ListViewUpdateEventArgs.Keys Propriedade

Definição

Obtém um dicionário de pares nome/valor de campo que representam uma ou mais chaves do item a atualizar.Gets a dictionary of field name/value pairs that represent the key or keys of the item to update.

public:
 property System::Collections::Specialized::IOrderedDictionary ^ Keys { System::Collections::Specialized::IOrderedDictionary ^ get(); };
public System.Collections.Specialized.IOrderedDictionary Keys { get; }
member this.Keys : System.Collections.Specialized.IOrderedDictionary
Public ReadOnly Property Keys As IOrderedDictionary

Valor da propriedade

IOrderedDictionary

Os pares de nome/valor do campo que representam a chave ou chaves do item a ser atualizado.The field name/value pairs that represent the key or keys of the item to update.

Exemplos

O exemplo a seguir mostra como usar a Keys propriedade para acessar o valor do campo de chave para o registro que está sendo atualizado.The following example shows how to use the Keys property to access the value of the key field for the record being updated.

Importante

Este exemplo tem uma caixa de texto que aceita a entrada do usuário, que é uma possível ameaça à segurança.This example has a text box that accepts user input, which is a potential security threat. Por padrão, as páginas da Web do ASP.NET validam que a entrada do usuário não inclui elementos de script ou HTML.By default, ASP.NET Web pages validate that user input does not include script or HTML elements. Para obter mais informações, consulte Visão geral de explorações de script.For more information, see Script Exploits Overview.

<%@ 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">
    
  void Page_Load()
  {
    Message.Text = String.Empty;
  }
    
  //<Snippet2>
  void UnitMeasureListView_ItemUpdating(Object sender, ListViewUpdateEventArgs e)
  {
    // Use the Keys property to retrieve the key field value
    String keyValue = e.Keys[0].ToString().Trim();

    // Cancel the update operation if the user attempts to 
    // edit a protected record. In this example, unit measure
    // codes with 3 letters are protected.
    if (keyValue.Length == 3)
    {
      Message.Text = "You cannot update this record. " +
        " Unit Measure Code " + keyValue + " is protected.";
        e.Cancel = true;
    }    
  }
  //</Snippet2>
  
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>ListViewUpdateEventArgs Keys Example</title>
  </head>
  <body>
    <form id="form1" runat="server">
        
      <h3>ListViewUpdateEventArgs Keys Example</h3>
            
      <asp:Label ID="Message"
        ForeColor="Red"          
        runat="server"/>
      <br/>

      <asp:ListView ID="UnitMeasureListView" 
        DataSourceID="UnitMeasureDataSource" 
        DataKeyNames="UnitMeasureCode"
        OnItemUpdating="UnitMeasureListView_ItemUpdating"  
        runat="server">
        <LayoutTemplate>
          <table width="400px" border="1" id="tblUnit">
            <tr runat="server">
              <th runat="server">&nbsp;</th>
              <th runat="server">Unit Measure Code</th>
              <th runat="server">Name</th>
            </tr>
            <tr id="itemPlaceholder" runat="server"></tr>
          </table>
        </LayoutTemplate>
        <ItemTemplate>
          <tr runat="server">
            <td>
              <asp:Button ID="EditButton" runat="server" CommandName="Edit" Text="Edit" />
            </td>
            <td>
              <asp:Label ID="CodeLabel" runat="server" Text='<%#Eval("UnitMeasureCode") %>' />
            </td>
            <td>
              <asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("Name") %>' />
            </td>
          </tr>
        </ItemTemplate>
        <AlternatingItemTemplate>
          <tr style="background-color:#B0C4DE" runat="server">
            <td>
              <asp:Button ID="EditButton" runat="server" CommandName="Edit" Text="Edit" />
            </td>
            <td>
              <asp:Label ID="CodeLabel" runat="server" Text='<%#Eval("UnitMeasureCode") %>' />
            </td>
            <td>
              <asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("Name") %>' />
            </td>
          </tr>
        </AlternatingItemTemplate>
        <EditItemTemplate>
          <tr style="background-color:#4682B4">
            <td>
              <asp:Button ID="UpdateButton" runat="server" CommandName="Update" Text="Update" />
              <asp:Button ID="CancelButton" runat="server" CommandName="Cancel" Text="Cancel" />
            </td>
            <td>
              <asp:Label ID="CodeLabel" runat="server" Text='<%#Eval("UnitMeasureCode") %>' />
            </td>
            <td>
              <asp:TextBox ID="NameTextBox" runat="server" Text='<%#Bind("Name") %>' MaxLength="50" /><br />
            </td>
          </tr>
        </EditItemTemplate>
      </asp:ListView>

      <!-- 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="UnitMeasureDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
        SelectCommand="SELECT [UnitMeasureCode], [Name] FROM Production.UnitMeasure"
        UpdateCommand="UPDATE Production.UnitMeasure
                       SET [Name] = @Name
                       WHERE [UnitMeasureCode] = @UnitMeasureCode">
      </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">
   
