ListView.SelectedValue Property
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Gets the data-key value of the selected item in a ListView control.
public:
property System::Object ^ SelectedValue { System::Object ^ get(); };[System.ComponentModel.Browsable(false)]
public object SelectedValue { get; }[<System.ComponentModel.Browsable(false)>]
member this.SelectedValue : objPublic ReadOnly Property SelectedValue As ObjectProperty Value
The data-key value of the selected item in a ListView control.
- Attributes
Examples
The following example shows how to use the first key field as a parameter in a master/detail scenario. When an item is selected in the ListView control, the SelectedValue property is used as the PropertyName for the ControlParameter object. This parameter object is in turn used by the SqlDataSource control that the second ListView control is bound to.
<%@ 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>
The following example shows how to use the SelectedValue property to determine the value of the key field.
<%@ 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 DepartmentsListView_SelectedIndexChanged(object sender, EventArgs e)
{
MessageLabel.Text = "The key value is " +
DepartmentsListView.SelectedValue.ToString() + ".";
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>ListView SelectedValue Example</title>
<style type="text/css">
.header
{
border: 1px solid #008080;
background-color: #008080;
color: White;
}
.item td { border: 1px solid #008080; }
.selection td
{
border: 1px solid #008080;
background-color: #7FFF00;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<h3>ListView SelectedValue Example</h3>
<asp:ListView runat="server"
ID="DepartmentsListView"
DataSourceID="DepartmentDataSource"
DataKeyNames="DepartmentID"
OnSelectedIndexChanged="DepartmentsListView_SelectedIndexChanged">
<LayoutTemplate>
<b>Department List</b>
<br />
<table width="500px" runat="server" id="tblDepartments">
<tr class="header" runat="server">
<th runat="server"> </th>
<th runat="server">Department Name</th>
<th runat="server">Group Name</th>
</tr>
<tr runat="server" id="itemPlaceholder" />
</table>
</LayoutTemplate>
<ItemTemplate>
<tr class="item" runat="server">
<td>
<asp:LinkButton runat="server"
ID="SelectButton"
Text="Select"
CommandName="Select" />
</td>
<td>
<asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
</td>
<td>
<asp:Label runat="server" ID="GroupNameLabel" Text='<%#Eval("GroupName") %>' />
</td>
</tr>
</ItemTemplate>
<SelectedItemTemplate>
<tr class="selection" runat="server">
<td> </td>
<td>
<asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
</td>
<td>
<asp:Label runat="server" ID="GroupNameLabel" Text='<%#Eval("GroupName") %>' />
</td>
</tr>
</SelectedItemTemplate>
</asp:ListView>
<br/>
<asp:Label ID="MessageLabel"
ForeColor="Red"
runat="server"/>
<!-- 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="DepartmentDataSource" runat="server"
ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
SelectCommand="SELECT DepartmentID, Name, GroupName
FROM HumanResources.Department">
</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 DepartmentsListView_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
MessageLabel.Text = "The key value is " & _
DepartmentsListView.SelectedValue.ToString() & "."
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>ListView SelectedValue Example</title>
<style type="text/css">
.header
{
border: 1px solid #008080;
background-color: #008080;
color: White;
}
.item td { border: 1px solid #008080; }
.selection td
{
border: 1px solid #008080;
background-color: #7FFF00;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<h3>ListView SelectedValue Example</h3>
<asp:ListView runat="server"
ID="DepartmentsListView"
DataSourceID="DepartmentDataSource"
DataKeyNames="DepartmentID"
OnSelectedIndexChanged="DepartmentsListView_SelectedIndexChanged">
<LayoutTemplate>
<b>Department List</b>
<br />
<table width="500px" runat="server" id="tblDepartments">
<tr class="header" runat="server">
<th runat="server"> </th>
<th runat="server">Department Name</th>
<th runat="server">Group Name</th>
</tr>
<tr runat="server" id="itemPlaceholder" />
</table>
</LayoutTemplate>
<ItemTemplate>
<tr class="item" runat="server">
<td>
<asp:LinkButton runat="server"
ID="SelectButton"
Text="Select"
CommandName="Select" />
</td>
<td>
<asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
</td>
<td>
<asp:Label runat="server" ID="GroupNameLabel" Text='<%#Eval("GroupName") %>' />
</td>
</tr>
</ItemTemplate>
<SelectedItemTemplate>
<tr class="selection" runat="server">
<td> </td>
<td>
<asp:Label runat="server" ID="NameLabel" Text='<%#Eval("Name") %>' />
</td>
<td>
<asp:Label runat="server" ID="GroupNameLabel" Text='<%#Eval("GroupName") %>' />
</td>
</tr>
</SelectedItemTemplate>
</asp:ListView>
<br/>
<asp:Label ID="MessageLabel"
ForeColor="Red"
runat="server"/>
<!-- 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="DepartmentDataSource" runat="server"
ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
SelectCommand="SELECT DepartmentID, Name, GroupName
FROM HumanResources.Department">
</asp:SqlDataSource>
</form>
</body>
</html>
Remarks
The DataKeyNames property can be set to a comma-separated list of field names that represent the primary key of the data source. If it is set, the ListView control automatically creates a DataKey object for each item in the control by using the value or values of the specified field or fields. The DataKey objects are then added to the control's DataKeys collection.
Normally, the DataKeys property is used to get the DataKey object for a specific data item in the ListView control. However, if you want to get only the DataKey object of the currently selected item, you can use the SelectedDataKey property as a shortcut. You can also directly determine the data-key value of the first key field of the selected item by using the SelectedValue property.
If you are creating a ControlParameter object and want to access a key field other than the first field, use the SelectedDataKey property. For an example, see the SelectedDataKey property.
Applies to
See also
التعاون معنا على GitHub
يمكن العثور على مصدر هذا المحتوى على GitHub حيث يمكنك أيضاً إضافة مشاكل وطلبات سحب ومراجعتها. للحصول على معلومات إضافية، اطلع على دليل المساهم لدينا.
