ListView.SelectedValue 属性

参考

定义

命名空间:: System.Web.UI.WebControls

程序集:: System.Web.Extensions.dll

重要

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获取 ListView 控件中的选定项的数据键值。

public:
 property System::Object ^ SelectedValue { System::Object ^ get(); };

[System.ComponentModel.Browsable(false)]
public object SelectedValue { get; }

[<System.ComponentModel.Browsable(false)>]
member this.SelectedValue : obj

Public ReadOnly Property SelectedValue As Object

属性值

Object

ListView 控件中的选定项的数据键值。

属性: BrowsableAttribute

示例

以下示例演示如何在 master/detail 方案中使用第一个键字段作为参数。在控件中选择 ListView 某个项时，该 SelectedValue 属性将用作 PropertyName 对象 ControlParameter 的属性。此参数对象由第二ListView个控件绑定到的控件使用SqlDataSource。

<%@ 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>

以下示例演示如何使用 SelectedValue 属性来确定键字段的值。

<%@ 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">&nbsp;</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>&nbsp;</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">&nbsp;</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>&nbsp;</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>

注解

该 DataKeyNames 属性可以设置为一个逗号分隔的字段名称列表，该列表表示数据源的主键。如果设置了该控件，控件 ListView 将使用指定字段或字段的值自动为控件中的每个项创建一个 DataKey 对象。 DataKey然后将对象添加到控件的DataKeys集合中。

通常，该 DataKeys 属性用于获取 DataKey 控件中 ListView 特定数据项的对象。但是，如果只想获取 DataKey 当前所选项的对象，则可以将 SelectedDataKey 属性用作快捷方式。还可以使用 SelectedValue 属性直接确定所选项的第一个键字段的数据键值。

如果要创建 ControlParameter 对象并想要访问第一个字段以外的键字段，请使用该 SelectedDataKey 属性。有关示例，请参阅该 SelectedDataKey 属性。

适用于

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ListView.SelectedValue 属性

定义

属性值

示例

注解

适用于

另请参阅

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