FormViewCommandEventHandler Delegato
Definizione
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.
Rappresenta il metodo che gestisce l'evento ItemCommand di un controllo FormView. La classe non può essere ereditata.
public delegate void FormViewCommandEventHandler(System::Object ^ sender, FormViewCommandEventArgs ^ e);public delegate void FormViewCommandEventHandler(object sender, FormViewCommandEventArgs e);type FormViewCommandEventHandler = delegate of obj * FormViewCommandEventArgs -> unitPublic Delegate Sub FormViewCommandEventHandler(sender As Object, e As FormViewCommandEventArgs)Parametri
- sender
- Object
Origine dell'evento.
Oggetto FormViewCommandEventArgs che contiene i dati dell'evento.
Esempio
Nell'esempio seguente viene illustrato come aggiungere un FormViewCommandEventHandler delegato a livello di codice all'evento ItemCommand di un FormView controllo .
<%@ page language="C#" %>
<%@ import namespace="System.Data"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
// To dynamically create a template for a FormView control,
// you must create a custom template class to represent
// the template. This template class represents the item
// template for a FormView control.
private sealed class EmployeeTemplate : ITemplate
{
// When implementing the ITemplate interface, you must
// implement the InstantiateIn method. The FormView
// control calls this method to create the template's
// content.
void ITemplate.InstantiateIn(Control container)
{
// Create the child controls contained in the template.
// For this example, the item template displays the
// FirstName and LastName fields from the data source.
// To support data binding, create event handlers
// for the DataBinding event of each child control.
// The event handlers must bind the appropriate value
// to each control.
Label firstNameLabel = new Label();
firstNameLabel.ID = "FirstNameLabel";
firstNameLabel.DataBinding += new EventHandler(FirstNameLabel_DataBinding);
LiteralControl nameLineBreak = new LiteralControl("<br/>");
LiteralControl buttonLineBreak = new LiteralControl("<br/>");
Label lastNameLabel = new Label();
lastNameLabel.ID = "LastNameLabel";
lastNameLabel.DataBinding += new EventHandler(LastNameLabel_DataBinding);
// Create a custom button control to display in the item
// template. When a button within a FormView control is
// clicked, the ItemCommand event is raised. The ItemCommand
// event is used to handle the clicking of this button.
Button displayButton = new Button();
displayButton.ID = "AddButton";
displayButton.CommandName = "Display";
displayButton.Text = "Display Employee";
// Add the controls to the Controls collection of the
// container control.
container.Controls.Add(firstNameLabel);
container.Controls.Add(nameLineBreak);
container.Controls.Add(lastNameLabel);
container.Controls.Add(buttonLineBreak);
container.Controls.Add(displayButton);
}
// This event handler binds the value of the FirstName field
// to the FirstNameLabel Label control displayed in the template.
private void FirstNameLabel_DataBinding(Object sender, EventArgs e)
{
// Use the sender parameter to retrieve the Label control
// being bound to data.
Label firstNameLabelControl = (Label)sender;
// Retrieve the value to bind to the Label control. First,
// use the NamingContainer property to retrieve the parent
// control of the Label control. In this example, the parent
// control is the FormView control.
FormView formViewContainer = (FormView)firstNameLabelControl.NamingContainer;
// Get the data item bound to the FormView control.
DataRowView rowView = (DataRowView)formViewContainer.DataItem;
// Use the data item to retrieve the value of the FirstName field.
// Set the Text property of the Label control to this value.
firstNameLabelControl.Text = rowView["FirstName"].ToString();
}
// This event handler binds the value of the LastName field
// to the LastNameLabel Label control displayed in the template.
private void LastNameLabel_DataBinding(Object sender, EventArgs e)
{
// Use the sender parameter to retrieve the Label control
// being bound to data.
Label lastNameLabelControl = (Label)sender;
// Retrieve the value to bind to the Label control. First,
// use the NamingContainer property to retrieve the parent
// control of the Label control. In this example, the parent
// control is the FormView control.
FormView formViewContainer = (FormView)lastNameLabelControl.NamingContainer;
// Get the data item bound to the FormView control.
DataRowView rowView = (DataRowView)formViewContainer.DataItem;
// Use the data item to retrieve the value of the LastName field.
// Set the Text property of the Label control to this value.
lastNameLabelControl.Text = rowView["LastName"].ToString();
}
}
void Page_Load(Object sender, EventArgs e)
{
// Create a new FormView object.
