FormViewCommandEventHandler Делегат
Определение
Важно!
Некоторые сведения относятся к предварительной версии продукта, в которую до выпуска могут быть внесены существенные изменения. Майкрософт не предоставляет никаких гарантий, явных или подразумеваемых, относительно приведенных здесь сведений.
Представляет метод, обрабатывающий событие ItemCommand элемента управления FormView. Этот класс не наследуется.
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)Параметры
- sender
- Object
Источник события.
Объект FormViewCommandEventArgs, содержащий данные события.
Примеры
В следующем примере показано, как программным способом FormViewCommandEventHandler добавить делегат в ItemCommand событие FormView элемента управления .
<%@ 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>
В следующем примере показано, как декларативно добавить FormViewCommandEventHandler делегат в ItemCommand событие FormView элемента управления .
<%@ 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>
Комментарии
Событие ItemCommand возникает при нажатии кнопки в элементе FormView управления. Это позволяет предоставить метод обработки событий, который выполняет настраиваемую подпрограмму при каждом возникновении этого события.
Кнопки в элементе FormView управления также могут вызывать некоторые встроенные функции элемента управления. Чтобы выполнить одну из этих операций, задайте CommandName для свойства кнопки одно из значений в следующей таблице.
| Значение CommandName | Описание |
|---|---|
| "Отмена" | Отменяет операцию редактирования или вставки и возвращает FormView элемент управления в режим, заданный свойством DefaultMode . Вызывает ModeChanged события и ModeChanging . |
| "Удалить" | Удаляет текущую запись. Вызывает ItemDeleted события и ItemDeleting . |
| "Изменить" | Переводит элемент управления в FormView режим редактирования. Вызывает ModeChanged события и ModeChanging . |
| "Вставка" | Вставляет текущую запись в источник данных. Вызывает ItemInserted события и ItemInserting . |
| "Новый" | Переводит элемент управления в FormView режим вставки. Вызывает ModeChanged события и ModeChanging . |
| "Page" | Выполняет операцию разбиения по страницам. CommandArgument Задайте для свойства кнопки значения First, Last, Next, Prev или номер страницы, чтобы указать тип выполняемой операции разбиения по страницам. Вызывает PageIndexChanged события и PageIndexChanging . |
| "Обновить" | Обновляет текущую запись в источнике данных. Вызывает ItemUpdated события и ItemUpdating . |
ItemCommand Хотя событие возникает при нажатии кнопки, указанной в предыдущей таблице, рекомендуется обрабатывать события, перечисленные в таблице, для операции.
При создании делегата FormViewCommandEventHandler необходимо указать метод, обрабатывающий событие. Чтобы связать событие с обработчиком событий, нужно добавить в событие экземпляр делегата. Обработчик событий вызывается всякий раз, когда происходит событие, если делегат не удален. Дополнительные сведения о делегатах обработчика событий см. в разделе Обработка и вызов событий.
Методы расширения
| GetMethodInfo(Delegate) |
Получает объект, представляющий метод, представленный указанным делегатом. |
Применяется к
См. также раздел
Совместная работа с нами на GitHub
Источник этого содержимого можно найти на GitHub, где также можно создавать и просматривать проблемы и запросы на вытягивание. Дополнительные сведения см. в нашем руководстве для участников.
Обратная связь
Ожидается в ближайшее время: в течение 2024 года мы постепенно откажемся от GitHub Issues как механизма обратной связи для контента и заменим его новой системой обратной связи. Дополнительные сведения см. в разделе https://aka.ms/ContentUserFeedback.
Отправить и просмотреть отзыв по