DataKeyArray.Count Proprietà

Riferimento

Definizione

Spazio dei nomi:: System.Web.UI.WebControls

Assembly:: System.Web.dll

Importante

Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.

Ottiene il numero di elementi nella raccolta.

public:
 property int Count { int get(); };

public int Count { get; }

member this.Count : int

Public ReadOnly Property Count As Integer

Valore della proprietà

Int32

Numero di elementi nella raccolta.

Implementazioni

Count

Esempio

Nell'esempio di codice seguente viene illustrato come usare la Count proprietà per determinare se una DataKeyArray raccolta è vuota.


<%@ 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>

Commenti

Utilizzare la Count proprietà per determinare il numero di elementi nella raccolta. La Count proprietà viene comunemente usata durante l'iterazione tramite la raccolta per determinare il relativo limite superiore. La Count proprietà viene comunemente usata anche per determinare se una raccolta è vuota.

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