  Sub Page_Load() 
      Message.Text = String.Empty
  End Sub 'Page_Load

  Sub UnitMeasureListView_ItemUpdating(ByVal sender As Object, ByVal e As ListViewUpdateEventArgs)
    ' Use the Keys property to retrieve the key field value
    Dim keyValue As String = e.Keys(0).ToString().Trim()
    
    ' Cancel the update operation if the user attempts to 
    ' edit a protected record. In this example, unit measure
    ' codes with 3 letters are protected.
    If keyValue.Length = 3 Then
      Message.Text = "You cannot update this record. " & _
        " Unit Measure Code " & keyValue & " is protected."
      e.Cancel = True
    End If

  End Sub 'UnitMeasureListView_ItemUpdating

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head id="Head1" runat="server">
    <title>ListViewUpdateEventArgs Keys Example</title>
  </head>
  <body>
    <form id="form1" runat="server">
        
      <h3>ListViewUpdateEventArgs Keys Example</h3>
            
      <asp:Label ID="Message"
        ForeColor="Red"          
        runat="server"/>
      <br/>

      <asp:ListView ID="UnitMeasureListView" 
        DataSourceID="UnitMeasureDataSource" 
        DataKeyNames="UnitMeasureCode"
        OnItemUpdating="UnitMeasureListView_ItemUpdating"  
        runat="server">
        <LayoutTemplate>
          <table width="400px" border="1" id="tblUnit">
            <tr runat="server">
              <th runat="server">&nbsp;</th>
              <th runat="server">Unit Measure Code</th>
              <th runat="server">Name</th>
            </tr>
            <tr id="itemPlaceholder" runat="server"></tr>
          </table>
        </LayoutTemplate>
        <ItemTemplate>
          <tr runat="server">
            <td>
              <asp:Button ID="EditButton" runat="server" CommandName="Edit" Text="Edit" />
            </td>
            <td>
              <asp:Label ID="CodeLabel" runat="server" Text='<%#Eval("UnitMeasureCode") %>' />
            </td>
            <td>
              <asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("Name") %>' />
            </td>
          </tr>
        </ItemTemplate>
        <AlternatingItemTemplate>
          <tr style="background-color:#B0C4DE" runat="server">
            <td>
              <asp:Button ID="EditButton" runat="server" CommandName="Edit" Text="Edit" />
            </td>
            <td>
              <asp:Label ID="CodeLabel" runat="server" Text='<%#Eval("UnitMeasureCode") %>' />
            </td>
            <td>
              <asp:Label ID="FirstNameLabel" runat="server" Text='<%#Eval("Name") %>' />
            </td>
          </tr>
        </AlternatingItemTemplate>
        <EditItemTemplate>
          <tr style="background-color:#4682B4">
            <td>
              <asp:Button ID="UpdateButton" runat="server" CommandName="Update" Text="Update" />
              <asp:Button ID="CancelButton" runat="server" CommandName="Cancel" Text="Cancel" />
            </td>
            <td>
              <asp:Label ID="CodeLabel" runat="server" Text='<%#Eval("UnitMeasureCode") %>' />
            </td>
            <td>
              <asp:TextBox ID="NameTextBox" runat="server" Text='<%#Bind("Name") %>' MaxLength="50" /><br />
            </td>
          </tr>
        </EditItemTemplate>
      </asp:ListView>

      <!-- 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="UnitMeasureDataSource" runat="server" 
        ConnectionString="<%$ ConnectionStrings:AdventureWorks_DataConnectionString %>"
        SelectCommand="SELECT [UnitMeasureCode], [Name] FROM Production.UnitMeasure"
        UpdateCommand="UPDATE Production.UnitMeasure
                       SET [Name] = @Name
                       WHERE [UnitMeasureCode] = @UnitMeasureCode">
      </asp:SqlDataSource>
      
    </form>
  </body>
</html>

Comentários

Quando a DataKeyNames propriedade de um ListView controle for definida, use a Keys Propriedade (Dictionary) para acessar o valor da chave primária no item a ser atualizado.When the DataKeyNames property of a ListView control is set, use the Keys property (dictionary) to access the value of the primary key in the item to update.

Observação

Para acessar os valores dos campos não chave, use as NewValues OldValues Propriedades ou.To access the values of the non-key fields, use the NewValues or OldValues properties. A NewValues propriedade contém os valores atualizados e a OldValues propriedade contém os valores originais.The NewValues property contains the updated values, and the OldValues property contains the original values.

O Keys dicionário é preenchido automaticamente com os pares de nome/valor do campo ou campos especificados na DataKeyNames propriedade.The Keys dictionary is automatically populated with the name/value pairs of the field or fields specified in the DataKeyNames property. Se vários campos formarem a chave primária, uma entrada separada será adicionada ao Keys dicionário para cada campo de chave.If multiple fields form the primary key, a separate entry is added to the Keys dictionary for every key field.

Para determinar o nome de um campo de chave, use a DictionaryEntry.Key propriedade de um DictionaryEntry objeto contido no Keys dicionário.To determine the name of a key field, use the DictionaryEntry.Key property of a DictionaryEntry object that is contained in the Keys dictionary. Para determinar o valor de um campo de chave, use a DictionaryEntry.Value propriedade.To determine the value of a key field, use the DictionaryEntry.Value property.

Aplica-se a

Confira também