Utilizzo del controllo UpdatePanel ASP.NET con più controlli con associazione a dati
Aggiornamento: novembre 2007
Per migliorare l'esperienza utente nelle applicazioni ASP.NET compatibili con AJAX è possibile utilizzare il rendering a pagina parziale. Grazie a questa funzionalità, quando si verifica un postback non è necessario aggiornare l'intera pagina bensì soltanto una parte specificata. Di conseguenza, gli utenti non devono attendere l'aggiornamento dell'intera pagina a ogni postback.
In questo argomento si presuppone che l'utente abbia acquisito familiarità con il controllo UpdatePanel. In caso contrario, consultare gli argomenti seguenti:
Per attivare il rendering a pagina parziale è possibile utilizzare i controlli server Web UpdatePanel e ScriptManager. Il controllo UpdatePanel identifica un'area aggiornabile di una pagina. Il controllo ScriptManager tiene traccia dei controlli UpdatePanel presenti in una pagina e dei controlli che comportano l'aggiornamento dei controlli UpdatePanel. I controlli contenuti in un controllo UpdatePanel che generano un postback vengono identificati automaticamente come trigger del pannello di aggiornamento. È inoltre possibile specificare controlli esterni a un controllo UpdatePanel. I trigger esterni possono essere controlli figlio di un altro controllo UpdatePanel. Per ulteriori informazioni, vedere Cenni preliminari sul rendering a pagina parziale e Cenni preliminari sui controlli UpdatePanel.
Questo argomento contiene le sezioni seguenti:
Utilizzo di più controlli UpdatePanel in una pagina
Disattivazione dei trigger automatici
Gestione dei trigger e aggiornamento di un controllo UpdatePanel a livello di codice
Attivazione del rendering a pagina parziale in un controllo personalizzato
Utilizzo di più controlli UpdatePanel in una pagina
In una determinata pagina è possibile inserire un numero illimitato di controlli UpdatePanel. Ciò consente di specificare all'interno di una pagina più aree che vengono aggiornate indipendentemente dall'intera pagina e dalle altre aree.
Per impostazione predefinita, la proprietà UpdateMode di un controllo UpdatePanel è impostata su Always. Ciò significa che a ogni attivazione di un aggiornamento a pagina parziale il controllo UpdatePanel aggiorna la pagina, anche se il trigger non riguardava tale controllo UpdatePanel. Per garantire che il controllo UpdatePanel venga aggiornato solo quando richiesto in modo esplicito è possibile impostare la proprietà UpdateMode del controllo UpdatePanel su Conditional.
L'esempio seguente illustra due controlli UpdatePanel. Uno di essi contiene controlli Web che accettano l'input dell'utente, mentre l'altro visualizza quanto immesso dall'utente. In entrambi i controlli UpdatePanel la proprietà UpdateMode è impostata su Conditional. Di conseguenza, se un utente fa clic sul pulsante Annulla per cancellare i campi del form di input, viene aggiornato soltanto il form di input del controllo UpdatePanel. Se un utente fa clic sul pulsante Inserisci per inviare il form, vengono aggiornati entrambi i controlli UpdatePanel.
<%@ Page Language="VB" %>
<%@ Import Namespace="System.Collections.Generic" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" >
<title>Enter New Employees</title>
<script >
Private EmployeeList As List(Of Employee)
Protected Sub Page_Load()
If Not IsPostBack Then
EmployeeList = New List(Of Employee)
EmployeeList.Add(New Employee(1, "Jump", "Dan"))
EmployeeList.Add(New Employee(2, "Kirwan", "Yvette"))
ViewState("EmployeeList") = EmployeeList
Else
EmployeeList = CType(ViewState("EmployeeList"), List(Of Employee))
End If
EmployeesGridView.DataSource = EmployeeList
EmployeesGridView.DataBind()
End Sub
Protected Sub InsertButton_Click(ByVal sender As Object, ByVal e As EventArgs)
If String.IsNullOrEmpty(FirstNameTextBox.Text) Or _
String.IsNullOrEmpty(LastNameTextBox.Text) Then Return
Dim employeeID As Integer = EmployeeList(EmployeeList.Count - 1).EmployeeID + 1
Dim lastName As String = Server.HtmlEncode(FirstNameTextBox.Text)
Dim firstName As String = Server.HtmlEncode(LastNameTextBox.Text)
FirstNameTextBox.Text = String.Empty
LastNameTextBox.Text = String.Empty
EmployeeList.Add(New Employee(employeeID, lastName, firstName))
ViewState("EmployeeList") = EmployeeList
EmployeesGridView.DataBind()
EmployeesGridView.PageIndex = EmployeesGridView.PageCount
End Sub
Protected Sub CancelButton_Click(ByVal sender As Object, ByVal e As EventArgs)
FirstNameTextBox.Text = String.Empty
LastNameTextBox.Text = String.Empty
End Sub
<Serializable()> _
Public Class Employee
Private _employeeID As Integer
Private _lastName As String
Private _firstName As String
Public ReadOnly Property EmployeeID() As Integer
Get
Return _employeeID
End Get
End Property
Public ReadOnly Property LastName() As String
Get
Return _lastName
End Get
End Property
Public ReadOnly Property FirstName() As String
Get
Return _firstName
End Get
End Property
Public Sub New(ByVal employeeID As Integer, ByVal lastName As String, ByVal firstName As String)
_employeeID = employeeID
_lastName = lastName
_firstName = firstName
End Sub
End Class
</script>
</head>
<body>
<form id="form1" >
<div>
</div>
<asp:ScriptManager ID="ScriptManager1" EnablePartialRendering="true" />
<table>
<tr>
<td style="height: 206px" valign="top">
<asp:UpdatePanel ID="InsertEmployeeUpdatePanel" UpdateMode="Conditional">
<ContentTemplate>
<table cellpadding="2" border="0" style="background-color:#7C6F57">
<tr>
<td><asp:Label ID="FirstNameLabel" AssociatedControlID="FirstNameTextBox"
Text="First Name" ForeColor="White" /></td>
<td><asp:TextBox ID="FirstNameTextBox" /></td>
</tr>
<tr>
<td><asp:Label ID="LastNameLabel" AssociatedControlID="LastNameTextBox"
Text="Last Name" ForeColor="White" /></td>
<td><asp:TextBox ID="LastNameTextBox" /></td>
</tr>
<tr>
<td></td>
<td>
<asp:LinkButton ID="InsertButton" Text="Insert" OnClick="InsertButton_Click" ForeColor="White" />
<asp:LinkButton ID="Cancelbutton" Text="Cancel" OnClick="CancelButton_Click" ForeColor="White" />
</td>
</tr>
</table>
<asp:Label ID="InputTimeLabel"><%=DateTime.Now %></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
