CheckBoxField Konstruktor

Definition

Namnområde:
System.Web.UI.WebControls
Sammansättning:
System.Web.dll

Initierar en ny instans av CheckBoxField klassen.

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

Exempel

Följande kodexempel visar hur du använder konstruktorn för att dynamiskt lägga till ett CheckBoxField objekt i en GridView kontroll.


<%@ 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)
  {

    // The columns need to be created only the first time
    // the page is loaded.
    if(!IsPostBack)
    {
  
      // Dynamically create columns to display the desired
      // fields from the data source. Columns that are 
      // dynamically added to the GridView control are not persisted 
      // across posts and must be recreated each time the page is 
      // loaded.
  
      // Create a BoundField object to display an author's last name.
      BoundField lastNameBoundField = new BoundField();
      lastNameBoundField.DataField = "au_lname";
      lastNameBoundField.HeaderText = "Last Name";
    
      // Create a CheckBoxField object to indicate whether the author
      // is on contract.
      CheckBoxField contractCheckBoxField = new CheckBoxField();
      contractCheckBoxField.DataField = "contract";
      contractCheckBoxField.HeaderText = "Contract";
    
      // Add the columns to the Columns collection of the
      // GridView control.
      AuthorsGridView.Columns.Add(lastNameBoundField);
      AuthorsGridView.Columns.Add(contractCheckBoxField);

    }
  
  }

</script>

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

      <asp:gridview id="AuthorsGridView" 
        datasourceid="AuthorsSqlDataSource" 
        autogeneratecolumns="False"
        runat="server">                
      </asp:gridview>
            
      <!-- 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>
            
    </form>
  </body>
</html>


<%@ Page language="VB" %>

<!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(sender as Object, e As EventArgs)
  
    ' The columns need to be created only the first time
    ' the page is loaded.
    If Not IsPostBack Then

      ' Dynamically create columns to display the desired
      ' fields from the data source. Columns that are 
      ' dynamically added to the GridView control are not persisted 
      ' across posts and must be recreated each time the page is 
      ' loaded.
  
      ' Create a BoundField object to display an author's last name.
      Dim lastNameBoundField As BoundField = New BoundField
      lastNameBoundField.DataField = "au_lname"
      lastNameBoundField.HeaderText = "Last Name"
    
      ' Create a CheckBoxField object to indicate whether the author
      ' is on contract.
      Dim contractCheckBoxField As CheckBoxField = New CheckBoxField
      contractCheckBoxField.DataField = "contract"
      contractCheckBoxField.HeaderText = "Contract"
    
      ' Add the columns to the Columns collection of the
      ' GridView control.
      AuthorsGridView.Columns.Add(lastNameBoundField)
      AuthorsGridView.Columns.Add(contractCheckBoxField)

    End If
  
  End Sub

</script>

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

      <asp:gridview id="AuthorsGridView" 
        datasourceid="AuthorsSqlDataSource" 
        autogeneratecolumns="False"
        runat="server">                
      </asp:gridview>
            
      <!-- 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>
            
    </form>
  </body>
</html>

Kommentarer

Använd den här konstruktorn för att initiera en ny instans av CheckBoxField klassen. Den här konstruktorn används ofta när du lägger till fält i en dynamiskt skapad databunden kontroll.

Om du vill lägga till ett CheckBoxField objekt dynamiskt i en databunden kontroll skapar du ett nytt CheckBoxField objekt, anger dess egenskaper och lägger sedan till det i den databundna kontrollens fältsamling. Om du till exempel använder GridView kontrollen lägger du till objektet CheckBoxField i Columns samlingen.

Note

Även om du dynamiskt kan lägga till fält i en databunden kontroll rekommenderar vi starkt att alla fält deklareras statiskt och sedan visas eller döljs efter behov. Om du statiskt deklarerar alla fält minskar storleken på visningstillståndet för den överordnade databundna kontrollen.

Gäller för

Se även