ListView.ItemCanceling Událost
Definice
Důležité
Některé informace platí pro předběžně vydaný produkt, který se může zásadně změnit, než ho výrobce nebo autor vydá. Microsoft neposkytuje žádné záruky, výslovné ani předpokládané, týkající se zde uváděných informací.
Nastane, když je požadována operace zrušení, ale předtím, než ListView ovládací prvek zruší operaci vložení nebo úpravy.
public:
event EventHandler<System::Web::UI::WebControls::ListViewCancelEventArgs ^> ^ ItemCanceling;public event EventHandler<System.Web.UI.WebControls.ListViewCancelEventArgs> ItemCanceling;member this.ItemCanceling : EventHandler<System.Web.UI.WebControls.ListViewCancelEventArgs> Public Custom Event ItemCanceling As EventHandler(Of ListViewCancelEventArgs) Event Type
Příklady
Následující příklad ukazuje, jak vytvořit obslužnou rutinu ItemCanceling události.
Důležité
Tento příklad obsahuje textová pole, která přijímají vstup uživatele, což je potenciální bezpečnostní hrozba. Ve výchozím nastavení ASP.NET webové stránky ověřují, že uživatelský vstup neobsahuje skript nebo elementy HTML. Další informace najdete v tématu Přehled zneužití skriptů.
<%@ 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()
{
Message.Text = String.Empty;
}
// <Snippet2>
protected void ContactsListView_ItemCanceling(object sender, ListViewCancelEventArgs e)
{
//Check the operation that raised the event
if (e.CancelMode == ListViewCancelMode.CancelingEdit)
{
// The update operation was canceled. Display the
// primary key of the item.
Message.Text = "Update for the ContactID " +
ContactsListView.DataKeys[e.ItemIndex].Value.ToString() + " canceled.";
}
else
{
Message.Text = "Insert operation canceled.";
}
}
// </Snippet2>
protected void ContactsListView_PagePropertiesChanging(object sender,
PagePropertiesChangingEventArgs e)
{
// Clears the edit index selection when paging.
ContactsListView.EditIndex = -1;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>ListView ItemCanceling Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>ListView ItemCanceling Example</h3>
<asp:Label ID="Message"
ForeColor="Red"
runat="server"/>
<br/>
<asp:ListView ID="ContactsListView"
DataSourceID="ContactsDataSource"
DataKeyNames="ContactID"
ConvertEmptyStringToNull="true"
InsertItemPosition="LastItem"
runat="server"
OnItemCanceling="ContactsListView_ItemCanceling"
OnPagePropertiesChanging="ContactsListView_PagePropertiesChanging" >
<LayoutTemplate>
<table cellpadding="2" width="680px" border="1" runat="server" id="tblContacts">
<tr runat="server">
<th runat="server"> </th>
<th runat="server">ID</th>
<th runat="server">First Name</th>
<th runat="server">Last Name</th>
<th runat="server">Email Address</th>
</tr>
<tr runat="server" id="itemPlaceholder" />
</table>
<asp:DataPager runat="server" ID="ContactsDataPager" PageSize="12">
<Fields>
<asp:NextPreviousPagerField
ShowFirstPageButton="true" ShowLastPageButton="true"
FirstPageText="|<< " LastPageText=" >>|"
NextPageText=" > " PreviousPageText=" < " />
</Fields>
</asp:DataPager>
</LayoutTemplate>
<ItemTemplate>
<tr runat="server">
<td valign="top">
<asp:LinkButton ID="EditButton" runat="server" Text="Edit" CommandName="Edit" /><br />
</td>
<td valign="top">
<asp:Label ID="Label1" runat="server" Text='<%#Eval("ContactID") %>' />
</td>
<td valign="top">
<asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("FirstName") %>' />
</td>
<td valign="top">
<asp:Label ID="LastNameLabel" runat="server" Text='<%#Eval("LastName") %>' />
</td>
<td valign="top">
<asp:Label ID="EmailAddressLabel" runat="server" Text='<%#Eval("EmailAddress") %>' />
</td>
</tr>
</ItemTemplate>
<EditItemTemplate>
<tr style="background-color: #ADD8E6">
<td valign="top">
<asp:LinkButton ID="UpdateButton" runat="server" CommandName="Update" Text="Update" /><br />