</td>
<td style="height: 206px" valign="top">
<asp:UpdatePanel ID="EmployeesUpdatePanel" UpdateMode="Conditional">
<ContentTemplate>
<asp:GridView ID="EmployeesGridView" BackColor="LightGoldenrodYellow" BorderColor="Tan"
BorderWidth="1px" CellPadding="2" ForeColor="Black" GridLines="None" AutoGenerateColumns="False">
<FooterStyle BackColor="Tan" />
<SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" />
<PagerStyle BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue" HorizontalAlign="Center" />
<HeaderStyle BackColor="Tan" Font-Bold="True" />
<AlternatingRowStyle BackColor="PaleGoldenrod" />
<Columns>
<asp:BoundField DataField="EmployeeID" HeaderText="Employee ID" />
<asp:BoundField DataField="LastName" HeaderText="Last Name" />
<asp:BoundField DataField="FirstName" HeaderText="First Name" />
</Columns>
<PagerSettings PageButtonCount="5" />
</asp:GridView>
<asp:Label ID="ListTimeLabel"><%=DateTime.Now %></asp:Label>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="InsertButton" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
</td>
</tr>
</table>
</form>
</body>
</html>
<%@ Page Language="C#" %>
<%@ Import Namespace="System.Collections.Generic" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head >
<title>Enter New Employees</title>
<script >
private List<Employee> EmployeeList;
protected void Page_Load()
{
if (!IsPostBack)
{
EmployeeList = new List<Employee>();
EmployeeList.Add(new Employee(1, "Jump", "Dan"));
EmployeeList.Add(new Employee(2, "Kirwan", "Yvette"));
ViewState["EmployeeList"] = EmployeeList;
}
else
EmployeeList = (List<Employee>)ViewState["EmployeeList"];
EmployeesGridView.DataSource = EmployeeList;
EmployeesGridView.DataBind();
}
protected void InsertButton_Click(object sender, EventArgs e)
{
if (String.IsNullOrEmpty(FirstNameTextBox.Text) ||
String.IsNullOrEmpty(LastNameTextBox.Text)) { return; }
int employeeID = EmployeeList[EmployeeList.Count-1].EmployeeID + 1;
string lastName = Server.HtmlEncode(FirstNameTextBox.Text);
string firstName = Server.HtmlEncode(LastNameTextBox.Text);
FirstNameTextBox.Text = String.Empty;
LastNameTextBox.Text = String.Empty;
EmployeeList.Add(new Employee(employeeID, lastName, firstName));
ViewState["EmployeeList"] = EmployeeList;
EmployeesGridView.DataBind();
EmployeesGridView.PageIndex = EmployeesGridView.PageCount;
}
protected void CancelButton_Click(object sender, EventArgs e)
{
FirstNameTextBox.Text = String.Empty;
LastNameTextBox.Text = String.Empty;
}
[Serializable]
public class Employee
{
private int _employeeID;
private string _lastName;
private string _firstName;
public int EmployeeID
{
get { return _employeeID; }
}
public string LastName
{
get { return _lastName; }
}
public string FirstName
{
get { return _firstName; }
}
public Employee(int employeeID, string lastName, string firstName)
{
_employeeID = employeeID;
_lastName = lastName;
_firstName = firstName;
}
}
</script>
</head>
<body>
<form id="form1" >
<div>
</div>
<asp:ScriptManager ID="ScriptManager1" EnablePartialRendering="true" />
<table>
<tr>
<td style="height: 206px" valign="top">
<asp:UpdatePanel ID="InsertEmployeeUpdatePanel" UpdateMode="Conditional">
<ContentTemplate>
<table cellpadding="2" border="0" style="background-color:#7C6F57">
<tr>
<td><asp:Label ID="FirstNameLabel" AssociatedControlID="FirstNameTextBox"
Text="First Name" ForeColor="White" /></td>
<td><asp:TextBox ID="FirstNameTextBox" /></td>
</tr>
<tr>
<td><asp:Label ID="LastNameLabel" AssociatedControlID="LastNameTextBox"
Text="Last Name" ForeColor="White" /></td>
<td><asp:TextBox ID="LastNameTextBox" /></td>
</tr>
<tr>
<td></td>
<td>
<asp:LinkButton ID="InsertButton" Text="Insert" OnClick="InsertButton_Click" ForeColor="White" />
<asp:LinkButton ID="Cancelbutton" Text="Cancel" OnClick="CancelButton_Click" ForeColor="White" />
</td>
</tr>
</table>
<asp:Label ID="InputTimeLabel"><%=DateTime.Now %></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
</td>
<td style="height: 206px" valign="top">
<asp:UpdatePanel ID="EmployeesUpdatePanel" UpdateMode="Conditional">
<ContentTemplate>
<asp:GridView ID="EmployeesGridView" BackColor="LightGoldenrodYellow" BorderColor="Tan"
BorderWidth="1px" CellPadding="2" ForeColor="Black" GridLines="None" AutoGenerateColumns="False">
<FooterStyle BackColor="Tan" />
<SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" />
<PagerStyle BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue" HorizontalAlign="Center" />
<HeaderStyle BackColor="Tan" Font-Bold="True" />
<AlternatingRowStyle BackColor="PaleGoldenrod" />
<Columns>
<asp:BoundField DataField="EmployeeID" HeaderText="Employee ID" />
<asp:BoundField DataField="LastName" HeaderText="Last Name" />
<asp:BoundField DataField="FirstName" HeaderText="First Name" />
</Columns>
<PagerSettings PageButtonCount="5" />
</asp:GridView>
<asp:Label ID="ListTimeLabel"><%=DateTime.Now %></asp:Label>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="InsertButton" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
</td>
</tr>
</table>
</form>
</body>
</html>
È inoltre possibile nidificare un controllo UpdatePanel in un altro controllo UpdatePanel. Se la proprietà UpdateMode è impostata su Conditional sia per il controllo esterno sia per il controllo nidificato, l'attivazione dell'aggiornamento del pannello interno non comporta l'aggiornamento del pannello esterno. Se tuttavia un trigger comporta l'aggiornamento del pannello esterno, anche il pannello interno viene aggiornato.
L'esempio seguente illustra un controllo GridView nidificato in un controllo UpdatePanel. Ogni riga del controllo GridView contiene un controllo GridView nidificato, ovvero un controllo UpdatePanel figlio. Quando un controllo GridView interno richiede una nuova pagina di record, le aree della pagina del pannello esterno e i pannelli contenuti nelle altre righe del controllo GridView esterno non vengono aggiornate. Quando il controllo GridView esterno visualizza una nuova pagina di record, sia le aree della pagina del pannello esterno sia quelle dei pannelli nidificati vengono aggiornate.
