GridView.SelectedIndexChanging Událost
Definice
Důležité
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Nastane při kliknutí na tlačítko Vybrat řádku, ale před GridView ovládacím úchytem operace výběru.
public:
event System::Web::UI::WebControls::GridViewSelectEventHandler ^ SelectedIndexChanging;public event System.Web.UI.WebControls.GridViewSelectEventHandler SelectedIndexChanging;member this.SelectedIndexChanging : System.Web.UI.WebControls.GridViewSelectEventHandler Public Custom Event SelectedIndexChanging As GridViewSelectEventHandler Event Type
Příklady
Následující příklad ukazuje, jak pomocí SelectedIndexChanging události zrušit operaci výběru.
<%@ 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 CustomersGridView_SelectedIndexChanged(Object sender, EventArgs e)
{
// Get the currently selected row using the SelectedRow property.
GridViewRow row = CustomersGridView.SelectedRow;
// Display the first name from the selected row.
// In this example, the third column (index 2) contains
// the first name.
MessageLabel.Text = "You selected " + row.Cells[2].Text + ".";
}
void CustomersGridView_SelectedIndexChanging(Object sender, GridViewSelectEventArgs e)
{
// Get the currently selected row. Because the SelectedIndexChanging event
// occurs before the select operation in the GridView control, the
// SelectedRow property cannot be used. Instead, use the Rows collection
// and the NewSelectedIndex property of the e argument passed to this
// event handler.
GridViewRow row = CustomersGridView.Rows[e.NewSelectedIndex];
// You can cancel the select operation by using the Cancel
// property. For this example, if the user selects a customer with
// the ID "ANATR", the select operation is canceled and an error message
// is displayed.
if (row.Cells[1].Text == "ANATR")
{
e.Cancel = true;
MessageLabel.Text = "You cannot select " + row.Cells[2].Text + ".";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridView Select Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridView Select Example</h3>
<asp:gridview id="CustomersGridView"
datasourceid="CustomersSource"
autogeneratecolumns="False"
autogenerateselectbutton="True"
selectedindex="1"
onselectedindexchanged="CustomersGridView_SelectedIndexChanged"
onselectedindexchanging="CustomersGridView_SelectedIndexChanging"
runat="server" DataKeyNames="CustomerID">
<Columns>
<asp:BoundField DataField="CustomerID"
HeaderText="CustomerID"
InsertVisible="False" ReadOnly="True"
SortExpression="CustomerID" />
<asp:BoundField DataField="FirstName"
HeaderText="FirstName"
SortExpression="FirstName" />
<asp:BoundField DataField="MiddleName"
HeaderText="MiddleName"
SortExpression="MiddleName" />
<asp:BoundField DataField="LastName"
HeaderText="LastName"
SortExpression="LastName" />
<asp:BoundField DataField="Phone"
HeaderText="Phone"
SortExpression="Phone" />
</Columns>
<selectedrowstyle backcolor="LightCyan"
forecolor="DarkBlue"
font-bold="true"/>
</asp:gridview>
<br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:sqldatasource id="CustomersSource"
selectcommand="SELECT CustomerID, FirstName, MiddleName, LastName, Phone FROM SalesLT.Customer"
connectionstring="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>"
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 CustomersGridView_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
' Get the currently selected row using the SelectedRow property.
Dim row As GridViewRow = CustomersGridView.SelectedRow
' Display the first name from the selected row.
' In this example, the third column (index 2) contains
' the first name.
MessageLabel.Text = "You selected " & row.Cells(2).Text & "."
End Sub
Sub CustomersGridView_SelectedIndexChanging(ByVal sender As Object, ByVal e As GridViewSelectEventArgs)
' Get the currently selected row. Because the SelectedIndexChanging event
' occurs before the select operation in the GridView control, the
' SelectedRow property cannot be used. Instead, use the Rows collection
' and the NewSelectedIndex property of the e argument passed to this
' event handler.
Dim row As GridViewRow = CustomersGridView.Rows(e.NewSelectedIndex)
' You can cancel the select operation by using the Cancel
' property. For this example, if the user selects a customer with
' the ID "ANATR", the select operation is canceled and an error message
' is displayed.
If row.Cells(1).Text = "ANATR" Then
e.Cancel = True
MessageLabel.Text = "You cannot select " + row.Cells(2).Text & "."
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridView Select Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridView Select Example</h3>
<asp:gridview id="CustomersGridView"
datasourceid="CustomersSource"
autogeneratecolumns="False"
autogenerateselectbutton="True"
selectedindex="1"
onselectedindexchanged="CustomersGridView_SelectedIndexChanged"
onselectedindexchanging="CustomersGridView_SelectedIndexChanging"
runat="server" DataKeyNames="CustomerID">
<Columns>
<asp:BoundField DataField="CustomerID"
HeaderText="CustomerID"
InsertVisible="False" ReadOnly="True"
SortExpression="CustomerID" />
<asp:BoundField DataField="FirstName"
HeaderText="FirstName"
SortExpression="FirstName" />
<asp:BoundField DataField="MiddleName"
HeaderText="MiddleName"
SortExpression="MiddleName" />
<asp:BoundField DataField="LastName"
HeaderText="LastName"
SortExpression="LastName" />
<asp:BoundField DataField="Phone"
HeaderText="Phone"
SortExpression="Phone" />
</Columns>
<selectedrowstyle backcolor="LightCyan"
forecolor="DarkBlue"
font-bold="true"/>
</asp:gridview>
<br/>
<asp:label id="MessageLabel"
forecolor="Red"
runat="server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:sqldatasource id="CustomersSource"
selectcommand="SELECT CustomerID, FirstName, MiddleName, LastName, Phone FROM SalesLT.Customer"
connectionstring="<%$ ConnectionStrings:AdventureWorksLTConnectionString %>"
runat="server"/>
</form>
</body>
</html>
Poznámky
Událost SelectedIndexChanging se vyvolá po kliknutí na tlačítko Vybrat řádek, ale před ovládacím GridView prvku zpracuje operaci výběru. Díky tomu můžete zadat metodu zpracování událostí, která provádí vlastní rutinu, například zrušení operace výběru, kdykoli dojde k této události.
Poznámka:
Tato událost není vyvolána při programovém SelectedIndex nastavení vlastnosti.
GridViewSelectEventArgs Objekt se předá metodě zpracování událostí, která umožňuje určit index řádku vybraného uživatelem a označit, že operace výběru by měla být zrušena. Chcete-li zrušit operaci výběru, nastavte Cancel vlastnost objektu GridViewSelectEventArgs na true.
Další informace o zpracování událostí naleznete v tématu Zpracování a vyvolávání událostí.