FormView employeesFormView = new FormView();
// Set the FormView object's properties.
employeesFormView.ID = "EmployeesFormView";
employeesFormView.DataSourceID = "EmployeeSource";
employeesFormView.AllowPaging = true;
employeesFormView.HeaderText = "Employee Name";
// Programmatically register the event handlers for the
// FormView control.
employeesFormView.ItemCommand += new FormViewCommandEventHandler(EmployeesFormView_ItemCommand);
employeesFormView.PageIndexChanged += new EventHandler(EmployeesFormView_PageIndexChanged);
// Create the dynamic template using the custom template class.
employeesFormView.ItemTemplate = new EmployeeTemplate();
// Add the FormView object to the Controls collection
// of the PlaceHolder control.
FormViewPlaceHolder.Controls.Add(employeesFormView);
}
void EmployeesFormView_ItemCommand(Object sender, FormViewCommandEventArgs e)
{
// The ItemCommand event is raised when any button within
// the FormView control is clicked. Use the CommandName property
// to determine which button was clicked.
if (e.CommandName == "Display")
{
// Use the sender parameter to get the FormView control
// that contains the button clicked.
FormView employeesFormView = (FormView)sender;
// Use the Row property to retrieve the data row.
FormViewRow row = employeesFormView.Row;
// Retrieve the FirstNameLabel and LastNameLabel Label controls
// from the data row.
Label firstNameLabel = (Label)row.FindControl("FirstNameLabel");
Label lastNameLabel = (Label)row.FindControl("LastNameLabel");
if (firstNameLabel != null && lastNameLabel != null)
{
// Display the employee's name.
MessageLabel.Text = firstNameLabel.Text + " " +
lastNameLabel.Text;
}
}
}
void EmployeesFormView_PageIndexChanged(Object sender, EventArgs e)
{
// Clear the message label when the user navigates to
// a different record.
MessageLabel.Text = "";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewCommandEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated FormView control. -->
<asp:placeholder id="FormViewPlaceHolder"
runat="server"/>
<br/><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="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
<%@ page language="VB" %>
<%@ import namespace="System.Data"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
' To dynamically create a template for a FormView control,
' you must create a custom template class to represent
' the template. This template class represents the item
' template for a FormView control.
Private NotInheritable Class EmployeeTemplate
Implements ITemplate
' When implementing the ITemplate interface, you must
' implement the InstantiateIn method. The FormView
' control calls this method to create the template's
' content.
Sub InstantiateIn(ByVal container As Control) Implements ITemplate.InstantiateIn
' Create the child controls contained in the template.
' For this example, the item template displays the
' FirstName and LastName fields from the data source.
' To support data-binding, create event handlers
' for the DataBinding event of each child control.
' The event handlers must bind the appropriate value
' to each control.
Dim firstNameLabel As New Label()
firstNameLabel.ID = "FirstNameLabel"
AddHandler firstNameLabel.DataBinding, AddressOf FirstNameLabel_DataBinding
Dim nameLineBreak As New LiteralControl("<br/>")
Dim buttonLineBreak As New LiteralControl("<br/>")
Dim lastNameLabel As New Label()
lastNameLabel.ID = "LastNameLabel"
AddHandler lastNameLabel.DataBinding, AddressOf LastNameLabel_DataBinding
' Create a custom button control to display in the item
' template. When a button within a FormView control is
' clicked, the ItemCommand event is raised. The ItemCommand
' event is used to handle the clicking of this button.
Dim displayButton As New Button()
displayButton.ID = "AddButton"
displayButton.CommandName = "Display"
displayButton.Text = "Display Employee"
' Add the controls to the Controls collection of the
' container control.
container.Controls.Add(firstNameLabel)
container.Controls.Add(nameLineBreak)
container.Controls.Add(lastNameLabel)
container.Controls.Add(buttonLineBreak)
container.Controls.Add(displayButton)
End Sub
' This event handler binds the value of the FirstName field
' to the FirstNameLabel Label control displayed in the template.
Private Sub FirstNameLabel_DataBinding(ByVal sender As Object, ByVal e As EventArgs)
' Use the sender parameter to retrieve the Label control
' being bound to data.
Dim firstNameLabelControl As Label = CType(sender, Label)
' Retrieve the value to bind to the Label control. First,
' use the NamingContainer property to retrieve the parent
' control of the Label control. In this example, the parent
' control is the FormView control.
Dim formViewContainer As FormView = CType(firstNameLabelControl.NamingContainer, FormView)
' Get the data item bound to the FormView control.
Dim rowView As DataRowView = CType(formViewContainer.DataItem, DataRowView)
' Use the data item to retrieve the value of the FirstName field.