<%@ Page Language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head >
<title>Browse Departments</title>
<script >
Protected Sub DepartmentsGridView_RowDataBound(sender As object, e As GridViewRowEventArgs)
If e.Row.RowType = DataControlRowType.DataRow Then
Dim s As SqlDataSource = CType(e.Row.FindControl("EmployeesDataSource"), SqlDataSource)
Dim r As System.Data.DataRowView = CType(e.Row.DataItem, System.Data.DataRowView)
s.SelectParameters("DepartmentID").DefaultValue = r("DepartmentID").ToString()
End If
End Sub
</script>
</head>
<body>
<form id="form1" >
<div>
<asp:ScriptManager ID="ScriptManager1" EnablePartialRendering="true" />
<asp:UpdatePanel ID="UpdatePanel2" UpdateMode="Conditional">
<ContentTemplate>
<asp:GridView ID="DepartmentsGridView" AllowPaging="True" AllowSorting="True"
AutoGenerateColumns="False" CellPadding="4" DataSourceID="DepartmentDataSource"
ForeColor="#333333" GridLines="None" PageSize="3" OnRowDataBound="DepartmentsGridView_RowDataBound">
<FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
<Columns>
<asp:BoundField DataField="GroupName" HeaderText="Division" SortExpression="GroupName" >
<ItemStyle Width="200px" />
</asp:BoundField>
<asp:BoundField DataField="Name" HeaderText="Department Name" SortExpression="Name" >
<ItemStyle Width="160px" />
</asp:BoundField>
<asp:TemplateField HeaderText="Employees">
<ItemTemplate>
<asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional">
<ContentTemplate>
<asp:GridView ID="EmployeesGridView" AllowPaging="True" AllowSorting="True"
AutoGenerateColumns="False" BackColor="White" BorderColor="#999999" BorderStyle="None"
BorderWidth="1px" CellPadding="3" DataSourceID="EmployeesDataSource" GridLines="Vertical"
PageSize="4">
<FooterStyle BackColor="#CCCCCC" ForeColor="Black" />
<Columns>
<asp:BoundField DataField="FirstName" HeaderText="First Name" SortExpression="FirstName" >
<ItemStyle Width="80px" />
</asp:BoundField>
<asp:BoundField DataField="LastName" HeaderText="Last Name" SortExpression="LastName" >
<ItemStyle Width="160px" />
</asp:BoundField>
</Columns>
<RowStyle BackColor="#EEEEEE" ForeColor="Black" />
<SelectedRowStyle BackColor="#008A8C" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#999999" ForeColor="Black" HorizontalAlign="Center" />
<HeaderStyle BackColor="#000084" Font-Bold="True" ForeColor="White" />
<AlternatingRowStyle BackColor="Gainsboro" />
</asp:GridView>
<asp:Label ID="InnerTimeLabel"><%=DateTime.Now %></asp:Label>
<asp:SqlDataSource ID="EmployeesDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT HumanResources.EmployeeDepartmentHistory.DepartmentID,
HumanResources.vEmployee.EmployeeID,
HumanResources.vEmployee.FirstName,
HumanResources.vEmployee.LastName
FROM HumanResources.EmployeeDepartmentHistory
INNER JOIN HumanResources.vEmployee
ON HumanResources.EmployeeDepartmentHistory.EmployeeID = HumanResources.vEmployee.EmployeeID
WHERE HumanResources.EmployeeDepartmentHistory.DepartmentID = @DepartmentID
ORDER BY HumanResources.vEmployee.LastName ASC, HumanResources.vEmployee.FirstName ASC">
<SelectParameters>
<asp:Parameter Name="DepartmentID" DefaultValue="0" Type="int32" />
</SelectParameters>
</asp:SqlDataSource>
</ContentTemplate>
</asp:UpdatePanel>
</ItemTemplate>
<ItemStyle Height="170px" Width="260px" />
</asp:TemplateField>
</Columns>
<RowStyle BackColor="#F7F6F3" ForeColor="#333333" VerticalAlign="Top" />
<EditRowStyle BackColor="#999999" />
<SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
<PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
<HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" HorizontalAlign="Left" />
<AlternatingRowStyle BackColor="White" ForeColor="#284775" VerticalAlign="Top" />
</asp:GridView>
<asp:Label ID="OuterTimeLabel"><%=DateTime.Now %></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
<asp:SqlDataSource ID="DepartmentDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT DepartmentID, Name, GroupName FROM HumanResources.Department ORDER BY Name">
</asp:SqlDataSource>
</div>
</form>
</body>
</html>
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head >
<title>Browse Departments</title>
<script >
protected void DepartmentsGridView_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
SqlDataSource s = (SqlDataSource)e.Row.FindControl("EmployeesDataSource");
System.Data.DataRowView r = (System.Data.DataRowView)e.Row.DataItem;
s.SelectParameters["DepartmentID"].DefaultValue = r["DepartmentID"].ToString();
}
}
</script>
</head>
<body>
<form id="form1" >
<div>
<asp:ScriptManager ID="ScriptManager1" EnablePartialRendering="true" />
<asp:UpdatePanel ID="UpdatePanel2" UpdateMode="Conditional">
<ContentTemplate>
<asp:GridView ID="DepartmentsGridView" AllowPaging="True" AllowSorting="True"
AutoGenerateColumns="False" CellPadding="4" DataSourceID="DepartmentDataSource"
ForeColor="#333333" GridLines="None" PageSize="3" OnRowDataBound="DepartmentsGridView_RowDataBound">
<FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
<Columns>
<asp:BoundField DataField="GroupName" HeaderText="Division" SortExpression="GroupName" >
<ItemStyle Width="200px" />
</asp:BoundField>
<asp:BoundField DataField="Name" HeaderText="Department Name" SortExpression="Name" >
<ItemStyle Width="160px" />
</asp:BoundField>
<asp:TemplateField HeaderText="Employees">
<ItemTemplate>
<asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional">
<ContentTemplate>
<asp:GridView ID="EmployeesGridView" AllowPaging="True" AllowSorting="True"
AutoGenerateColumns="False" BackColor="White" BorderColor="#999999" BorderStyle="None"
BorderWidth="1px" CellPadding="3" DataSourceID="EmployeesDataSource" GridLines="Vertical"
PageSize="4">
<FooterStyle BackColor="#CCCCCC" ForeColor="Black" />
<Columns>
<asp:BoundField DataField="FirstName" HeaderText="First Name" SortExpression="FirstName" >
<ItemStyle Width="80px" />
</asp:BoundField>
<asp:BoundField DataField="LastName" HeaderText="Last Name" SortExpression="LastName" >
<ItemStyle Width="160px" />
</asp:BoundField>
</Columns>
<RowStyle BackColor="#EEEEEE" ForeColor="Black" />
<SelectedRowStyle BackColor="#008A8C" Font-Bold="True" ForeColor="White" />
<PagerStyle BackColor="#999999" ForeColor="Black" HorizontalAlign="Center" />
<HeaderStyle BackColor="#000084" Font-Bold="True" ForeColor="White" />
<AlternatingRowStyle BackColor="Gainsboro" />
</asp:GridView>
<asp:Label ID="InnerTimeLabel"><%=DateTime.Now %></asp:Label>
<asp:SqlDataSource ID="EmployeesDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT HumanResources.EmployeeDepartmentHistory.DepartmentID,
HumanResources.vEmployee.EmployeeID,
HumanResources.vEmployee.FirstName,
HumanResources.vEmployee.LastName
FROM HumanResources.EmployeeDepartmentHistory
INNER JOIN HumanResources.vEmployee
ON HumanResources.EmployeeDepartmentHistory.EmployeeID = HumanResources.vEmployee.EmployeeID
WHERE HumanResources.EmployeeDepartmentHistory.DepartmentID = @DepartmentID
ORDER BY HumanResources.vEmployee.LastName ASC, HumanResources.vEmployee.FirstName ASC">
<SelectParameters>
<asp:Parameter Name="DepartmentID" DefaultValue="0" Type="int32" />
</SelectParameters>
</asp:SqlDataSource>
</ContentTemplate>
</asp:UpdatePanel>
</ItemTemplate>
<ItemStyle Height="170px" Width="260px" />
</asp:TemplateField>
</Columns>
<RowStyle BackColor="#F7F6F3" ForeColor="#333333" VerticalAlign="Top" />
<EditRowStyle BackColor="#999999" />
<SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
<PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
<HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" HorizontalAlign="Left" />
<AlternatingRowStyle BackColor="White" ForeColor="#284775" VerticalAlign="Top" />
</asp:GridView>
<asp:Label ID="OuterTimeLabel"><%=DateTime.Now %></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
<asp:SqlDataSource ID="DepartmentDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT DepartmentID, Name, GroupName FROM HumanResources.Department ORDER BY Name">
</asp:SqlDataSource>
</div>
</form>
</body>
</html>
Disattivazione dei trigger automatici
I controlli contenuti in un controllo UpdatePanel che generano un postback vengono configurati automaticamente come trigger di tale controllo UpdatePanel. È tuttavia possibile disattivare i trigger automatici e fare in modo che il controllo UpdatePanel possa essere aggiornato esclusivamente tramite un controllo esterno. A tale scopo, impostare la proprietà ChildrenAsTriggers del controllo UpdatePanel su false. Quindi, impostare la proprietà UpdateMode del controllo UpdatePanel su Conditional. Se le proprietà vengono impostate nel modo indicato, il pannello può essere aggiornato solo tramite un controllo esterno o una chiamata al metodo Update.
