Freigeben über

DataKeyArray.Count Eigenschaft

  • Referenz

Definition

Namespace:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Ruft die Anzahl der Elemente in der Auflistung ab.

public:
 property int Count { int get(); };
public int Count { get; }
member this.Count : int
Public ReadOnly Property Count As Integer

Eigenschaftswert

Int32

Die Anzahl der Elemente in der Auflistung.

Implementiert

Count

Beispiele

Im folgenden Codebeispiel wird veranschaulicht, wie die Count Eigenschaft verwendet wird, um zu bestimmen, ob eine DataKeyArray Auflistung leer ist.


<%@ 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 CustomerGridView_DataBound(Object sender, EventArgs e)
  {

    // Use the Count property to determine whether the
    // DataKeys collection contains any items.
    if (CustomerGridView.DataKeys.Count > 0)
    {

      MessageLabel.Text = "The primary key of each record displayed are: <br/><br/>";

      // Use the GetEnumerator method to create an enumerator that 
      // contains the DataKey objects for the GridView control.
      IEnumerator keyEnumerator = CustomerGridView.DataKeys.GetEnumerator();

      // Iterate though the enumerator and display the primary key
      // value of each record displayed.
      while (keyEnumerator.MoveNext())
      {
        DataKey key = (DataKey)keyEnumerator.Current;
        MessageLabel.Text += key.Value.ToString() + "<br/>";
      }

    }
    else
    {
      MessageLabel.Text = "No DataKey objects.";
    }

  }
  
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >

  <head runat="server">
    <title>DataKeyArray Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>DataKeyArray Example</h3>
                       
        <asp:gridview id="CustomerGridView"
          datasourceid="CustomerDataSource"
          autogeneratecolumns="true"
          datakeynames="CustomerID"  
          allowpaging="true"
          ondatabound="CustomerGridView_DataBound" 
          runat="server">
            
        </asp:gridview>
        
        <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="CustomerDataSource"
          selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
          connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
          runat="server"/>
            
      </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 CustomerGridView_DataBound(ByVal sender As Object, ByVal e As EventArgs) Handles CustomerGridView.DataBound

    ' Use the Count property to determine whether the
    ' DataKeys collection contains any items.
    If CustomerGridView.DataKeys.Count > 0 Then

      MessageLabel.Text = "The primary key of each record displayed are: <br/><br/>"

      ' Use the GetEnumerator method to create an enumerator that 
      ' contains the DataKey objects for the GridView control.
      Dim keyEnumerator As IEnumerator = CustomerGridView.DataKeys.GetEnumerator()

      ' Iterate though the enumerator and display the primary key
      ' value of each record displayed.
      While keyEnumerator.MoveNext()
      
        Dim key As DataKey = CType(keyEnumerator.Current, DataKey)
        MessageLabel.Text &= key.Value.ToString() & "<br/>"
      
      End While

    Else
    
      MessageLabel.Text = "No DataKey objects."
    
    End If

  End Sub
  
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >

  <head runat="server">
    <title>DataKeyArray Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>DataKeyArray Example</h3>
                       
        <asp:gridview id="CustomerGridView"
          datasourceid="CustomerDataSource"
          autogeneratecolumns="true"
          datakeynames="CustomerID"  
          allowpaging="true"
          runat="server">
            
        </asp:gridview>
        
        <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="CustomerDataSource"
          selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
          connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>" 
          runat="server"/>
            
      </form>
  </body>
</html>

Hinweise

Verwenden Sie die Count Eigenschaft, um die Anzahl der Elemente in der Auflistung zu ermitteln. Die Count Eigenschaft wird häufig verwendet, wenn sie durch die Auflistung durchlaufen wird, um die obere Grenze zu bestimmen. Die Count Eigenschaft wird auch häufig verwendet, um zu bestimmen, ob eine Auflistung leer ist.

Gilt für

Siehe auch