ButtonField コンストラクタとは何？わかりやすく解説 Weblio辞書

メモ
データバインドコントロールには動的にフィールドを追加できますが、フィールドは静的に宣言しておき、適宜、表示または非表示にすることをお勧めします。フィールドをすべて静的に宣言すると、親データバインドコントロールのビューステートのサイズを削減できます。

使用例

M:System.Web.UI.WebControls.ButtonField.#ctor コンストラクタを使用して、ButtonField オブジェクトを GridView コントロールに動的に追加する方法を次のコード例に示します。

Visual Basic

<%@ Page language="VB" %>

<script runat="server">

    Sub CustomersGridView_RowCommand(ByVal
 sender As Object, ByVal
 e As GridViewCommandEventArgs)
  
        ' If multiple ButtonField column fields are used, use the
        ' CommandName property to determine which button was clicked.
        If e.CommandName = "Select"
 Then
    
            ' Convert the row index stored in the CommandArgument
            ' property to an Integer.
            Dim index As Integer
 = Convert.ToInt32(e.CommandArgument)
    
            ' Get the last name of the selected Customer from the appropriate
            ' cell in the GridView control.
            Dim selectedRow As GridViewRow
 = CustomersGridView.Rows(index)
            Dim contactNameCell As TableCell
 = selectedRow.Cells(1)
            Dim contactName As String
 = contactNameCell.Text
    
            ' Display the selected Customer.
            Message.Text = "You selected " & contactName
 & "."
      
        End If
    
    End Sub

    Sub Page_Load(ByVal sender As
 Object, ByVal e As EventArgs)
  
        ' The field columns need to be created only the first time
        ' the page is loaded.
        If Not IsPostBack Then
      
            ' Dynamically create field columns to display the desired
            ' fields from the data source.
      
            ' Create a ButtonField object to allow the user to 
            ' select an Customer.
            Dim selectButtonField As New
 ButtonField

            selectButtonField.ButtonType = ButtonType.Button
            selectButtonField.CommandName = "Select"
            selectButtonField.HeaderText = "Select Customer"
            selectButtonField.Text = "Select"

            ' Create a BoundField object to display an Customer's last
 name.
            Dim contactNameBoundField As New
 BoundField

            contactNameBoundField.DataField = "ContactName"
            contactNameBoundField.HeaderText = "Contact Name"

            ' Create a BoundField object to display an Customer's first
 name.
            Dim contactTitleBoundField As New
 BoundField

            contactTitleBoundField.DataField = "ContactTitle"
            contactTitleBoundField.HeaderText = "Contact Title"

            ' Add the field columns to the Columns collection of the
            ' GridView control.
            CustomersGridView.Columns.Add(selectButtonField)
            CustomersGridView.Columns.Add(contactNameBoundField)
            CustomersGridView.Columns.Add(contactTitleBoundField)
      
        End If
    
    End Sub

</script>

<html>
  <body>
    <form id="Form1" runat="server">
        
      <h3>ButtonField Constructor Example</h3>

      <asp:label id="Message"
        forecolor="Red"
        runat="server"/>

      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="False"
        onrowcommand="CustomersGridView_RowCommand"
        runat="server">                
      </asp:gridview>
            
        <!-- This example uses Microsoft SQL Server and connects
 -->
        <!-- to the Northwind sample database.            
       -->
        <asp:sqldatasource id="CustomersSqlDataSource"
  
          selectcommand="Select [CustomerID], [CompanyName], [ContactName],
 [ContactTitle] From [Customers]"
          connectionstring="<%$ ConnectionStrings:NorthWindConnection%>"
          runat="server">
        </asp:sqldatasource>
            
    </form>
  </body>
</html>

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

<script runat="server">

  void CustomersGridView_RowCommand(Object sender, GridViewCommandEventArgs
 e)
  {
  
    // If multiple ButtonField column fields are used, use the
    // CommandName property to determine which button was clicked.
    if(e.CommandName=="Select")
    {
    
      // Convert the row index stored in the CommandArgument
      // property to an Integer.
      int index = Convert.ToInt32(e.CommandArgument);    
    
      // Get the last name of the selected Customer from the appropriate
      // cell in the GridView control.
      GridViewRow selectedRow = CustomersGridView.Rows[index];
      TableCell contactCell = selectedRow.Cells[1];
      string contact = contactCell.Text;  
    
      // Display the selected Customer.
      Message.Text = "You selected " + contact + ".";
      
    }
    
  }

  void Page_Load(Object sender, EventArgs e)
  {
  
    // The field columns need to be created only the first time
    // the page is loaded.
    if (!IsPostBack)
    {
      
      // Dynamically create field columns to display the desired
      // fields from the data source.
      
      // Create a ButtonField object to allow the user to 
      // select an Customer.
      ButtonField selectButtonField = new ButtonField ();

      selectButtonField.ButtonType = ButtonType.Button;
      selectButtonField.CommandName = "Select";
      selectButtonField.HeaderText = "Select Customer";
      selectButtonField.Text = "Select";

      // Create a BoundField object to display an Customer's last name.
      BoundField contactNameBoundField = new BoundField();

      contactNameBoundField.DataField = "ContactName";
      contactNameBoundField.HeaderText = "Contact Name";

      // Create a BoundField object to display an Customer's first name.
      BoundField contactTitleBoundField = new BoundField();

      contactTitleBoundField.DataField = "ContactTitle";
      contactTitleBoundField.HeaderText = "Contact Title";

      // Add the field columns to the Columns collection of the
      // GridView control.
      CustomersGridView.Columns.Add (selectButtonField);
      CustomersGridView.Columns.Add(contactNameBoundField);
      CustomersGridView.Columns.Add(contactTitleBoundField);
      
    }
    
  }

</script>

<html>
  <body>
    <form runat="server">
        
      <h3>ButtonField Constructor Example</h3>

      <asp:label id="Message"
        forecolor="Red"
        runat="server"/>

      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="False"
        onrowcommand="CustomersGridView_RowCommand"
        runat="server">                
      </asp:gridview>
            
        <!-- This example uses Microsoft SQL Server and connects -->
        <!-- to the Northwind sample database.                   -->
        <asp:sqldatasource id="CustomersSqlDataSource"  
          selectcommand="Select [CustomerID], [CompanyName], [ContactName],
 [ContactTitle] From [Customers]"
          connectionstring="<%$ ConnectionStrings:NorthWindConnection%>"
          runat="server">
        </asp:sqldatasource>
            
    </form>
  </body>
</html>