GridViewCommandEventHandler Delegato
Definizione
Importante
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Rappresenta il metodo che gestisce l'evento RowCommand di un controllo GridView.
public delegate void GridViewCommandEventHandler(System::Object ^ sender, GridViewCommandEventArgs ^ e);public delegate void GridViewCommandEventHandler(object sender, GridViewCommandEventArgs e);type GridViewCommandEventHandler = delegate of obj * GridViewCommandEventArgs -> unitPublic Delegate Sub GridViewCommandEventHandler(sender As Object, e As GridViewCommandEventArgs)Parametri
- sender
- Object
Origine dell'evento.
Oggetto GridViewCommandEventArgs contenente i dati dell'evento.
Esempio
Nell'esempio seguente viene illustrato come aggiungere un GridViewCommandEventHandler delegato a livello di codice all'evento RowCommand di un GridView controllo .
<%@ 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)
{
// Create a new GridView object.
GridView customersGridView = new GridView();
// Set the GridView object's properties.
customersGridView.ID = "CustomersGridView";
customersGridView.DataSourceID = "CustomersSource";
customersGridView.AutoGenerateColumns = false;
// Dynamically create the columns for the GridView control.
ButtonField addColumn = new ButtonField();
addColumn.CommandName = "Add";
addColumn.Text = "Add";
addColumn.ButtonType = ButtonType.Link;
BoundField companyNameColumn = new BoundField();
companyNameColumn.DataField = "CompanyName";
companyNameColumn.HeaderText = "Company Name";
BoundField cityColumn = new BoundField();
cityColumn.DataField = "City";
cityColumn.HeaderText = "City";
// Add the columns to the Columns collection
// of the GridView control.
customersGridView.Columns.Add(addColumn);
customersGridView.Columns.Add(companyNameColumn);
customersGridView.Columns.Add(cityColumn);
// Programmatically register the event handling methods.
customersGridView.RowCommand += new GridViewCommandEventHandler(this.CustomersGridView_RowCommand);
customersGridView.RowCreated += new GridViewRowEventHandler(this.CustomersGridView_RowCreated);
// Add the GridView object to the Controls collection
// of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(customersGridView);
}
void CustomersGridView_RowCommand(Object sender, GridViewCommandEventArgs e)
{
// If multiple ButtonField columns are used, use the
// CommandName property to determine which button was clicked.
if(e.CommandName=="Add")
{
// Convert the row index stored in the CommandArgument
// property to an Integer.
int index = Convert.ToInt32(e.CommandArgument);
// Retrieve the row that contains the button clicked
// by the user from the Rows collection. Use the
// CommandSource property to access the GridView control.
GridView customersGridView = (GridView)e.CommandSource;
GridViewRow row = customersGridView.Rows[index];
// Create a new ListItem object for the customer in the row.
ListItem item = new ListItem();
item.Text = Server.HtmlDecode(row.Cells[1].Text) + " " + Server.HtmlDecode(row.Cells[2].Text);
// If the author is not already in the ListBox, add the ListItem
// object to the Items collection of a ListBox control.
if(!CustomersListBox.Items.Contains(item))
{
CustomersListBox.Items.Add(item);
}
}
}
void CustomersGridView_RowCreated(Object sender, GridViewRowEventArgs e)
{
// The GridViewCommandEventArgs class does not contain a
// property that indicates which row's command button was
// clicked. To identify which row was clicked, use the button's
// CommandArgument property by setting it to the row's index.
if(e.Row.RowType == DataControlRowType.DataRow)
{
// Retrieve the LinkButton control from the first column.
LinkButton addButton = (LinkButton)e.Row.Cells[0].Controls[0];
// Set the LinkButton's CommandArgument property with the
// row's index.
addButton.CommandArgument = e.Row.RowIndex.ToString();
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewCommandEventHandler Example</h3>
<table width="100%">
<tr>
<td style="width:50%">
<asp:placeholder id="GridViewPlaceHolder"
runat="Server"/>
</td>
<td style="vertical-align:top; width:50%">
Customers: <br/>
<asp:listbox id="CustomersListBox"
runat="server"/>
</td>
</tr>
</table>
<!-- 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="CustomersSource"
selectcommand="Select [CustomerID], [CompanyName], [City] 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 Page_Load(ByVal sender As Object, ByVal e As EventArgs)
' Create a new GridView object.
