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

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.NET Framework クラスライブラリリファレンス

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GridViewSelectEventHandler 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。

GridView コントロールの SelectedIndexChanging 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 GridViewSelectEventHandler
 ( _
    sender As Object, _
    e As GridViewSelectEventArgs _
)

Visual Basic (使用法)

Dim instance As New GridViewSelectEventHandler(AddressOf
 HandlerMethod)

public delegate void GridViewSelectEventHandler
 (
    Object sender,
    GridViewSelectEventArgs e
)

C++

public delegate void GridViewSelectEventHandler
 (
    Object^ sender, 
    GridViewSelectEventArgs^ e
)

/** @delegate */
public delegate void GridViewSelectEventHandler
 (
    Object sender, 
    GridViewSelectEventArgs 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 GridViewSelectEventArgs オブジェクト。

解説

SelectedIndexChanging イベントは、Select ボタン (CommandName プロパティが "Select" に設定されているボタン) がクリックされた場合に、GridView コントロールが選択操作を処理する前に発生します。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 (選択操作のキャンセルなど) を実行するイベント処理メソッドを提供できます。

GridViewSelectEventHandler 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

GridViewSelectEventHandler デリゲートを、プログラムによって GridView コントロールの SelectedIndexChanging イベントに追加する方法を次の例に示します。

Visual Basic

<%@ Page language="VB" %>

<script runat="server">

    Sub Page_Load(ByVal sender As
 Object, ByVal e As EventArgs)
        
        ' Create a new GridView object.
        Dim authorGridView As GridView = New
 GridView
         
        ' Set the GridView object's properties.
        authorGridView.ID = "AuthorGridView"
        authorGridView.DataSourceID = "AuthorsSqlDataSource"
        authorGridView.AutoGenerateColumns = True
        authorGridView.AutoGenerateSelectButton = True
        authorGridView.AllowPaging = True
        authorGridView.SelectedIndex = 1
        authorGridView.SelectedRowStyle.BackColor = System.Drawing.Color.LightCyan
        authorGridView.SelectedRowStyle.ForeColor = System.Drawing.Color.DarkBlue
        authorGridView.SelectedRowStyle.Font.Bold = True
        
        ' Programmatically register the event-handling methods.
        AddHandler authorGridView.SelectedIndexChanged, AddressOf
 AuthorsGridView_SelectedIndexChanged
        AddHandler authorGridView.SelectedIndexChanging, AddressOf
 AuthorsGridView_SelectedIndexChanging
        
        ' Add the GridView object to the Controls collection
        ' of the PlaceHolder control.
        GridViewPlaceHolder.Controls.Add(authorGridView)
        
    End Sub
    
    Sub AuthorsGridView_SelectedIndexChanged(ByVal
 sender As Object, ByVal
 e As EventArgs)

        ' Get the currently selected row using the SelectedRow property.
        Dim AuthorsGridView As GridView = CType(sender,
 GridView)
        Dim row As GridViewRow = AuthorsGridView.SelectedRow
        
        ' Display the author's name from the selected row.
        ' In this example, the second and third columns contain
        ' the author's last and first name, respectively.
        Message.Text = "You selected " & row.Cells(2).Text
 & _
            " " & row.Cells(1).Text & "."
    
    End Sub
    
    Sub AuthorsGridView_SelectedIndexChanging(ByVal
 sender As Object, ByVal
 e As GridViewSelectEventArgs)
        
        ' Get the currently selected row. Because the SelectedIndexChanging
 event
        ' occurs before the select operation in the GridView control,
 the
        ' SelectedRow property cannot be used. Instead, use the Rows
 collection
        ' and the NewSelectedIndex property of the e argument passed
 to this 
        ' event handler.
        Dim AuthorsGridView As GridView = CType(sender,
 GridView)
        Dim row As GridViewRow = AuthorsGridView.Rows(e.NewSelectedIndex)
        
        ' If the user selects an author with the last name White,
        ' cancel the selection operation and display an error message.
        If row.Cells(1).Text = "White"
        
            e.Cancel = true
            Message.Text = "You cannot select " &
 row.Cells(2).Text & _
            " " & row.Cells(1).Text & "."
        