Nell'esempio seguente sono visualizzate le categorie, le sottocategorie e i nomi dei prodotti contenuti nel database di esempio AdventureWorks. L'elenco delle categorie raramente subisce modifiche e pertanto non occorre aggiornarlo ogni volta che viene visualizzato un elenco di sottocategorie o di prodotti. Di conseguenza, nel controllo UpdatePanel contenente l'elenco delle categorie è possibile impostare la proprietà ChildrenAsTriggers su false e la proprietà UpdateMode su Conditional. Ciò garantisce che il controllo UpdatePanel venga aggiornato soltanto se richiesto in modo esplicito.
<%@ Page Language="VB" AutoEventWireup="true" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head >
<title>UpdatePanel Example</title>
<script >
Protected Sub ProductsUpdatePanel_Load(sender As Object, e As EventArgs)
CategoryTimeLabel.Text = DateTime.Now.ToString()
End Sub
Protected Sub CategoriesRepeater_ItemCommand(sender As Object, e As RepeaterCommandEventArgs)
SubcategoriesDataSource.SelectParameters("CategoryID").DefaultValue = e.CommandArgument.ToString()
SubcategoriesRepeater.DataBind()
ProductsDataSource.SelectParameters("SubcategoryID").DefaultValue = "0"
ProductsGridView.DataBind()
End Sub
Protected Sub SubcategoriesRepeater_ItemCommand(sender As Object, e As RepeaterCommandEventArgs)
ProductsDataSource.SelectParameters("SubcategoryID").DefaultValue = e.CommandArgument.ToString()
ProductsGridView.DataBind()
End Sub
Protected Sub RefreshCategoriesButton_Click(sender As Object, e As EventArgs)
SubcategoriesDataSource.SelectParameters("CategoryID").DefaultValue = "0"
SubcategoriesRepeater.DataBind()
ProductsDataSource.SelectParameters("SubcategoryID").DefaultValue = "0"
ProductsGridView.DataBind()
End Sub
</script>
</head>
<body>
<form id="form1" >
<div>
<asp:ScriptManager ID="ScriptManager1" >
</asp:ScriptManager>
<table>
<tr>
<td valign="top" style="width:120px">
<asp:UpdatePanel ID="ProductsUpdatePanel"
ChildrenAsTriggers="False"
OnLoad="ProductsUpdatePanel_Load" UpdateMode="Conditional">
<ContentTemplate>
<asp:Repeater ID="CategoryRepeater" DataSourceID="CategoriesDataSource"
OnItemCommand="CategoriesRepeater_ItemCommand">
<ItemTemplate>
<asp:LinkButton ID="SelectCategoryButton"
Text='<%# Eval("Name") %>'
CommandName="SelectCategory"
CommandArgument='<%#Eval("ProductCategoryID") %>' /><br />
</ItemTemplate>
</asp:Repeater>
<asp:SqlDataSource ID="CategoriesDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT Name, ProductCategoryID FROM Production.ProductCategory ORDER BY ProductCategoryID">
</asp:SqlDataSource>
<br />
<asp:Label ID="CategoryTimeLabel" Text="Label" Font-Size="Smaller"></asp:Label>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="RefreshCategoriesButton" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
<asp:LinkButton runat="Server" ID="RefreshCategoriesButton" Text="Refresh Category List"
OnClick="RefreshCategoriesButton_Click" Font-Size="smaller" />
</td>
<td valign="top">
<asp:UpdatePanel ID="SubcategoriesUpdatePanel" >
<ContentTemplate>
<asp:Repeater ID="SubcategoriesRepeater" DataSourceID="SubcategoriesDataSource"
OnItemCommand="SubcategoriesRepeater_ItemCommand" >
<ItemTemplate>
<asp:LinkButton ID="SelectSubcategoryButton"
Text='<%# Eval("Name") %>'
CommandName="SelectSubcategory"
CommandArgument='<%#Eval("ProductSubcategoryID") %>' /><br />
</ItemTemplate>
</asp:Repeater>
<asp:SqlDataSource ID="SubcategoriesDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT Name, ProductSubcategoryID FROM Production.ProductSubcategory
WHERE Production.ProductSubcategory.ProductCategoryID = @CategoryID
ORDER BY Name">
<SelectParameters>
<asp:Parameter Name="CategoryID" DefaultValue="0" />
</SelectParameters>
</asp:SqlDataSource>
</ContentTemplate>
</asp:UpdatePanel>
</td>
<td valign="top">
<asp:UpdatePanel ID="ProductUpdatePanel" >
<ContentTemplate>
<asp:GridView ID="ProductsGridView" AllowPaging="True" AutoGenerateColumns="False" BackColor="White" BorderColor="#E7E7FF" BorderStyle="None" BorderWidth="1px" CellPadding="3" DataKeyNames="ProductID" DataSourceID="ProductsDataSource" GridLines="Horizontal">
<FooterStyle BackColor="#B5C7DE" ForeColor="#4A3C8C" />
<Columns>
<asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" >
<ItemStyle Width="240px" />
</asp:BoundField>
</Columns>
<RowStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" />
<SelectedRowStyle BackColor="#738A9C" Font-Bold="True" ForeColor="#F7F7F7" />
<PagerStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" HorizontalAlign="Right" />
<HeaderStyle BackColor="#4A3C8C" Font-Bold="True" ForeColor="#F7F7F7" />
<AlternatingRowStyle BackColor="#F7F7F7" />
</asp:GridView>
<asp:SqlDataSource ID="ProductsDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT ProductID, Name, ProductSubcategoryID FROM Production.Product WHERE (ProductSubcategoryID = @SubcategoryID) ORDER BY Name">
<SelectParameters>
<asp:Parameter DefaultValue="0" Name="SubcategoryID" />
</SelectParameters>
</asp:SqlDataSource>
</ContentTemplate>
</asp:UpdatePanel>
</td>
</tr>
</table>
</div>
</form>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="true" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head >
<title>UpdatePanel Example</title>
<script >
protected void ProductsUpdatePanel_Load(object sender, EventArgs e)
{
CategoryTimeLabel.Text = DateTime.Now.ToString();
}
protected void CategoriesRepeater_ItemCommand(object sender, RepeaterCommandEventArgs e)
{
SubcategoriesDataSource.SelectParameters["CategoryID"].DefaultValue = e.CommandArgument.ToString();
SubcategoriesRepeater.DataBind();
ProductsDataSource.SelectParameters["SubcategoryID"].DefaultValue = "0";
ProductsGridView.DataBind();
}
protected void SubcategoriesRepeater_ItemCommand(object sender, RepeaterCommandEventArgs e)
{
ProductsDataSource.SelectParameters["SubcategoryID"].DefaultValue = e.CommandArgument.ToString();
ProductsGridView.DataBind();
}
protected void RefreshCategoriesButton_Click(object sender, EventArgs e)
{
SubcategoriesDataSource.SelectParameters["CategoryID"].DefaultValue = "0";
SubcategoriesRepeater.DataBind();
ProductsDataSource.SelectParameters["SubcategoryID"].DefaultValue = "0";