Dim customersGridView As New GridView()
' Set the GridView object's properties.
customersGridView.ID = "CustomersGridView"
customersGridView.DataSourceID = "CustomersSource"
customersGridView.AutoGenerateColumns = False
' Dynamically create the columns for the GridView control.
Dim addColumn As New ButtonField()
addColumn.CommandName = "Add"
addColumn.Text = "Add"
addColumn.ButtonType = ButtonType.Link
Dim companyNameColumn As New BoundField()
companyNameColumn.DataField = "CompanyName"
companyNameColumn.HeaderText = "Company Name"
Dim cityColumn As New BoundField()
cityColumn.DataField = "City"
cityColumn.HeaderText = "City"
' Add the columns to the Columns collection
' of the GridView control.
customersGridView.Columns.Add(addColumn)
customersGridView.Columns.Add(companyNameColumn)
customersGridView.Columns.Add(cityColumn)
' Programmatically register the event handling methods.
AddHandler customersGridView.RowCommand, AddressOf CustomersGridView_RowCommand
AddHandler customersGridView.RowCreated, AddressOf CustomersGridView_RowCreated
' Add the GridView object to the Controls collection
' of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(customersGridView)
End Sub
Sub CustomersGridView_RowCommand(ByVal sender As Object, ByVal e As GridViewCommandEventArgs)
' If multiple ButtonField columns are used, use the
' CommandName property to determine which button was clicked.
If e.CommandName = "Add" Then
' Convert the row index stored in the CommandArgument
' property to an Integer.
Dim index As Integer = Convert.ToInt32(e.CommandArgument)
' Retrieve the row that contains the button clicked
' by the user from the Rows collection. Use the
' CommandSource property to access the GridView control.
Dim customersGridView As GridView = CType(e.CommandSource, GridView)
Dim row As GridViewRow = customersGridView.Rows(index)
' Create a new ListItem object for the customer in the row.
Dim item As New ListItem()
item.Text = Server.HtmlDecode(row.Cells(1).Text) + " " + Server.HtmlDecode(row.Cells(2).Text)
' If the author is not already in the ListBox, add the ListItem
' object to the Items collection of a ListBox control.
If Not CustomersListBox.Items.Contains(item) Then
CustomersListBox.Items.Add(item)
End If
End If
End Sub
Sub CustomersGridView_RowCreated(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
' The GridViewCommandEventArgs class does not contain a
' property that indicates which row's command button was
' clicked. To identify which row was clicked, use the button's
' CommandArgument property by setting it to the row's index.
If e.Row.RowType = DataControlRowType.DataRow Then
' Retrieve the LinkButton control from the first column.
Dim addButton As LinkButton = CType(e.Row.Cells(0).Controls(0), LinkButton)
' Set the LinkButton's CommandArgument property with the
' row's index.
addButton.CommandArgument = e.Row.RowIndex.ToString()
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewCommandEventHandler Example</h3>
<table width="100%">
<tr>
<td style="width:50%">
<asp:placeholder id="GridViewPlaceHolder"
runat="Server"/>
</td>
<td style="vertical-align:top; width:50%">
Customers: <br/>
<asp:listbox id="CustomersListBox"
runat="server"/>
</td>
</tr>
</table>
<!-- 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="CustomersSource"
selectcommand="Select [CustomerID], [CompanyName], [City] From [Customers]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Nell'esempio seguente viene illustrato come aggiungere in modo dichiarativo un GridViewCommandEventHandler delegato all'evento RowCommand di un GridView controllo .
<%@ 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 ContactsGridView_RowCommand(Object sender, GridViewCommandEventArgs e)
{
// If multiple buttons are used in a GridView control, use the
// CommandName property to determine which button was clicked.
if(e.CommandName=="Add")
{
// Convert the row index stored in the CommandArgument
// property to an Integer.
int index = Convert.ToInt32(e.CommandArgument);
// Retrieve the row that contains the button clicked
// by the user from the Rows collection.
GridViewRow row = ContactsGridView.Rows[index];
// Create a new ListItem object for the contact in the row.