        End If
    
    End Sub

</script>

<html>
    <body>
        <form runat="server">
        
            <h3>GridViewSelectEventHandler Example</h3>
            
            <asp:placeholder id="GridViewPlaceHolder"
                runat="Server"/>
            
            <!-- This example uses Microsoft SQL Server and
 connects -->
            <!-- to the Pubs sample database.             
            -->
            <asp:sqldatasource id="AuthorsSqlDataSource"
  
                selectcommand="SELECT [au_lname], [au_fname],
 [address], [city], [state], [zip], [contract] FROM [authors]"
                connectionstring="server=localhost;database=pubs;integrated
 security=SSPI"
                runat="server">
            </asp:sqldatasource>
            
            <br/>
            
            <asp:label id="Message"
                runat="server"/>
            
        </form>
    </body>
</html>

<%@ Page language="C#" %>

<script runat="server">

    void Page_Load(Object sender, EventArgs e)
    {
        
        // Create a new GridView object.
        GridView authorGridView = new GridView();
         
        // Set the GridView object's properties.
        authorGridView.ID = "AuthorGridView";
        authorGridView.DataSourceID = "AuthorsSqlDataSource"; 
        authorGridView.AutoGenerateColumns = true;
        authorGridView.AutoGenerateSelectButton = true;
        authorGridView.AllowPaging = true; 
        authorGridView.SelectedIndex = 1;
        authorGridView.SelectedRowStyle.BackColor = System.Drawing.Color.LightCyan;
        authorGridView.SelectedRowStyle.ForeColor = System.Drawing.Color.DarkBlue;
        authorGridView.SelectedRowStyle.Font.Bold = true;
        
        // Programmatically register the event-handling methods.
        authorGridView.SelectedIndexChanged += new EventHandler(this.AuthorsGridView_SelectedIndexChanged);
        authorGridView.SelectedIndexChanging += new GridViewSelectEventHandler(this.AuthorsGridView_SelectedIndexChanging);
        
        // Add the GridView object to the Controls collection
        // of the PlaceHolder control.
        GridViewPlaceHolder.Controls.Add(authorGridView);
        
    }
    
    void AuthorsGridView_SelectedIndexChanged(Object sender, EventArgs
 e)
    {
    
        // Get the currently selected row using the SelectedRow property.
        GridView AuthorsGridView = (GridView)sender;
        GridViewRow row = AuthorsGridView.SelectedRow;
        
        // Display the author's name from the selected row.
        // In this example, the second and third columns contain
        // the author's last and first name, respectively.
        Message.Text = "You selected " + row.Cells[2].Text +
            " " + row.Cells[1].Text + ".";
    
    }
    
    void AuthorsGridView_SelectedIndexChanging(Object sender,
 GridViewSelectEventArgs e)
    {
        
        // Get the currently selected row. Because the SelectedIndexChanging
 event
        // occurs before the select operation in the GridView control,
 the
        // SelectedRow property cannot be used. Instead, use the Rows
 collection
        // and the NewSelectedIndex property of the e argument passed
 to this 
        // event handler.
        GridView AuthorsGridView = (GridView)sender;
        GridViewRow row = AuthorsGridView.Rows[e.NewSelectedIndex];
        
        // If the user selects an author with the last name White,
        // cancel the selection operation and display an error message.
        if(row.Cells[1].Text == "White")
        {
        
            e.Cancel = true;
            Message.Text = "You cannot select " + row.Cells[2].Text +
            " " + row.Cells[1].Text + ".";
        
        }
    
    }

</script>

<html>
    <body>
        <form runat="server">
        
            <h3>GridViewSelectEventHandler Example</h3>
            
            <asp:placeholder id="GridViewPlaceHolder"
                runat="Server"/>
            
            <!-- This example uses Microsoft SQL Server and connects -->
            <!-- to the Pubs sample database.                         -->
            <asp:sqldatasource id="AuthorsSqlDataSource"  
                selectcommand="SELECT [au_lname], [au_fname], [address], [city],
 [state], [zip], [contract] FROM [authors]"
                connectionstring="server=localhost;database=pubs;integrated
 security=SSPI"
                runat="server">
            </asp:sqldatasource>
            
            <br/>
            
            <asp:label id="Message"
                runat="server"/>
            
        </form>
    </body>
</html>

GridViewSelectEventHandler デリゲートを、宣言によって GridView コントロールの SelectedIndexChanging イベントに追加する方法を次の例に示します。

Visual Basic

<%@ Page language="VB" %>

<script runat="server">

  Sub CustomersGridView_SelectedIndexChanged(ByVal
 sender As Object, ByVal
 e As EventArgs)
        
    ' Get the currently selected row using the SelectedRow property.
    Dim row As GridViewRow = CustomersGridView.SelectedRow
        
    ' Display the company name from the selected row.
    ' In this example, the third column (index 2) contains
    ' the company name.
    Message.Text = "You selected " & row.Cells(2).Text
 & "."
    