ProductsGridView.DataBind();
}
</script>
</head>
<body>
<form id="form1" >
<div>
<asp:ScriptManager ID="ScriptManager1" >
</asp:ScriptManager>
<table>
<tr>
<td valign="top" style="width:120px">
<asp:UpdatePanel ID="ProductsUpdatePanel"
ChildrenAsTriggers="False"
OnLoad="ProductsUpdatePanel_Load" UpdateMode="Conditional">
<ContentTemplate>
<asp:Repeater ID="CategoryRepeater" DataSourceID="CategoriesDataSource"
OnItemCommand="CategoriesRepeater_ItemCommand">
<ItemTemplate>
<asp:LinkButton ID="SelectCategoryButton"
Text='<%# Eval("Name") %>'
CommandName="SelectCategory"
CommandArgument='<%#Eval("ProductCategoryID") %>' /><br />
</ItemTemplate>
</asp:Repeater>
<asp:SqlDataSource ID="CategoriesDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT Name, ProductCategoryID FROM Production.ProductCategory ORDER BY ProductCategoryID">
</asp:SqlDataSource>
<br />
<asp:Label ID="CategoryTimeLabel" Text="Label" Font-Size="Smaller"></asp:Label>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="RefreshCategoriesButton" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
<asp:LinkButton runat="Server" ID="RefreshCategoriesButton" Text="Refresh Category List"
OnClick="RefreshCategoriesButton_Click" Font-Size="smaller" />
</td>
<td valign="top">
<asp:UpdatePanel ID="SubcategoriesUpdatePanel" >
<ContentTemplate>
<asp:Repeater ID="SubcategoriesRepeater" DataSourceID="SubcategoriesDataSource"
OnItemCommand="SubcategoriesRepeater_ItemCommand" >
<ItemTemplate>
<asp:LinkButton ID="SelectSubcategoryButton"
Text='<%# Eval("Name") %>'
CommandName="SelectSubcategory"
CommandArgument='<%#Eval("ProductSubcategoryID") %>' /><br />
</ItemTemplate>
</asp:Repeater>
<asp:SqlDataSource ID="SubcategoriesDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT Name, ProductSubcategoryID FROM Production.ProductSubcategory
WHERE Production.ProductSubcategory.ProductCategoryID = @CategoryID
ORDER BY Name">
<SelectParameters>
<asp:Parameter Name="CategoryID" DefaultValue="0" />
</SelectParameters>
</asp:SqlDataSource>
</ContentTemplate>
</asp:UpdatePanel>
</td>
<td valign="top">
<asp:UpdatePanel ID="ProductUpdatePanel" >
<ContentTemplate>
<asp:GridView ID="ProductsGridView" AllowPaging="True" AutoGenerateColumns="False" BackColor="White" BorderColor="#E7E7FF" BorderStyle="None" BorderWidth="1px" CellPadding="3" DataKeyNames="ProductID" DataSourceID="ProductsDataSource" GridLines="Horizontal">
<FooterStyle BackColor="#B5C7DE" ForeColor="#4A3C8C" />
<Columns>
<asp:BoundField DataField="Name" HeaderText="Name" SortExpression="Name" >
<ItemStyle Width="240px" />
</asp:BoundField>
</Columns>
<RowStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" />
<SelectedRowStyle BackColor="#738A9C" Font-Bold="True" ForeColor="#F7F7F7" />
<PagerStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" HorizontalAlign="Right" />
<HeaderStyle BackColor="#4A3C8C" Font-Bold="True" ForeColor="#F7F7F7" />
<AlternatingRowStyle BackColor="#F7F7F7" />
</asp:GridView>
<asp:SqlDataSource ID="ProductsDataSource" ConnectionString="<%$ ConnectionStrings:AdventureWorksConnectionString %>"
SelectCommand="SELECT ProductID, Name, ProductSubcategoryID FROM Production.Product WHERE (ProductSubcategoryID = @SubcategoryID) ORDER BY Name">
<SelectParameters>
<asp:Parameter DefaultValue="0" Name="SubcategoryID" />
</SelectParameters>
</asp:SqlDataSource>
</ContentTemplate>
</asp:UpdatePanel>
</td>
</tr>
</table>
</div>
</form>
</body>
</html>
Gestione dei trigger e aggiornamento di un controllo UpdatePanel a livello di codice
I controlli che attivano l'aggiornamento di un controllo UpdatePanel devono essere registrati con il controllo ScriptManager della pagina. Ciò si verifica automaticamente per i controlli figlio di un controllo UpdatePanel. I trigger possono essere specificati in modo dichiarativo utilizzando l'insieme Triggers di un controllo UpdatePanel. È inoltre possibile identificare trigger a livello di codice e utilizzare codice server per attivare l'aggiornamento di un controllo UpdatePanel.
Nei casi in cui in fase di progettazione non è disponibile alcun controllo di attivazione, è possibile utilizzare il metodo RegisterAsyncPostBackControl del controllo ScriptManager per registrare il controllo come trigger. I controlli che sono identificati a livello di codice come trigger devono essere registrati a ogni postback. È consigliabile inserire chiamate al metodo RegisterAsyncPostBackControl nell'evento Page_Load della pagina, come mostrato nell'esempio seguente:
Protected Sub Page_Load()
ScriptManager1.RegisterAsyncPostBackControl(SurveyDataList)
End Sub
protected void Page_Load()
{
ScriptManager1.RegisterAsyncPostBackControl(SurveyDataList);
}
Per aggiornare a livello di codice il controllo UpdatePanel è possibile chiamare il metodo Update di un controllo UpdatePanel. Ciò è utile se prima di aggiornare il controllo UpdatePanel occorre eseguire alcune elaborazioni nel server. L'esempio seguente illustra come aggiornare un controllo UpdatePanel a livello di codice.
Protected Sub ChoicesRadioButtonList_SelectedIndexChanged(sender As Object, e As EventArgs)
Dim answers As SortedList = Me.AnsweredQuestions
Dim r As RadioButtonList = CType(sender, RadioButtonList)
answers(r.ToolTip) = r.SelectedValue
Me.AnsweredQuestions = answers
ResultsList.DataSource = Me.AnsweredQuestions
ResultsList.DataBind()
If Me.AnsweredQuestions.Count = SurveyDataList.Items.Count Then _
SubmitButton.Visible = True
UpdatePanel1.Update()
End Sub
protected void ChoicesRadioButtonList_SelectedIndexChanged(object sender, EventArgs e)
{
SortedList answers = this.AnsweredQuestions;
RadioButtonList r = (RadioButtonList)sender;
answers[r.ToolTip] = r.SelectedValue;
this.AnsweredQuestions = answers;
ResultsList.DataSource = this.AnsweredQuestions;
ResultsList.DataBind();
if (this.AnsweredQuestions.Count == SurveyDataList.Items.Count)
SubmitButton.Visible = true;
UpdatePanel1.Update();
}
Nell'esempio seguente viene mostrata una pagina che utilizza il metodo RegisterAsyncPostBackControl per registrare un controllo come trigger. Nell'esempio viene quindi illustrato come utilizzare il metodo Update per aggiornare un controllo UpdatePanel a livello di codice.