ListItem item = new ListItem();
item.Text = Server.HtmlDecode(row.Cells[2].Text) + " " +
Server.HtmlDecode(row.Cells[3].Text);
// If the contact is not already in the ListBox, add the ListItem
// object to the Items collection of the ListBox control.
if (!ContactsListBox.Items.Contains(item))
{
ContactsListBox.Items.Add(item);
}
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridView RowCommand Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridView RowCommand Example</h3>
<table width="100%">
<tr>
<td style="width:50%">
<asp:gridview id="ContactsGridView"
datasourceid="ContactsSource"
allowpaging="true"
autogeneratecolumns="false"
onrowcommand="ContactsGridView_RowCommand"
runat="server">
<columns>
<asp:buttonfield buttontype="Link"
commandname="Add"
text="Add"/>
<asp:boundfield datafield="ContactID"
headertext="Contact ID"/>
<asp:boundfield datafield="FirstName"
headertext="First Name"/>
<asp:boundfield datafield="LastName"
headertext="Last Name"/>
</columns>
</asp:gridview>
</td>
<td style="vertical-align:top; width:50%">
Contacts: <br/>
<asp:listbox id="ContactsListBox"
runat="server" Height="200px" Width="200px"/>
</td>
</tr>
</table>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the AdventureWorks sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:sqldatasource id="ContactsSource"
selectcommand="Select [ContactID], [FirstName], [LastName] From Person.Contact"
connectionstring="<%$ ConnectionStrings:AdventureWorks_DataConnectionString%>"
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 ContactsGridView_RowCommand(ByVal sender As Object, ByVal e As GridViewCommandEventArgs)
' If multiple buttons are used in a GridView control, use the
' CommandName property to determine which button was clicked.
If e.CommandName = "Add" Then
' Convert the row index stored in the CommandArgument
' property to an Integer.
Dim index As Integer = Convert.ToInt32(e.CommandArgument)
' Retrieve the row that contains the button clicked
' by the user from the Rows collection.
Dim row As GridViewRow = ContactsGridView.Rows(index)
' Create a new ListItem object for the contact in the row.
Dim item As New ListItem()
item.Text = Server.HtmlDecode(row.Cells(2).Text) & " " & _
Server.HtmlDecode(row.Cells(3).Text)
' If the contact is not already in the ListBox, add the ListItem
' object to the Items collection of the ListBox control.
If Not ContactsListBox.Items.Contains(item) Then
ContactsListBox.Items.Add(item)
End If
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>GridView RowCommand Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridView RowCommand Example</h3>
<table width="100%">
<tr>
<td style="width:50%">
<asp:gridview id="ContactsGridView"
datasourceid="ContactsSource"
allowpaging="true"
autogeneratecolumns="false"
onrowcommand="ContactsGridView_RowCommand"
runat="server">
<columns>
<asp:buttonfield buttontype="Link"
commandname="Add"
text="Add"/>
<asp:boundfield datafield="ContactID"
headertext="Contact ID"/>
<asp:boundfield datafield="FirstName"
headertext="First Name"/>
<asp:boundfield datafield="LastName"
headertext="Last Name"/>
</columns>
</asp:gridview>
</td>
<td style="vertical-align:top; width:50%">
Contacts: <br/>
<asp:listbox id="ContactsListBox"
runat="server" Height="200px" Width="200px"/>
</td>
</tr>
</table>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the AdventureWorks sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:sqldatasource id="ContactsSource"
selectcommand="Select [ContactID], [FirstName], [LastName] From Person.Contact"
connectionstring="<%$ ConnectionStrings:AdventureWorks_DataConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Commenti
L'evento RowCommand viene generato quando si fa clic su un pulsante all'interno del GridView controllo. In questo modo è possibile fornire un metodo di gestione degli eventi che esegue una routine personalizzata ogni volta che si verifica questo evento.
Nota
Il GridView controllo genera anche altri eventi specializzati quando si fa clic su determinati pulsanti (pulsanti con la CommandName proprietà impostata su "Elimina", "Aggiorna" e "Pagina", ad esempio). Quando si usa uno di questi pulsanti, è consigliabile gestire uno degli eventi specializzati forniti dal controllo ( ad esempio RowDeleted o RowDeleting).
Quando si crea un delegato GridViewCommandEventHandler, si identifica il metodo che gestirà l'evento. Per associare l'evento al gestore eventi in uso, aggiungere all'evento un'istanza del delegato. Il gestore eventi viene chiamato ogni volta che si verifica l'evento, a meno che non venga rimosso il delegato. Per altre informazioni sui delegati del gestore eventi, vedere Gestione e generazione di eventi.
Metodi di estensione
| GetMethodInfo(Delegate) |
Ottiene un oggetto che rappresenta il metodo rappresentato dal delegato specificato. |
Si applica a
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