  End Sub

  Sub CustomersGridView_SelectedIndexChanging(ByVal
 sender As Object, ByVal
 e As GridViewSelectEventArgs)
        
    ' Get the currently selected row. Because the SelectedIndexChanging
 event
    ' occurs before the select operation in the GridView control, the
    ' SelectedRow property cannot be used. Instead, use the Rows collection
    ' and the NewSelectedIndex property of the e argument passed to
 this 
    ' event handler.
    Dim row As GridViewRow = CustomersGridView.Rows(e.NewSelectedIndex)

    ' You can cancel the select operation by using the Cancel
    ' property. For this example, if the user selects a customer with
 
    ' the ID "ANATR", the select operation is canceled and
 an error message
    ' is displayed.
    If row.Cells(1).Text = "ANATR"
 Then
 
      e.Cancel = True
      Message.Text = "You cannot select " + row.Cells(2).Text
 & "."
      
    End If
    
  End Sub

</script>

<html>
  <body>
    <form runat="server">
        
     <h3>GridView Select Example</h3>

     <asp:gridview id="CustomersGridView" 
       datasourceid="CustomersSource" 
       autogeneratecolumns="true"
       autogenerateselectbutton="true"
       allowpaging="true" 
       selectedindex="0"
       onselectedindexchanged="CustomersGridView_SelectedIndexChanged"
       onselectedindexchanging="CustomersGridView_SelectedIndexChanging"
   
       runat="server">
                
       <selectedrowstyle backcolor="LightCyan"
         forecolor="DarkBlue"
         font-bold="true"/>  
                
     </asp:gridview>
            
      <br/>
            
      <asp:label id="Message"
        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="CustomersSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address],
 [City], [PostalCode], [Country] From [Customers]"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
 
        runat="server"/>
            
    </form>
  </body>
</html>

<%@ Page language="C#" %>

<script runat="server">

  void CustomersGridView_SelectedIndexChanged(Object sender, EventArgs
 e)
  {
    
    // Get the currently selected row using the SelectedRow property.
    GridViewRow row = CustomersGridView.SelectedRow;
        
    // Display the company name from the selected row.
    // In this example, the third column (index 2) contains
    // the company name.
    Message.Text = "You selected " + row.Cells[2].Text + ".";
    
  }

  void CustomersGridView_SelectedIndexChanging(Object sender,
 GridViewSelectEventArgs e)
  {
        
    // Get the currently selected row. Because the SelectedIndexChanging
 event
    // occurs before the select operation in the GridView control, the
    // SelectedRow property cannot be used. Instead, use the Rows collection
    // and the NewSelectedIndex property of the e argument passed to
 this 
    // event handler.
    GridViewRow row = CustomersGridView.Rows[e.NewSelectedIndex];

    // You can cancel the select operation by using the Cancel
    // property. For this example, if the user selects a customer with
 
    // the ID "ANATR", the select operation is canceled and
 an error message
    // is displayed.
    if (row.Cells[1].Text == "ANATR")
    {
        
      e.Cancel = true;
      Message.Text = "You cannot select " + row.Cells[2].Text + ".";
        
    }
    
  }

</script>

<html>
  <body>
    <form runat="server">
        
     <h3>GridView Select Example</h3>

     <asp:gridview id="CustomersGridView" 
       datasourceid="CustomersSource" 
       autogeneratecolumns="true"
       autogenerateselectbutton="true"
       allowpaging="true" 
       selectedindex="0"
       onselectedindexchanged="CustomersGridView_SelectedIndexChanged"
       onselectedindexchanging="CustomersGridView_SelectedIndexChanging"
   
       runat="server">
                
       <selectedrowstyle backcolor="LightCyan"
         forecolor="DarkBlue"
         font-bold="true"/>  
                
     </asp:gridview>
            
      <br/>
            
      <asp:label id="Message"
        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="CustomersSource"
        selectcommand="Select [CustomerID], [CompanyName], [Address], [City],
 [PostalCode], [Country] From [Customers]"
        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
GridView クラス
GridViewSelectEventArgs クラス
GridView.SelectedIndexChanging イベント
OnSelectedIndexChanging
その他の技術情報
イベントとデリゲート

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

GridViewSelectEventHandler デリゲート

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