<%@ Page Language="VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script >
Protected Property AnsweredQuestions As SortedList
Get
If ViewState("AnsweredQuestions") IsNot Nothing Then
Return CType(ViewState("AnsweredQuestions"), SortedList)
Else
Return New SortedList()
End If
End Get
Set
ViewState("AnsweredQuestions") = value
End Set
End Property
Protected Sub Page_Load()
ScriptManager1.RegisterAsyncPostBackControl(SurveyDataList)
End Sub
Protected Sub ChoicesRadioButtonList_SelectedIndexChanged(sender As Object, e As EventArgs)
Dim answers As SortedList = Me.AnsweredQuestions
Dim r As RadioButtonList = CType(sender, RadioButtonList)
answers(r.ToolTip) = r.SelectedValue
Me.AnsweredQuestions = answers
ResultsList.DataSource = Me.AnsweredQuestions
ResultsList.DataBind()
If Me.AnsweredQuestions.Count = SurveyDataList.Items.Count Then _
SubmitButton.Visible = True
UpdatePanel1.Update()
End Sub
Protected Sub SubmitButton_Click(sender As Object, e As EventArgs)
' Submit responses.
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" >
<title>Registering Controls as Async Postback Controls</title>
<style type="text/css">
.AnswerFloatPanelStyle {
background-color: bisque;
position: absolute;
right: 10px;
height: 130px;
width: 150px;
border-right: silver thin solid; border-top: silver thin solid;
border-left: silver thin solid; border-bottom: silver thin solid;
}
</style>
</head>
<body>
<form id="form1" >
<div>
<asp:ScriptManager ID="ScriptManager1" />
<div id="AnswerFloatPanel" class="AnswerFloatPanelStyle" >
<asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" >
<ContentTemplate>
Completed Questions:
<asp:DataList ID="ResultsList" >
<ItemTemplate>
<asp:Label ID="ResultQuestion" Text='<%# Eval("Key") %>' />
::
<asp:Label ID="ResultAnswer" Text='<%# Eval("Value") %>' />
</ItemTemplate>
</asp:DataList>
<p style="text-align: right">
<asp:Button ID="SubmitButton" Text="Submit" Visible="false"
OnClick="SubmitButton_Click" />
</p>
<asp:Label ID="Message" runat="Server" />
</ContentTemplate>
</asp:UpdatePanel>
</div>
<asp:XmlDataSource ID="SurveyDataSource"
XPath="/Questions/Question"
DataFile="~/App_Data/SurveyQuestions.xml"/>
<asp:DataList
ID="SurveyDataList"
DataSourceID="SurveyDataSource"
>
<ItemTemplate>
<table cellpadding="2" cellspacing="2">
<tr>
<td valign="top">
<asp:Label id="QuestionLabel" Text='<%# XPath("@Title")%>' />
</td>
</tr>
<tr><td>
<asp:RadioButtonList ID="ChoicesRadioButtonList"
DataSource='<%#XPathSelect("Choices/Choice") %>'
DataTextField="InnerText" DataValueField="InnerText"
AutoPostBack="True"
ToolTip='<%# "Question" + XPath("@ID") %>'
OnSelectedIndexChanged="ChoicesRadioButtonList_SelectedIndexChanged"/>
</td></tr>
</table>
<hr />
</ItemTemplate>
</asp:DataList>
</div>
</form>
</body>
</html>
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script >
protected SortedList AnsweredQuestions
{
get { return (SortedList)(ViewState["AnsweredQuestions"] ?? new SortedList()); }
set { ViewState["AnsweredQuestions"] = value; }
}
protected void Page_Load()
{
ScriptManager1.RegisterAsyncPostBackControl(SurveyDataList);
}
protected void ChoicesRadioButtonList_SelectedIndexChanged(object sender, EventArgs e)
{
SortedList answers = this.AnsweredQuestions;
RadioButtonList r = (RadioButtonList)sender;
answers[r.ToolTip] = r.SelectedValue;
this.AnsweredQuestions = answers;
ResultsList.DataSource = this.AnsweredQuestions;
ResultsList.DataBind();
if (this.AnsweredQuestions.Count == SurveyDataList.Items.Count)
SubmitButton.Visible = true;
UpdatePanel1.Update();
}
protected void SubmitButton_Click(object sender, EventArgs e)
{
// Submit responses.
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" >
<title>Registering Controls as Async Postback Controls</title>
<style type="text/css">
.AnswerFloatPanelStyle {
background-color: bisque;
position: absolute;
right: 10px;
height: 130px;
width: 150px;
border-right: silver thin solid; border-top: silver thin solid;
border-left: silver thin solid; border-bottom: silver thin solid;
}
</style>
</head>
<body>
<form id="form1" >
<div>
<asp:ScriptManager ID="ScriptManager1" />
<div id="AnswerFloatPanel" class="AnswerFloatPanelStyle" >
<asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" >
<ContentTemplate>
Completed Questions:
<asp:DataList ID="ResultsList" >
<ItemTemplate>
<asp:Label ID="ResultQuestion" Text='<%# Eval("Key") %>' />
::
<asp:Label ID="ResultAnswer" Text='<%# Eval("Value") %>' />
</ItemTemplate>
</asp:DataList>
<p style="text-align: right">
<asp:Button ID="SubmitButton" Text="Submit" Visible="false"
OnClick="SubmitButton_Click" />
</p>
<asp:Label ID="Message" runat="Server" />
</ContentTemplate>
</asp:UpdatePanel>
</div>
<asp:XmlDataSource ID="SurveyDataSource"
XPath="/Questions/Question"
DataFile="~/App_Data/SurveyQuestions.xml"/>
<asp:DataList
ID="SurveyDataList"
DataSourceID="SurveyDataSource"
>
<ItemTemplate>
<table cellpadding="2" cellspacing="2">
<tr>
<td valign="top">
<asp:Label id="QuestionLabel" Text='<%# XPath("@Title")%>' />
</td>
</tr>
<tr><td>
<asp:RadioButtonList ID="ChoicesRadioButtonList"
DataSource='<%#XPathSelect("Choices/Choice") %>'
DataTextField="InnerText" DataValueField="InnerText"
AutoPostBack="True"
ToolTip='<%# "Question" + XPath("@ID") %>'
OnSelectedIndexChanged="ChoicesRadioButtonList_SelectedIndexChanged"/>
</td></tr>
</table>
<hr />
</ItemTemplate>
</asp:DataList>
</div>
</form>
</body>
</html>
Attivazione del rendering a pagina parziale in un controllo personalizzato
È possibile aggiungere un controllo UpdatePanel a un controllo utente o a un controllo personalizzato. È tuttavia possibile che nella pagina che contiene tale controllo non sia presente alcun controllo ScriptManager avente la proprietà EnablePartialRendering impostata su true. Per determinare se nel controllo personalizzato è attivo il rendering a pagina parziale è possibile chiamare il metodo statico GetCurrent del controllo ScriptManager. Se la pagina non contiene alcun controllo ScriptManager, il metodo GetCurrent restituisce null. In caso contrario, è possibile verificare il valore della proprietà EnablePartialRendering del controllo ScriptManager e includere un controllo UpdatePanel se la proprietà EnablePartialRendering risulta essere true.
L'esempio seguente illustra il metodo CreateChildControls di un controllo personalizzato che eredita dalla classe CompositeControl. Se nella pagina è attivo il rendering a pagina parziale, il controllo personalizzato inserisce il proprio contenuto in un controllo UpdatePanel.
