ListView.SelectedValue Właściwość

Definicja

Pobiera wartość klucza danych wybranego elementu w ListView kontrolce.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 : obj
Public ReadOnly Property SelectedValue As Object

Wartość właściwości

Object

Wartość klucza danych wybranego elementu w ListView kontrolce.The data-key value of the selected item in a ListView control.

Atrybuty

Przykłady

Poniższy przykład pokazuje, jak używać pierwszego pola klucza jako parametru w scenariuszu wzorzec/szczegóły.The following example shows how to use the first key field as a parameter in a master/detail scenario. Gdy element jest zaznaczony w ListView kontrolce, SelectedValue Właściwość jest używana jako PropertyName dla ControlParameter obiektu.When an item is selected in the ListView control, the SelectedValue property is used as the PropertyName for the ControlParameter object. Ten obiekt parametru jest z kolei używany przez SqlDataSource kontrolkę, z którą ListView jest powiązany drugi formant.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>

Poniższy przykład pokazuje, jak użyć właściwości, SelectedValue Aby określić wartość pola klucza.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">&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>

Uwagi

DataKeyNamesWłaściwość można ustawić na rozdzieloną przecinkami listę nazw pól reprezentujących klucz podstawowy źródła danych.The DataKeyNames property can be set to a comma-separated list of field names that represent the primary key of the data source. Jeśli jest ustawiona, ListView formant automatycznie tworzy DataKey obiekt dla każdego elementu w kontrolce przy użyciu wartości lub wartości określonego pola lub pola.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. DataKeyObiekty są następnie dodawane do kolekcji kontrolki DataKeys .The DataKey objects are then added to the control's DataKeys collection.

Zwykle DataKeys Właściwość jest używana do pobierania DataKey obiektu dla określonego elementu danych w ListView formancie.Normally, the DataKeys property is used to get the DataKey object for a specific data item in the ListView control. Jeśli jednak chcesz uzyskać tylko DataKey obiekt aktualnie wybranego elementu, możesz użyć SelectedDataKey właściwości jako skrótu.However, if you want to get only the DataKey object of the currently selected item, you can use the SelectedDataKey property as a shortcut. Możesz również bezpośrednio określić wartość klucza danych pierwszego pola klucza wybranego elementu przy użyciu SelectedValue właściwości.You can also directly determine the data-key value of the first key field of the selected item by using the SelectedValue property.

Jeśli tworzysz ControlParameter obiekt i chcesz uzyskać dostęp do pola klucza innego niż pierwsze pole, użyj SelectedDataKey właściwości.If you are creating a ControlParameter object and want to access a key field other than the first field, use the SelectedDataKey property. Aby zapoznać się z przykładem, zobacz SelectedDataKey Właściwość.For an example, see the SelectedDataKey property.

Dotyczy

Zobacz też