' Set the Text property of the Label control to this value.
firstNameLabelControl.Text = rowView("FirstName").ToString()
End Sub
' This event handler binds the value of the LastName field
' to the LastNameLabel Label control displayed in the template.
Private Sub LastNameLabel_DataBinding(ByVal sender As Object, ByVal e As EventArgs)
' Use the sender parameter to retrieve the Label control
' being bound to data.
Dim lastNameLabelControl As Label = CType(sender, Label)
' Retrieve the value to bind to the Label control. First,
' use the NamingContainer property to retrieve the parent
' control of the Label control. In this example, the parent
' control is the FormView control.
Dim formViewContainer As FormView = CType(lastNameLabelControl.NamingContainer, FormView)
' Get the data item bound to the FormView control.
Dim rowView As DataRowView = CType(formViewContainer.DataItem, DataRowView)
' Use the data item to retrieve the value of the LastName field.
' Set the Text property of the Label control to this value.
lastNameLabelControl.Text = rowView("LastName").ToString()
End Sub
End Class
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
' Create a new FormView object.
Dim employeesFormView As New FormView()
' Set the FormView object's properties.
employeesFormView.ID = "EmployeesFormView"
employeesFormView.DataSourceID = "EmployeeSource"
employeesFormView.AllowPaging = True
employeesFormView.HeaderText = "Employee Name"
' Programmatically register the event handlers for the
' FormView control.
AddHandler employeesFormView.ItemCommand, AddressOf EmployeesFormView_ItemCommand
AddHandler employeesFormView.PageIndexChanged, AddressOf EmployeesFormView_PageIndexChanged
' Create the dynamic template using the custom template class.
employeesFormView.ItemTemplate = New EmployeeTemplate()
' Add the FormView object to the Controls collection
' of the PlaceHolder control.
FormViewPlaceHolder.Controls.Add(employeesFormView)
End Sub
Sub EmployeesFormView_ItemCommand(ByVal sender As Object, ByVal e As FormViewCommandEventArgs)
' The ItemCommand event is raised when any button within
' the FormView control is clicked. Use the CommandName property
' to determine which button was clicked.
If e.CommandName = "Display" Then
' Use the sender parameter to get the FormView control
' that contains the button clicked.
Dim employeesFormView As FormView = CType(sender, FormView)
' Use the Row property to retrieve the data row.
Dim row As FormViewRow = employeesFormView.Row
' Retrieve the FirstNameLabel and LastNameLabel Label controls
' from the data row.
Dim firstNameLabel As Label = CType(row.FindControl("FirstNameLabel"), Label)
Dim lastNameLabel As Label = CType(row.FindControl("LastNameLabel"), Label)
If firstNameLabel IsNot Nothing And lastNameLabel IsNot Nothing Then
' Display the employee's name.
MessageLabel.Text = firstNameLabel.Text & " " & _
lastNameLabel.Text()
End If
End If
End Sub
Sub EmployeesFormView_PageIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
' Clear the message label when the user navigates to
' a different record.
MessageLabel.Text = ""
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewCommandEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated FormView control. -->
<asp:placeholder id="FormViewPlaceHolder"
runat="server"/>
<br/><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="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Nell'esempio seguente viene illustrato come aggiungere in modo dichiarativo un FormViewCommandEventHandler delegato all'evento ItemCommand di un FormView controllo .
<%@ page language="C#" %>
<%@ import namespace="System.Data"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void EmployeesFormView_ItemCommand(Object sender, FormViewCommandEventArgs e)
{
// The ItemCommand event is raised when any button within
// the FormView control is clicked. Use the CommandName property
// to determine which button was clicked.
if (e.CommandName == "Display")
{
// Use the Row property to retrieve the data row.
FormViewRow row = EmployeesFormView.Row;
// Retrieve the FirstNameLabel and LastNameLabel Label controls
// from data row.
Label firstNameLabel = (Label)row.FindControl("FirstNameLabel");
Label lastNameLabel = (Label)row.FindControl("LastNameLabel");
if (firstNameLabel != null && lastNameLabel != null)
{
// Display the employee's name.
MessageLabel.Text = firstNameLabel.Text + " " +
lastNameLabel.Text;
}
}
}
void EmployeesFormView_PageIndexChanged(Object sender, EventArgs e)
{
// Clear the message label when the user navigates to
// a different record.
