GridViewSelectEventHandler Делегат
Определение
Важно!
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Представляет метод, обрабатывающий событие SelectedIndexChanging элемента управления GridView.
public delegate void GridViewSelectEventHandler(System::Object ^ sender, GridViewSelectEventArgs ^ e);public delegate void GridViewSelectEventHandler(object sender, GridViewSelectEventArgs e);type GridViewSelectEventHandler = delegate of obj * GridViewSelectEventArgs -> unitPublic Delegate Sub GridViewSelectEventHandler(sender As Object, e As GridViewSelectEventArgs)Параметры
- sender
- Object
Источник события.
Объект GridViewSelectEventArgs, содержащий данные события.
Примеры
В следующем примере показано, как программным способом GridViewSelectEventHandler добавить делегат в SelectedIndexChanging событие GridView элемента управления .
<%@ 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 authorGridView = new GridView();
// Set the GridView object's properties.
authorGridView.ID = "AuthorGridView";
authorGridView.DataSourceID = "AuthorsSqlDataSource";
authorGridView.AutoGenerateColumns = true;
authorGridView.AutoGenerateSelectButton = true;
authorGridView.AllowPaging = true;
authorGridView.SelectedIndex = 1;
authorGridView.SelectedRowStyle.BackColor = System.Drawing.Color.LightCyan;
authorGridView.SelectedRowStyle.ForeColor = System.Drawing.Color.DarkBlue;
authorGridView.SelectedRowStyle.Font.Bold = true;
// Programmatically register the event-handling methods.
authorGridView.SelectedIndexChanged += new EventHandler(this.AuthorsGridView_SelectedIndexChanged);
authorGridView.SelectedIndexChanging += new GridViewSelectEventHandler(this.AuthorsGridView_SelectedIndexChanging);
// Add the GridView object to the Controls collection
// of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(authorGridView);
}
void AuthorsGridView_SelectedIndexChanged(Object sender, EventArgs e)
{
// Get the currently selected row using the SelectedRow property.
GridView AuthorsGridView = (GridView)sender;
GridViewRow row = AuthorsGridView.SelectedRow;
// Display the author's name from the selected row.
// In this example, the second and third columns contain
// the author's last and first name, respectively.
Message.Text = "You selected " + row.Cells[2].Text +
" " + row.Cells[1].Text + ".";
}
void AuthorsGridView_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.
GridView AuthorsGridView = (GridView)sender;
GridViewRow row = AuthorsGridView.Rows[e.NewSelectedIndex];
// If the user selects an author with the last name White,
// cancel the selection operation and display an error message.
if(row.Cells[1].Text == "White")
{
e.Cancel = true;
Message.Text = "You cannot select " + row.Cells[2].Text +
" " + row.Cells[1].Text + ".";
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewSelectEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewSelectEventHandler Example</h3>
<asp:placeholder id="GridViewPlaceHolder"
runat="Server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Pubs sample database. -->
<asp:sqldatasource id="AuthorsSqlDataSource"
selectcommand="SELECT [au_lname], [au_fname], [address], [city], [state], [zip], [contract] FROM [authors]"
connectionstring="server=localhost;database=pubs;integrated security=SSPI"
runat="server">
</asp:sqldatasource>
<br/>
<asp:label id="Message"
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 authorGridView As GridView = New GridView
' Set the GridView object's properties.
authorGridView.ID = "AuthorGridView"
authorGridView.DataSourceID = "AuthorsSqlDataSource"
authorGridView.AutoGenerateColumns = True
authorGridView.AutoGenerateSelectButton = True
authorGridView.AllowPaging = True
authorGridView.SelectedIndex = 1
authorGridView.SelectedRowStyle.BackColor = System.Drawing.Color.LightCyan
authorGridView.SelectedRowStyle.ForeColor = System.Drawing.Color.DarkBlue
authorGridView.SelectedRowStyle.Font.Bold = True
' Programmatically register the event-handling methods.
AddHandler authorGridView.SelectedIndexChanged, AddressOf AuthorsGridView_SelectedIndexChanged
AddHandler authorGridView.SelectedIndexChanging, AddressOf AuthorsGridView_SelectedIndexChanging
' Add the GridView object to the Controls collection
' of the PlaceHolder control.
GridViewPlaceHolder.Controls.Add(authorGridView)
End Sub
Sub AuthorsGridView_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
' Get the currently selected row using the SelectedRow property.
Dim AuthorsGridView As GridView = CType(sender, GridView)
Dim row As GridViewRow = AuthorsGridView.SelectedRow
' Display the author's name from the selected row.
' In this example, the second and third columns contain
' the author's last and first name, respectively.
Message.Text = "You selected " & row.Cells(2).Text & _
" " & row.Cells(1).Text & "."
End Sub
Sub AuthorsGridView_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 AuthorsGridView As GridView = CType(sender, GridView)
Dim row As GridViewRow = AuthorsGridView.Rows(e.NewSelectedIndex)
' If the user selects an author with the last name White,
' cancel the selection operation and display an error message.
If row.Cells(1).Text = "White"
e.Cancel = true
Message.Text = "You cannot select " & row.Cells(2).Text & _
" " & row.Cells(1).Text & "."
End If
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>GridViewSelectEventHandler Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>GridViewSelectEventHandler Example</h3>
<asp:placeholder id="GridViewPlaceHolder"
runat="Server"/>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the Pubs sample database. -->
<asp:sqldatasource id="AuthorsSqlDataSource"
selectcommand="SELECT [au_lname], [au_fname], [address], [city], [state], [zip], [contract] FROM [authors]"
connectionstring="server=localhost;database=pubs;integrated security=SSPI"
runat="server">
</asp:sqldatasource>
<br/>
<asp:label id="Message"
runat="server"/>
</form>
</body>
</html>
В следующем примере показано, как декларативно добавить GridViewSelectEventHandler делегат в SelectedIndexChanging событие GridView элемента управления .
<%@ 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>
Комментарии
Событие SelectedIndexChanging возникает при нажатии кнопки Выбрать (кнопка со свойством CommandName "Выбрать"), но до того, как GridView элемент управления обработает операцию выбора. Это позволяет предоставить метод обработки событий, который выполняет пользовательскую подпрограмму, например отмену операции выбора, при каждом возникновении этого события.
При создании делегата GridViewSelectEventHandler 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
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