Protected Overrides Sub CreateChildControls()
MyBase.CreateChildControls()
Dim parent As Control
Dim container As Control
' Get a reference to the ScriptManager object for the page
' if one exists.
Dim sm As ScriptManager = ScriptManager.GetCurrent(Page)
If sm Is Nothing OrElse Not sm.EnablePartialRendering Then
' If partial rendering is not enabled, set the parent
' and container as a basic control.
container = New Control()
parent = container
Else
' If partial rendering is enabled, set the parent as
' a new UpdatePanel object and the container to the
' content template of the UpdatePanel object.
Dim up As UpdatePanel = New UpdatePanel()
container = up.ContentTemplateContainer
parent = up
End If
AddDataboundControls(container)
Controls.Add(parent)
End Sub
protected override void CreateChildControls() {
base.CreateChildControls();
Control parent;
Control container;
// Get a reference to the ScriptManager object for the page
// if one exists.
ScriptManager sm = ScriptManager.GetCurrent(Page);
if (sm == null || !sm.EnablePartialRendering)
{
// If partial rendering is not enabled, set the parent
// and container as a basic control.
container = new Control();
parent = container;
}
else
{
// If partial rendering is enabled, set the parent as
// a new UpdatePanel object and the container to the
// content template of the UpdatePanel object.
UpdatePanel up = new UpdatePanel();
container = up.ContentTemplateContainer;
parent = up;
}
AddDataboundControls(container);
Controls.Add(parent);
}
Nell'esempio seguente viene mostrato un controllo personalizzato che, se è attivo il rendering a pagina parziale, include un controllo UpdatePanel.
<%@ Page Language="VB" AutoEventWireup="true" %>
<%@ Register Namespace="UpdatePanelTutorialCustom.VB" TagPrefix="sample" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" >
<title>Browse Products</title>
<script >
Protected Sub ProductsView1_RowCommand(ByVal sender As Object, ByVal e As EventArgs)
ShoppingCartList.DataSource = ProductsView1.Cart
ShoppingCartList.DataBind()
End Sub
</script>
</head>
<body>
<form id="form1" >
<div>
<asp:ScriptManager ID="ScriptManager1" EnablePartialRendering="false" />
<h2>Browse Products</h2>
<sample:ProductsView ID="ProductsView1" PageSize="5" OnRowCommand="ProductsView1_RowCommand" />
<asp:UpdatePanel ID="CartUpdatePanel">
<ContentTemplate>
<h3>Selected Items</h3>
<asp:BulletedList BulletStyle="numbered" ID="ShoppingCartList" />
</ContentTemplate>
</asp:UpdatePanel>
</div>
</form>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="true" %>
<%@ Register Namespace="UpdatePanelTutorialCustom.CS" TagPrefix="sample" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head >
<title>Browse Products</title>
<script >
protected void ProductsView1_RowCommand(object sender, EventArgs e)
{
ShoppingCartList.DataSource = ProductsView1.Cart;
ShoppingCartList.DataBind();
}
</script>
</head>
<body>
<form id="form1" >
<div>
<asp:ScriptManager ID="ScriptManager1" EnablePartialRendering="false" />
<h2>Browse Products</h2>
<sample:ProductsView ID="ProductsView1" PageSize="5" OnRowCommand="ProductsView1_RowCommand" />
<asp:UpdatePanel ID="CartUpdatePanel">
<ContentTemplate>
<h3>Selected Items</h3>
<asp:BulletedList BulletStyle="numbered" ID="ShoppingCartList" />
</ContentTemplate>
</asp:UpdatePanel>
</div>
</form>
</body>
</html>
Imports System
Imports System.Data
Imports System.Configuration
Imports System.Collections
Imports System.Web
Imports System.Web.Security
Imports System.Web.UI.WebControls
Imports System.Web.UI.WebControls.WebParts
Imports System.Web.UI.HtmlControls
Imports System.Web.UI
Imports System.Drawing
Namespace UpdatePanelTutorialCustom.VB
Public Class ProductsView
Inherits CompositeControl
Private _pageSize As Integer
Private _cart As ArrayList
Private Shared ReadOnly EventRowCommand As Object = New Object()
Public Property PageSize() As Integer
Get
Return _pageSize
End Get
Set(ByVal value As Integer)
_pageSize = value
End Set
End Property
Public ReadOnly Property Cart() As ArrayList
Get
Return _cart
End Get
End Property
Protected Overrides Sub CreateChildControls()
MyBase.CreateChildControls()
Dim parent As Control
Dim container As Control
' Get a reference to the ScriptManager object for the page
' if one exists.
Dim sm As ScriptManager = ScriptManager.GetCurrent(Page)
If sm Is Nothing OrElse Not sm.EnablePartialRendering Then
' If partial rendering is not enabled, set the parent
' and container as a basic control.
container = New Control()
parent = container
Else
' If partial rendering is enabled, set the parent as
' a new UpdatePanel object and the container to the
' content template of the UpdatePanel object.
Dim up As UpdatePanel = New UpdatePanel()
container = up.ContentTemplateContainer
parent = up
End If
AddDataboundControls(container)
Controls.Add(parent)
End Sub
Private Sub GridView_RowCommand(ByVal sender As Object, ByVal e As GridViewCommandEventArgs)
Dim productID As String
If e.CommandName = "AddToCart" Then
productID = CType(sender, GridView).DataKeys(Convert.ToInt32(e.CommandArgument)).Value.ToString()
If _cart Is Nothing Then GetCart()
If _cart.IndexOf(productID) = -1 Then _
_cart.Add(productID)
ViewState("Cart") = _cart
End If
If e.CommandName = "RemoveFromCart" Then
productID = CType(sender, GridView).DataKeys(Convert.ToInt32(e.CommandArgument)).Value.ToString()
If _cart Is Nothing Then GetCart()
_cart.Remove(productID)
ViewState("Cart") = _cart
End If
Me.OnRowCommand(New EventArgs())
End Sub
Private Sub GetCart()
If ViewState("Cart") Is Nothing Then
_cart = New ArrayList()
Else
_cart = CType(ViewState("Cart"), ArrayList)
End If
End Sub
Custom Event RowCommand As EventHandler
RaiseEvent(ByVal sender As Object, ByVal e As EventArgs)
End RaiseEvent
AddHandler(ByVal value As EventHandler)
Events.AddHandler(EventRowCommand, value)
End AddHandler
RemoveHandler(ByVal value As EventHandler)
Events.RemoveHandler(EventRowCommand, value)
End RemoveHandler
End Event
Protected Overridable Sub OnRowCommand(ByVal e As EventArgs)
Dim handler As EventHandler = CType(Events(EventRowCommand), EventHandler)
If handler IsNot Nothing Then
handler(Me, e)
End If
End Sub
Private Sub AddDataboundControls(ByVal parent As Control)
Dim ds As SqlDataSource = New SqlDataSource()
ds.ID = "ProductsSqlDataSource"
ds.ConnectionString = _
ConfigurationManager.ConnectionStrings("AdventureWorksConnectionString").ConnectionString
ds.SelectCommand = _
