ListView.ItemDeleting Event
Definition
Important
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Occurs when a delete operation is requested, but before the ListView control deletes the item.
public:
event EventHandler<System::Web::UI::WebControls::ListViewDeleteEventArgs ^> ^ ItemDeleting;public event EventHandler<System.Web.UI.WebControls.ListViewDeleteEventArgs> ItemDeleting;member this.ItemDeleting : EventHandler<System.Web.UI.WebControls.ListViewDeleteEventArgs> Public Custom Event ItemDeleting As EventHandler(Of ListViewDeleteEventArgs) Event Type
Examples
The following example shows how to declaratively add an event handler for the ItemDeleting event.
<%@ 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">
protected void CategoriesListView_OnItemDeleting(object sender, ListViewDeleteEventArgs e)
{
if (SubCategoriesGridView.Rows.Count > 0)
{
MessageLabel.Text = "You cannot delete a category that has sub-categories.";
e.Cancel = true;
}
}
protected void Page_Load()
{
MessageLabel.Text = String.Empty;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Subcategories List</title>
</head>
<body>
<form id="form1" runat="server">
<b>Categories</b>
<br />
<asp:Label ForeColor="Red" runat="server" ID="MessageLabel" /><br />
<asp:ListView runat="server"
ID="CategoriesListView"
OnItemDeleting="CategoriesListView_OnItemDeleting"
DataSourceID="CategoriesDataSource"
DataKeyNames="ProductCategoryID">
<LayoutTemplate>
<table runat="server" id="tblCategories"
cellspacing="0" cellpadding="1" width="440px" border="1">
<tr id="itemPlaceholder" runat="server"></tr>
</table>
</LayoutTemplate>
<ItemTemplate>
<tr runat="server">
<td>
<asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
</td>
<td style="width:40px">
<asp:LinkButton runat="server" ID="SelectCategoryButton"
Text="Select" CommandName="Select" />
</td>
</tr>
</ItemTemplate>
<SelectedItemTemplate>
<tr runat="server" style="background-color:#90EE90">
<td>
<asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
</td>
<td style="width:40px">
<asp:LinkButton runat="server" ID="SelectCategoryButton"
Text="Delete" CommandName="Delete" />
</td>
</tr>
</SelectedItemTemplate>
</asp:ListView>
<br />
<b>Subcategories</b>
<asp:GridView runat="server" ID="SubCategoriesGridView" Width="300px"
DataSourceID="SubCategoriesDataSource" DataKeyNames="ProductSubcategoryID"
AutoGenerateColumns="True" />
<!-- 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="CategoriesDataSource" runat="server"
ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
SelectCommand="SELECT [ProductCategoryID], [Name]
FROM Production.ProductCategory">
</asp:SqlDataSource>
<asp:SqlDataSource ID="SubCategoriesDataSource" runat="server"
ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
SelectCommand="SELECT [ProductSubcategoryID], [Name]
FROM Production.ProductSubcategory
WHERE ProductCategoryID = @ProductCategoryID
ORDER BY [Name]">
<SelectParameters>
<asp:ControlParameter Name="ProductCategoryID" DefaultValue="0"
ControlID="CategoriesListView" PropertyName="SelectedValue" />
</SelectParameters>
</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">
Protected Sub CategoriesListView_OnItemDeleting(sender As Object, e As ListViewDeleteEventArgs)
If SubCategoriesGridView.Rows.Count > 0 Then
MessageLabel.Text = "You cannot delete a category that has sub-categories."
e.Cancel = True
End If
End Sub
Protected Sub Page_Load()
MessageLabel.Text = String.Empty
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Subcategories List</title>
</head>
<body>
<form id="form1" runat="server">
<b>Categories</b>
<br />
<asp:Label ForeColor="Red" runat="server" ID="MessageLabel" /><br />
<asp:ListView runat="server"
ID="CategoriesListView"
OnItemDeleting="CategoriesListView_OnItemDeleting"
DataSourceID="CategoriesDataSource"
DataKeyNames="ProductCategoryID">
<LayoutTemplate>
<table runat="server" id="tblCategories"
cellspacing="0" cellpadding="1" width="440px" border="1">
<tr id="itemPlaceholder" runat="server"></tr>
</table>
</LayoutTemplate>
<ItemTemplate>
<tr runat="server">
<td>
<asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
</td>
<td style="width:40px">
<asp:LinkButton runat="server" ID="SelectCategoryButton"
Text="Select" CommandName="Select" />
</td>
</tr>
</ItemTemplate>
<SelectedItemTemplate>
<tr runat="server" style="background-color:#90EE90">
<td>
<asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
</td>
<td style="width:40px">
<asp:LinkButton runat="server" ID="SelectCategoryButton"
Text="Delete" CommandName="Delete" />
</td>
</tr>
</SelectedItemTemplate>
</asp:ListView>
<br />
<b>Subcategories</b>
<asp:GridView runat="server" ID="SubCategoriesGridView" Width="300px"
DataSourceID="SubCategoriesDataSource" DataKeyNames="ProductSubcategoryID"
AutoGenerateColumns="True" />
<!-- 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="CategoriesDataSource" runat="server"
ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
SelectCommand="SELECT [ProductCategoryID], [Name]
FROM Production.ProductCategory">
</asp:SqlDataSource>
<asp:SqlDataSource ID="SubCategoriesDataSource" runat="server"
ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
SelectCommand="SELECT [ProductSubcategoryID], [Name]
FROM Production.ProductSubcategory
WHERE ProductCategoryID = @ProductCategoryID
ORDER BY [Name]">
<SelectParameters>
<asp:ControlParameter Name="ProductCategoryID" DefaultValue="0"
ControlID="CategoriesListView" PropertyName="SelectedValue" />
</SelectParameters>
</asp:SqlDataSource>
</form>
</body>
</html>
Remarks
The ItemDeleting event is raised when an item's Delete button is clicked or the DeleteItem method is called, but before the ListView control deletes the item. (A Delete button is a button control whose CommandName property is set to "Delete".) This enables you to perform a custom routine whenever this event occurs, such as canceling the delete operation.
A ListViewDeleteEventArgs object is passed to the event handler, which enables you to determine the index of the current item. It also lets you indicate that the delete operation should be canceled. To cancel the delete operation, set the Cancel property of the ListViewDeleteEventArgs object to true. You can also work with the Keys and Values collections before the values are passed to the data source.
For more information about how to handle events, see Handling and Raising Events.
Applies to
See also
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