MessageLabel.Text = "";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewCommandEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated FormView control. -->
<asp:formview id="EmployeesFormView"
datasourceid="EmployeeSource"
allowpaging="True"
headertext="Employee Name"
onitemcommand="EmployeesFormView_ItemCommand"
onpageindexchanged="EmployeesFormView_PageIndexChanged"
runat="server">
<itemtemplate>
<asp:label id="FirstNameLabel"
text='<%# Eval("FirstName") %>'
runat="server"/>
<br/>
<asp:label id="LastNameLabel"
text='<%# Eval("LastName") %>'
runat="server"/>
<br/>
<asp:button
id="DisplayButton"
text="Display Employee"
commandname="Display"
runat="server"/>
</itemtemplate>
</asp:formview>
<br/><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="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
<%@ page language="VB" %>
<%@ import namespace="System.Data"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub EmployeesFormView_ItemCommand(ByVal sender As Object, ByVal e As FormViewCommandEventArgs) Handles EmployeesFormView.ItemCommand
' The ItemCommand event is raised when any button within
' the FormView control is clicked. Use the CommandName property
' to determine which button was clicked.
If e.CommandName = "Display" Then
' Use the Row property to retrieve the data row.
Dim row As FormViewRow = EmployeesFormView.Row
' Retrieve the FirstNameLabel and LastNameLabel Label controls
' from data row.
Dim firstNameLabel As Label = CType(row.FindControl("FirstNameLabel"), Label)
Dim lastNameLabel As Label = CType(row.FindControl("LastNameLabel"), Label)
If firstNameLabel IsNot Nothing And lastNameLabel IsNot Nothing Then
' Display the employee's name.
MessageLabel.Text = firstNameLabel.Text & " " & _
lastNameLabel.Text()
End If
End If
End Sub
Sub EmployeesFormView_PageIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles EmployeesFormView.PageIndexChanged
' Clear the message label when the user navigates to
' a different record.
MessageLabel.Text = ""
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>FormViewCommandEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>FormViewCommandEventHandler Example</h3>
<!-- Use a PlaceHolder control as the container for the -->
<!-- dynamically generated FormView control. -->
<asp:formview id="EmployeesFormView"
datasourceid="EmployeeSource"
allowpaging="True"
headertext="Employee Name"
runat="server">
<itemtemplate>
<asp:label id="FirstNameLabel"
text='<%# Eval("FirstName") %>'
runat="server"/>
<br/>
<asp:label id="LastNameLabel"
text='<%# Eval("LastName") %>'
runat="server"/>
<br/>
<asp:button
id="DisplayButton"
text="Display Employee"
commandname="Display"
runat="server"/>
</itemtemplate>
</asp:formview>
<br/><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="EmployeeSource"
selectcommand="Select [EmployeeID], [LastName], [FirstName] From [Employees]"
connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
runat="server"/>
</form>
</body>
</html>
Commenti
L'evento ItemCommand viene generato quando si fa clic su un pulsante all'interno del FormView 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.
I pulsanti all'interno di un FormView controllo possono anche richiamare alcune delle funzionalità predefinite del controllo. Per eseguire una di queste operazioni, impostare la CommandName proprietà di un pulsante su uno dei valori della tabella seguente.
| Valore CommandName | Descrizione |
|---|---|
| "Annulla" | Annulla un'operazione di modifica o inserimento e restituisce il FormView controllo alla modalità specificata dalla DefaultMode proprietà . Genera gli ModeChanged eventi e ModeChanging . |
| "Delete" | Elimina il record corrente. Genera gli ItemDeleted eventi e ItemDeleting . |
| "Modifica" | Inserisce il FormView controllo in modalità di modifica. Genera gli ModeChanged eventi e ModeChanging . |
| "Inserisci" | Inserisce il record corrente nell'origine dati. Genera gli ItemInserted eventi e ItemInserting . |
| "Nuovo" | Inserisce il FormView controllo in modalità di inserimento. Genera gli ModeChanged eventi e ModeChanging . |
| "Pagina" | Esegue un'operazione di paging. Impostare la CommandArgument proprietà del pulsante su "First", "Last", "Next", "Prev" o un numero di pagina per specificare il tipo di operazione di paging da eseguire. Genera gli PageIndexChanged eventi e PageIndexChanging . |
| "Aggiorna" | Aggiorna il record corrente nell'origine dati. Genera gli ItemUpdated eventi e ItemUpdating . |
Sebbene l'evento ItemCommand venga generato quando si fa clic su un pulsante elencato nella tabella precedente, è consigliabile gestire gli eventi elencati nella tabella per l'operazione.
Quando si crea un delegato FormViewCommandEventHandler, 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. |
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