FormViewCommandEventHandler Delegado
Definición
Importante
Parte de la información hace referencia a la versión preliminar del producto, que puede haberse modificado sustancialmente antes de lanzar la versión definitiva. Microsoft no otorga ninguna garantía, explícita o implícita, con respecto a la información proporcionada aquí.
Representa el método que controla el evento ItemCommand de un control FormView. Esta clase no puede heredarse.
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)Parámetros
- sender
- Object
Origen del evento.
Objeto FormViewCommandEventArgs que contiene los datos del evento.
Ejemplos
En el ejemplo siguiente se muestra cómo agregar mediante programación un FormViewCommandEventHandler delegado al ItemCommand evento de un FormView control .
<%@ 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>
En el ejemplo siguiente se muestra cómo agregar mediante declaración un FormViewCommandEventHandler delegado al ItemCommand evento de un FormView control .
<%@ 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>
Comentarios
El ItemCommand evento se genera cuando se hace clic en un botón dentro del FormView control. Esto le permite proporcionar un método de control de eventos que realiza una rutina personalizada cada vez que se produce este evento.
Los botones de un FormView control también pueden invocar parte de la funcionalidad integrada del control. Para realizar una de estas operaciones, establezca la CommandName propiedad de un botón en uno de los valores de la tabla siguiente.
| Valor commandName | Descripción |
|---|---|
| "Cancelar" | Cancela una operación de edición o inserción y devuelve el FormView control al modo especificado por la DefaultMode propiedad . Genera los ModeChanged eventos y ModeChanging . |
| “Eliminar” | Elimina el registro actual. Genera los ItemDeleted eventos y ItemDeleting . |
| "Editar" | Coloca el FormView control en modo de edición. Genera los ModeChanged eventos y ModeChanging . |
| "Insertar" | Inserta el registro actual en el origen de datos. Genera los ItemInserted eventos y ItemInserting . |
| "Nuevo" | Coloca el FormView control en modo de inserción. Genera los ModeChanged eventos y ModeChanging . |
| "Página" | Realiza una operación de paginación. Establezca la CommandArgument propiedad del botón en "First", "Last", "Next", "Prev" o un número de página para especificar el tipo de operación de paginación que se va a realizar. Genera los PageIndexChanged eventos y PageIndexChanging . |
| "Actualizar" | Actualiza el registro actual en el origen de datos. Genera los ItemUpdated eventos y ItemUpdating . |
Aunque se genera el ItemCommand evento cuando se hace clic en un botón que aparece en la tabla anterior, se recomienda controlar los eventos enumerados en la tabla para la operación.
Cuando se crea un delegado FormViewCommandEventHandler, se identifica el método que controlará el evento. Para asociar el evento al controlador, se debe agregar una instancia del delegado al evento. Siempre que se produce el evento, se llama a su controlador, a menos que se quite el delegado. Para obtener más información sobre los delegados del controlador de eventos, vea Control y generación de eventos.
Métodos de extensión
| GetMethodInfo(Delegate) |
Obtiene un objeto que representa el método representado por el delegado especificado. |
Se aplica a
Consulte también
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