DataKeyArray.Count Eigenschap
Definitie
Belangrijk
Bepaalde informatie heeft betrekking op een voorlopige productversie die aanzienlijk kan worden gewijzigd voordat deze wordt uitgebracht. Microsoft biedt geen enkele expliciete of impliciete garanties met betrekking tot de informatie die hier wordt verstrekt.
Hiermee haalt u het aantal items in de verzameling op.
public:
property int Count { int get(); };public int Count { get; }member this.Count : intPublic ReadOnly Property Count As IntegerWaarde van eigenschap
Het aantal items in de verzameling.
Implementeringen
Voorbeelden
In het volgende codevoorbeeld ziet u hoe u de Count eigenschap gebruikt om te bepalen of een DataKeyArray verzameling leeg is.
<%@ 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>
Opmerkingen
Gebruik de Count eigenschap om het aantal items in de verzameling te bepalen. De Count eigenschap wordt vaak gebruikt bij het doorlopen van de verzameling om de bovengrens ervan te bepalen. De Count eigenschap wordt ook vaak gebruikt om te bepalen of een verzameling leeg is.
