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CommandField Конструктор

  • Ссылка

Определение

Пространство имен:
System.Web.UI.WebControls
Сборка:
System.Web.dll

Инициализирует новый экземпляр класса CommandField.

public:
 CommandField();
public CommandField ();
Public Sub New ()

Примеры

В следующем примере кода показано, как использовать конструктор для динамического CommandField добавления столбца поля в GridView элемент управления.


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

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  void Page_Load(Object sender, EventArgs e)
  {
    // Dynamically generated field columns need to be created only 
    // the first time the page is loaded.
    if (!IsPostBack)
    {
      // Create a CommandField object to display a Select button
      // for each record in the GridView control.
      CommandField selectCommandField = new CommandField();
      selectCommandField.ShowSelectButton = true;
      selectCommandField.SelectText = "Select Company"; 
      
      // Create a BoundField object to display the company names.
      BoundField lastNameBoundField = new BoundField();
      lastNameBoundField.DataField = "au_lname";
      lastNameBoundField.HeaderText = "Last Name";

      // Create a BoundField object to display a customer's company name.
      BoundField nameBoundField = new BoundField();
      nameBoundField.DataField = "CompanyName";
      nameBoundField.HeaderText = "Company Name";

      // Create a BoundField object to display a customer's city.
      BoundField cityBoundField = new BoundField();
      cityBoundField.DataField = "City";
      cityBoundField.HeaderText = "City";

      // Add the field columns to the ColumnFields collection of the
      // GridView control.
      CustomersGridView.Columns.Add(selectCommandField);
      CustomersGridView.Columns.Add(nameBoundField);
      CustomersGridView.Columns.Add(cityBoundField);
    }
  }

  void CustomersGridView_SelectedIndexChanged(Object sender, EventArgs e)
  {
    // Get the value of the company name and city from the appropriate cells.
    String companyName = CustomersGridView.SelectedRow.Cells[1].Text;
    String city = CustomersGridView.SelectedRow.Cells[2].Text;
   
    Message.Text = "You selected " + companyName + " located in " + city + ".";
  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>CommandField Constructor Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>CommandField Constructor Example</h3>

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

      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="False"
        onselectedindexchanged="CustomersGridView_SelectedIndexChanged" 
        runat="server">                
      </asp:gridview>
            
      <!-- 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="CustomersSqlDataSource"  
        selectcommand="Select [CustomerID], [CompanyName], [City] From [Customers]"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
        runat="server">
      </asp:sqldatasource>
            
    </form>
  </body>
</html>


<%@ Page language="VB" AutoEventWireup="False" %>  

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load

    ' Dynamically generated field columns need to be created only 
    ' the first time the page is loaded.
    If Not IsPostBack Then
    
      ' Create a CommandField object to display a Select button
      ' for each record in the GridView control.
      Dim selectCommandField As New CommandField()
      selectCommandField.ShowSelectButton = True
      selectCommandField.SelectText = "Select Company"
      
      ' Create a BoundField object to display the company names.
      Dim lastNameBoundField As New BoundField()
      lastNameBoundField.DataField = "au_lname"
      lastNameBoundField.HeaderText = "Last Name"

      ' Create a BoundField object to display a customer's company name.
      Dim nameBoundField As New BoundField()
      nameBoundField.DataField = "CompanyName"
      nameBoundField.HeaderText = "Company Name"

      ' Create a BoundField object to display a customer's city.
      Dim cityBoundField As New BoundField()
      cityBoundField.DataField = "City"
      cityBoundField.HeaderText = "City"

      ' Add the field columns to the ColumnFields collection of the
      ' GridView control.
      CustomersGridView.Columns.Add(selectCommandField)
      CustomersGridView.Columns.Add(nameBoundField)
      CustomersGridView.Columns.Add(cityBoundField)
      
    End If
      
  End Sub

  Sub CustomersGridView_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles CustomersGridView.SelectedIndexChanged
    
    ' Get the value of the company name and city from the appropriate cells.
    Dim companyName As String = CustomersGridView.SelectedRow.Cells(1).Text
    Dim city As String = CustomersGridView.SelectedRow.Cells(2).Text
   
    Message.Text = "You selected " & companyName & " located in " & city & "."
    
  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>CommandField Constructor Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>CommandField Constructor Example</h3>

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

      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="False"
        runat="server">                
      </asp:gridview>
            
      <!-- 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="CustomersSqlDataSource"  
        selectcommand="Select [CustomerID], [CompanyName], [City] From [Customers]"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
        runat="server">
      </asp:sqldatasource>
            
    </form>
  </body>
</html>

Комментарии

Используйте этот конструктор для инициализации нового экземпляра CommandField класса. Этот конструктор обычно используется при добавлении полей в динамически созданный элемент управления с привязкой к данным.

Чтобы динамически добавить CommandField поле в элемент управления с привязкой к данным, создайте новый CommandField объект, задайте его свойства и добавьте его в коллекцию полей элемента управления с привязкой к данным. Например, если вы используете GridView элемент управления, добавьте CommandField объект в коллекцию Columns .

Примечание

Хотя вы можете динамически добавлять поля в элемент управления с привязкой к данным, настоятельно рекомендуется, чтобы поля были статически объявлены, а затем показаны или скрыты. Статически объявляя все поля, уменьшает размер состояния представления для родительского элемента управления с привязкой к данным.

Применяется к

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