ListView.SelectedValue Egenskap

Definition

Namnområde:: System.Web.UI.WebControls

Sammansättning:: System.Web.Extensions.dll

Viktigt

En del information gäller för förhandsversionen av en produkt och kan komma att ändras avsevärt innan produkten blir allmänt tillgänglig. Microsoft lämnar inga garantier, uttryckliga eller underförstådda, avseende informationen som visas här.

Hämtar datanyckelvärdet för det markerade objektet i en ListView kontroll.

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

Egenskapsvärde

Object

Datanyckelvärdet för det markerade objektet i en ListView kontroll.

Attribut: BrowsableAttribute

Exempel

I följande exempel visas hur du använder det första nyckelfältet som en parameter i ett huvud-/detaljscenario. När ett objekt markeras i ListView kontrollen SelectedValue används egenskapen som PropertyName för ControlParameter objektet. Det här parameterobjektet används i sin tur av den SqlDataSource kontroll som den andra ListView kontrollen är bunden till.

<%@ 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>

I följande exempel visas hur du använder SelectedValue egenskapen för att fastställa värdet för nyckelfältet.

<%@ 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>

Kommentarer

Egenskapen DataKeyNames kan anges till en kommaavgränsad lista med fältnamn som representerar datakällans primära nyckel. Om den anges ListView skapar kontrollen automatiskt ett DataKey objekt för varje objekt i kontrollen med hjälp av värdet eller värdena för det angivna fältet eller fälten. Objekten DataKey läggs sedan till i kontrollens DataKeys samling.

Normalt används egenskapen DataKeys för att hämta DataKey objektet för ett specifikt dataobjekt i ListView kontrollen. Men om du bara DataKey vill hämta objektet för det markerade objektet kan du använda SelectedDataKey egenskapen som en genväg. Du kan också direkt fastställa datanyckelvärdet för det första nyckelfältet i det markerade objektet med hjälp SelectedValue av egenskapen .

Om du skapar ett ControlParameter objekt och vill komma åt ett annat nyckelfält än det första fältet använder du SelectedDataKey egenskapen . Ett exempel finns i egenskapen SelectedDataKey .

Gäller för

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