"SELECT Production.ProductDescription.Description, Production.Product.Name, Production.ProductPhoto.ThumbnailPhotoFileName, " & _
"Production.Product.ProductID " & _
"FROM Production.Product INNER JOIN " & _
"Production.ProductProductPhoto ON Production.Product.ProductID = Production.ProductProductPhoto.ProductID INNER JOIN " & _
"Production.ProductPhoto ON Production.ProductProductPhoto.ProductPhotoID = Production.ProductPhoto.ProductPhotoID INNER JOIN " & _
"Production.ProductModelProductDescriptionCulture ON " & _
"Production.Product.ProductModelID = Production.ProductModelProductDescriptionCulture.ProductModelID INNER JOIN " & _
"Production.ProductDescription ON " & _
"Production.ProductModelProductDescriptionCulture.ProductDescriptionID = Production.ProductDescription.ProductDescriptionID"
Dim gv As GridView = New GridView()
gv.ID = "ProductsGridView"
gv.DataSourceID = ds.ID
gv.AutoGenerateColumns = False
gv.DataKeyNames = New String() {"ProductID"}
gv.GridLines = GridLines.None
gv.HeaderStyle.BackColor = Color.LightGray
gv.AlternatingRowStyle.BackColor = Color.LightBlue
gv.AllowPaging = True
gv.PageSize = _pageSize
AddHandler gv.RowCommand, AddressOf Me.GridView_RowCommand
Dim if1 As ImageField = New ImageField()
if1.HeaderText = "Product"
if1.DataImageUrlField = "ThumbnailPhotoFileName"
if1.DataImageUrlFormatString = "..\images\thumbnails\{0}"
Dim bf1 As BoundField = New BoundField()
bf1.HeaderText = "Name"
bf1.DataField = "Name"
Dim bf2 As BoundField = New BoundField()
bf2.HeaderText = "Description"
bf2.DataField = "Description"
Dim btf1 As ButtonField = New ButtonField()
btf1.Text = "Add"
btf1.CommandName = "AddToCart"
Dim btf2 As ButtonField = New ButtonField()
btf2.Text = "Remove"
btf2.CommandName = "RemoveFromCart"
gv.Columns.Add(if1)
gv.Columns.Add(bf1)
gv.Columns.Add(bf2)
gv.Columns.Add(btf1)
gv.Columns.Add(btf2)
parent.Controls.Add(New LiteralControl("<br />"))
parent.Controls.Add(gv)
parent.Controls.Add(New LiteralControl("<br />"))
parent.Controls.Add(ds)
End Sub
End Class
End Namespace
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Web.UI;
using System.Drawing;
namespace UpdatePanelTutorialCustom.CS
{
public class ProductsView : CompositeControl
{
private int _pageSize;
private ArrayList _cart;
private static readonly object EventRowCommand = new object();
public int PageSize
{
get { return _pageSize; }
set { _pageSize = value; }
}
public ArrayList Cart
{
get { return _cart; }
}
protected override void CreateChildControls() {
base.CreateChildControls();
Control parent;
Control container;
// Get a reference to the ScriptManager object for the page
// if one exists.
ScriptManager sm = ScriptManager.GetCurrent(Page);
if (sm == null || !sm.EnablePartialRendering)
{
// If partial rendering is not enabled, set the parent
// and container as a basic control.
container = new Control();
parent = container;
}
else
{
// If partial rendering is enabled, set the parent as
// a new UpdatePanel object and the container to the
// content template of the UpdatePanel object.
UpdatePanel up = new UpdatePanel();
container = up.ContentTemplateContainer;
parent = up;
}
AddDataboundControls(container);
Controls.Add(parent);
}
private void GridView_RowCommand(object sender, GridViewCommandEventArgs e)
{
string productID;
if (e.CommandName == "AddToCart")
{
productID = ((GridView)sender).DataKeys[Convert.ToInt32(e.CommandArgument)].Value.ToString();
if (_cart == null) { GetCart(); }
if (_cart.IndexOf(productID) == -1)
_cart.Add(productID);
ViewState["Cart"] = _cart;
}
if (e.CommandName == "RemoveFromCart")
{
productID = ((GridView)sender).DataKeys[Convert.ToInt32(e.CommandArgument)].Value.ToString();
if (_cart == null) { GetCart(); }
_cart.Remove(productID);
ViewState["Cart"] = _cart;
}
this.OnRowCommand(new EventArgs());
}
private void GetCart()
{
if (ViewState["Cart"] == null)
_cart = new ArrayList();
else
_cart = (ArrayList)ViewState["Cart"];
}
public event EventHandler RowCommand
{
add { Events.AddHandler(EventRowCommand, value); }
remove { Events.RemoveHandler(EventRowCommand, value); }
}
protected virtual void OnRowCommand(EventArgs e)
{
EventHandler handler = (EventHandler)Events[EventRowCommand];
if (handler != null)
{
handler(this, e);
}
}
private void AddDataboundControls(Control parent)
{
SqlDataSource ds = new SqlDataSource();
ds.ID = "ProductsSqlDataSource";
ds.ConnectionString =
ConfigurationManager.ConnectionStrings["AdventureWorksConnectionString"].ConnectionString;
ds.SelectCommand =
"SELECT Production.ProductDescription.Description, Production.Product.Name, Production.ProductPhoto.ThumbnailPhotoFileName, " +
"Production.Product.ProductID " +
"FROM Production.Product INNER JOIN " +
"Production.ProductProductPhoto ON Production.Product.ProductID = Production.ProductProductPhoto.ProductID INNER JOIN " +
"Production.ProductPhoto ON Production.ProductProductPhoto.ProductPhotoID = Production.ProductPhoto.ProductPhotoID INNER JOIN " +
"Production.ProductModelProductDescriptionCulture ON " +
"Production.Product.ProductModelID = Production.ProductModelProductDescriptionCulture.ProductModelID INNER JOIN " +
"Production.ProductDescription ON " +
"Production.ProductModelProductDescriptionCulture.ProductDescriptionID = Production.ProductDescription.ProductDescriptionID";
GridView gv = new GridView();
gv.ID = "ProductsGridView";
gv.DataSourceID = ds.ID;
gv.AutoGenerateColumns = false;
gv.DataKeyNames = new string[] { "ProductID" };
gv.GridLines = GridLines.None;
gv.HeaderStyle.BackColor = Color.LightGray;
gv.AlternatingRowStyle.BackColor = Color.LightBlue;
gv.AllowPaging = true;
gv.PageSize = _pageSize;
gv.RowCommand += this.GridView_RowCommand;
ImageField if1 = new ImageField();
if1.HeaderText = "Product";
if1.DataImageUrlField = "ThumbnailPhotoFileName";
if1.DataImageUrlFormatString = @"..\images\thumbnails\{0}";
BoundField bf1 = new BoundField();
bf1.HeaderText = "Name";
bf1.DataField = "Name";
BoundField bf2 = new BoundField();
bf2.HeaderText = "Description";
bf2.DataField = "Description";
ButtonField btf1 = new ButtonField();
btf1.Text = "Add";
btf1.CommandName = "AddToCart";
ButtonField btf2 = new ButtonField();
btf2.Text = "Remove";
btf2.CommandName = "RemoveFromCart";
gv.Columns.Add(if1);
gv.Columns.Add(bf1);
gv.Columns.Add(bf2);
gv.Columns.Add(btf1);
gv.Columns.Add(btf2);
parent.Controls.Add(new LiteralControl("<br />"));
parent.Controls.Add(gv);
parent.Controls.Add(new LiteralControl("<br />"));
parent.Controls.Add(ds);
}
}
}
Vedere anche
Concetti
Cenni preliminari sul rendering a pagina parziale