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ListView.SelectedValue Vlastnost

  • Reference

Definice

Obor názvů:
System.Web.UI.WebControls
Sestavení:
System.Web.Extensions.dll

Získá hodnotu klíče dat vybrané položky v ovládacím ListView prvku.

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

Hodnota vlastnosti

Object

Hodnota klíče dat vybrané položky v ovládacím ListView prvku.

Atributy
BrowsableAttribute

Příklady

Následující příklad ukazuje, jak použít pole s prvním klíčem jako parametr ve scénáři hlavní/podrobný. Při výběru položky v ovládacím ListView prvku se SelectedValue vlastnost použije jako PropertyName objekt ControlParameter . Tento objekt parametru je následně používán ovládacím SqlDataSource prvek, ke kterému je druhý ListView ovládací prvek vázán.

<%@ 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>

Následující příklad ukazuje, jak použít SelectedValue vlastnost k určení hodnoty pole klíče.

<%@ 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>

Poznámky

Vlastnost DataKeyNames lze nastavit na seznam názvů polí oddělených čárkami, které představují primární klíč zdroje dat. Pokud je nastavena, ListView ovládací prvek automaticky vytvoří DataKey objekt pro každou položku v ovládacím prvku pomocí hodnoty nebo hodnot zadaného pole nebo polí. Objekty DataKey se pak přidají do kolekce ovládacího prvku DataKeys .

Vlastnost se DataKeys obvykle používá k získání objektu DataKey pro konkrétní položku dat v ovládacím ListView prvku. Pokud však chcete získat pouze DataKey objekt aktuálně vybrané položky, můžete použít SelectedDataKey vlastnost jako zástupce. Pomocí vlastnosti můžete také přímo určit hodnotu datového klíče pole prvního klíče vybrané položky SelectedValue .

Pokud vytváříte ControlParameter objekt a chcete získat přístup k jinému poli klíče než k prvnímu poli, použijte SelectedDataKey vlastnost . Příklad: Podívejte se na SelectedDataKey vlastnost .

Platí pro

Viz také