<asp:LinkButton ID="CancelEditButton" runat="server" CommandName="Cancel" Text="Cancel" />
</td>
<td>
<asp:Label ID="Label1" runat="server" Text='<%#Eval("ContactID") %>' />
</td>
<td>
<asp:TextBox ID="FirstNameTextBox" runat="server"
Text='<%#Bind("FirstName") %>' MaxLength="50" /><br />
</td>
<td>
<asp:TextBox ID="LastNameTextBox" runat="server"
Text='<%#Bind("LastName") %>' MaxLength="50" /><br />
</td>
<td>
<asp:TextBox ID="EmailAddressTextBox" runat="server"
Text='<%#Bind("EmailAddress") %>' MaxLength="50" /><br />
</td>
</tr>
</EditItemTemplate>
<InsertItemTemplate>
<tr style="background-color:#90EE90">
<td colspan="2">
<asp:LinkButton ID="InsertButton" runat="server" CommandName="Insert" Text="Insert" /><br />
<asp:LinkButton ID="CancelInsertButton" runat="server" CommandName="Cancel" Text="Cancel" />
</td>
<td>
<asp:TextBox ID="FirstNameITextBox" runat="server"
Text='<%#Bind("FirstName") %>' MaxLength="50" />
</td>
<td>
<asp:TextBox ID="LastNameITextBox" runat="server"
Text='<%#Bind("LastName") %>' MaxLength="50" />
</td>
<td>
<asp:TextBox ID="EmailAddressITextBox" runat="server"
Text='<%#Bind("EmailAddress") %>' MaxLength="50" />
</td>
</tr>
</InsertItemTemplate>
</asp:ListView>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the AdventureWorks sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:SqlDataSource ID="ContactsDataSource" runat="server"
ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
SelectCommand="SELECT [ContactID], [FirstName], [LastName], [EmailAddress] FROM Person.Contact"
InsertCommand="INSERT INTO Person.Contact
([FirstName], [LastName], [EmailAddress], [PasswordHash], [PasswordSalt])
Values(@FirstName, @LastName, @EmailAddress, '', '')"
UpdateCommand="UPDATE Person.Contact
SET FirstName = @FirstName, LastName = @LastName,
EmailAddress = @EmailAddress
WHERE ContactID = @ContactID">
</asp:SqlDataSource>
</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()
Message.Text = String.Empty
End Sub
' <Snippet2>
Protected Sub ContactsListView_ItemCanceling(ByVal sender As Object, _
ByVal e As ListViewCancelEventArgs)
'Check the operation that raised the event
If (e.CancelMode = ListViewCancelMode.CancelingEdit) Then
' The update operation was canceled. Display the
' primary key of the item.
Message.Text = "Update for the ContactID " & _
ContactsListView.DataKeys(e.ItemIndex).Value.ToString() & " canceled."
Else
Message.Text = "Insert operation canceled."
End If
End Sub
' </Snippet2>
Protected Sub ContactsListView_PagePropertiesChanging(ByVal sender As Object, _
ByVal e As PagePropertiesChangingEventArgs)
' Clears the edit index selection when paging.
ContactsListView.EditIndex = -1
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>ListView ItemCanceling Example</title>
</head>
<body>
<form id="form1" runat="server">
<h3>ListView ItemCanceling Example</h3>
<asp:Label ID="Message"
ForeColor="Red"
runat="server"/>
<br/>
<asp:ListView ID="ContactsListView"
DataSourceID="ContactsDataSource"
DataKeyNames="ContactID"
ConvertEmptyStringToNull="true"
InsertItemPosition="LastItem"
runat="server"
OnItemCanceling="ContactsListView_ItemCanceling"
OnPagePropertiesChanging="ContactsListView_PagePropertiesChanging" >
<LayoutTemplate>
<table cellpadding="2" width="680px" border="1" runat="server" id="tblContacts">
<tr runat="server">
<th runat="server"> </th>
<th runat="server">ID</th>
<th runat="server">First Name</th>
<th runat="server">Last Name</th>
<th runat="server">Email Address</th>
</tr>
<tr runat="server" id="itemPlaceholder" />
</table>
<asp:DataPager runat="server" ID="ContactsDataPager" PageSize="12">
<Fields>
<asp:NextPreviousPagerField
ShowFirstPageButton="true" ShowLastPageButton="true"
FirstPageText="|<< " LastPageText=" >>|"
NextPageText=" > " PreviousPageText=" < " />
</Fields>
</asp:DataPager>
</LayoutTemplate>
<ItemTemplate>
