

  }

</script>
 
 <html>   
  <body>
    <form runat="server">
        
      <h3>DetailsViewDeleteEventHandler Example</h3>
        
        <!-- Use a PlaceHolder control as the container for
 the -->
        <!-- dynamically generated DetailsView control.         -->       
        <asp:PlaceHolder id="DetailsViewPlaceHolder"
          runat="server"/>
          
        <br/><br/>
        
        <asp:label id="MessageLabel"
          forecolor="Red"
          runat="server"/>
            
        <!-- This example uses Microsoft SQL Server and connects  -->
        <!-- to the Northwind sample database. Use an ASP.NET     -->
        <!-- expression to retrieve the connection string value
   -->
        <!-- from the web.config file.                            -->
        <asp:sqldatasource id="DetailsViewSource"
          selectcommand="Select [CustomerID], [CompanyName], [Address], 
            [City], [PostalCode], [Country] From [Customers]"
          deletecommand="Delete [Customers] 
            Where [CustomerID]=@CustomerID"
          connectionstring=
            "<%$ ConnectionStrings:NorthWindConnectionString%>" 
          runat="server"/>
            
      </form>
  </body>
</html>

DetailsViewDeleteEventHandler デリゲートを、宣言によって DetailsView コントロールの ItemDeleting イベントに追加する方法のコード例を次に示します。

Visual Basic

<%@ page language="VB" autoeventwireup="false"%>
  
<script runat="server">

  Sub CustomerDetailsView_ItemDeleting(ByVal
 sender As Object, _
    ByVal e As DetailsViewDeleteEventArgs)
 _
    Handles CustomerDetailsView.ItemDeleting

    ' Get customer ID and name from the Keys and Values
    ' properties.
    Dim keyValue As String
 = e.Keys("CustomerID").ToString()
    Dim customerName As String
 = e.Values("CompanyName").ToString()

    ' Cancel the delete operation if the user attempts to 
    ' delete protected record. In this example, records
    ' with a customer ID that starts with with "A" cannot
    ' be deleted.
    If keyValue.StartsWith("A")
 Then

      e.Cancel = True
      MessageLabel.Text = "You cannot delete " &
 _
        customerName & ". This customer is protected."
  
    Else
  
      MessageLabel.Text = "Row " & e.RowIndex.ToString()
 & _
        " deleted."
  
    End If
  
  End Sub

</script>
  
<html>    
  <body>
    <form runat="server">
        
      <h3>DetailsViewDeleteEventHandler Example</h3>
        
        <asp:detailsview id="CustomerDetailsView"
          datasourceid="DetailsViewSource"
          autogeneraterows="true"
          autogeneratedeletebutton="true"
          allowpaging="true"
          datakeynames="CustomerID" 
          runat="server">
        
          <pagersettings mode="NextPrevious"/>
        
        </asp:detailsview>
          
        <br/><br/>
        
        <asp:label id="MessageLabel"
          forecolor="Red"
          runat="server"/>
            
        <!-- This example uses Microsoft SQL Server and connects
  -->
        <!-- to the Northwind sample database. Use an ASP.NET
     -->
        <!-- expression to retrieve the connection string
 value   -->
        <!-- from the web.config file.                            -->
        <asp:sqldatasource id="DetailsViewSource"
          selectcommand="Select [CustomerID], [CompanyName], [Address], 
            [City], [PostalCode], [Country] From [Customers]"
          deletecommand="Delete [Customers] 
            Where [CustomerID]=@CustomerID"
          connectionstring=
            "<%$ ConnectionStrings:NorthWindConnectionString%>"
 
          runat="server"/>
            
      </form>
  </body>
</html>

<%@ page language="C#"%>
  
<script runat="server">

  void CustomerDetailsView_ItemDeleting(Object sender, 
    DetailsViewDeleteEventArgs e)
  {

    // Get customer ID and name from the Keys and Values
    // properties.
    String keyValue = e.Keys["CustomerID"].ToString();
    String customerName = e.Values["CompanyName"].ToString();

    // Cancel the delete operation if the user attempts to 
    // delete protected record. In this example, records
    // with a customer ID that starts with with "A" cannot
    // be deleted.
    if (keyValue.StartsWith("A"))
    {
      e.Cancel = true;
      MessageLabel.Text = "You cannot delete " +
        customerName + ". This customer is protected.";
    }
    else
    {
      MessageLabel.Text = "Row " + e.RowIndex.ToString() +
        " deleted.";
    }

  }

</script>
 
 <html>   
  <body>
    <form runat="server">
        
      <h3>DetailsViewDeleteEventHandler Example</h3>
        
        <asp:detailsview id="CustomerDetailsView"
          datasourceid="DetailsViewSource"
          autogeneraterows="true"
          autogeneratedeletebutton="true"
          allowpaging="true"
          datakeynames="CustomerID"
          onitemdeleting="CustomerDetailsView_ItemDeleting"  
          runat="server">
        
          <pagersettings mode="NextPrevious"/>
        
        </asp:detailsview>
          
        <br/><br/>
        
        <asp:label id="MessageLabel"
          forecolor="Red"
          runat="server"/>
            
        <!-- This example uses Microsoft SQL Server and connects  -->
        <!-- to the Northwind sample database. Use an ASP.NET     -->
        <!-- expression to retrieve the connection string value
   -->
        <!-- from the web.config file.                            -->
        <asp:sqldatasource id="DetailsViewSource"
          selectcommand="Select [CustomerID], [CompanyName], [Address], 
            [City], [PostalCode], [Country] From [Customers]"
          deletecommand="Delete [Customers] 
            Where [CustomerID]=@CustomerID"
          connectionstring=
            "<%$ ConnectionStrings:NorthWindConnectionString%>" 
          runat="server"/>
            
      </form>
  </body>
</html>

プラットフォーム

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

開発プラットフォームの中には、.NET Framework によってサポートされていないバージョンがあります。サポートされているバージョンについては、「システム要件」を参照してください。

バージョン情報

.NET Framework
サポート対象 : 2.0

参照

関連項目
System.Web.UI.WebControls 名前空間
DetailsView クラス
DetailsViewDeleteEventArgs クラス
DetailsView.ItemDeleting イベント
OnItemDeleting
その他の技術情報
イベントとデリゲート

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DetailsViewDeleteEventHandler デリゲートとは？ わかりやすく解説

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DetailsViewDeleteEventHandler デリゲートとは？わかりやすく解説