<tr runat="server">
<td valign="top">
<asp:LinkButton ID="EditButton" runat="server" Text="Edit" CommandName="Edit" /><br />
</td>
<td valign="top">
<asp:Label ID="Label1" runat="server" Text='<%#Eval("ContactID") %>' />
</td>
<td valign="top">
<asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("FirstName") %>' />
</td>
<td valign="top">
<asp:Label ID="LastNameLabel" runat="server" Text='<%#Eval("LastName") %>' />
</td>
<td valign="top">
<asp:Label ID="EmailAddressLabel" runat="server" Text='<%#Eval("EmailAddress") %>' />
</td>
</tr>
</ItemTemplate>
<EditItemTemplate>
<tr style="background-color: #ADD8E6">
<td valign="top">
<asp:LinkButton ID="UpdateButton" runat="server" CommandName="Update" Text="Update" /><br />
<asp:LinkButton ID="CancelEditButton" runat="server" CommandName="Cancel" Text="Cancel" />
</td>
<td>
<asp:Label ID="Label1" runat="server" Text='<%#Eval("ContactID") %>' />
</td>
<td>
<asp:TextBox ID="FirstNameTextBox" runat="server"
Text='<%#Bind("FirstName") %>' MaxLength="50" /><br />
</td>
<td>
<asp:TextBox ID="LastNameTextBox" runat="server"
Text='<%#Bind("LastName") %>' MaxLength="50" /><br />
</td>
<td>
<asp:TextBox ID="EmailAddressTextBox" runat="server"
Text='<%#Bind("EmailAddress") %>' MaxLength="50" /><br />
</td>
</tr>
</EditItemTemplate>
<InsertItemTemplate>
<tr style="background-color:#90EE90">
<td colspan="2">
<asp:LinkButton ID="InsertButton" runat="server" CommandName="Insert" Text="Insert" /><br />
<asp:LinkButton ID="CancelInsertButton" runat="server" CommandName="Cancel" Text="Cancel" />
</td>
<td>
<asp:TextBox ID="FirstNameITextBox" runat="server"
Text='<%#Bind("FirstName") %>' MaxLength="50" />
</td>
<td>
<asp:TextBox ID="LastNameITextBox" runat="server"
Text='<%#Bind("LastName") %>' MaxLength="50" />
</td>
<td>
<asp:TextBox ID="EmailAddressITextBox" runat="server"
Text='<%#Bind("EmailAddress") %>' MaxLength="50" />
</td>
</tr>
</InsertItemTemplate>
</asp:ListView>
<!-- This example uses Microsoft SQL Server and connects -->
<!-- to the AdventureWorks sample database. Use an ASP.NET -->
<!-- expression to retrieve the connection string value -->
<!-- from the Web.config file. -->
<asp:SqlDataSource ID="ContactsDataSource" runat="server"
ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
SelectCommand="SELECT [ContactID], [FirstName], [LastName], [EmailAddress] FROM Person.Contact"
InsertCommand="INSERT INTO Person.Contact
([FirstName], [LastName], [EmailAddress], [PasswordHash], [PasswordSalt])
Values(@FirstName, @LastName, @EmailAddress, '', '')"
UpdateCommand="UPDATE Person.Contact
SET FirstName = @FirstName, LastName = @LastName,
EmailAddress = @EmailAddress
WHERE ContactID = @ContactID">
</asp:SqlDataSource>
</form>
</body>
</html>
Poznámky
Ovládací ListView prvek vyvolá ItemCanceling událost, když kliknete na tlačítko Zrušit v InsertItemTemplate šabloně nebo EditItemTemplate předtím, než ListView ovládací prvek zruší operaci vložení nebo úpravy. (Tlačítko Zrušit je ovládací prvek tlačítka, jehož CommandName vlastnost je nastavená na Zrušit.) To vám umožní provést vlastní rutinu pokaždé, když dojde k této události, například zastavení operace zrušení, pokud by se položka dostala do nežádoucího stavu.
Objekt ListViewCancelEventArgs je předán obslužné rutině události, která umožňuje určit index položky. Umožňuje také označit, že operace zrušení by měla být zastavena. Pokud chcete operaci zastavit, nastavte Cancel vlastnost objektu ListViewCancelEventArgs na true.
Další informace o zpracování událostí najdete v tématu Zpracování a vyvolávání událostí.
Platí pro
Viz také
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Zdroj tohoto obsahu najdete na GitHubu, kde můžete také vytvářet a kontrolovat problémy a žádosti o přijetí změn. Další informace najdete v našem průvodci pro přispěvatele.
