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DetailsViewUpdateEventArgs.Keys Propriedade

Definição

Obtém um dicionário que contém os pares nome-valor de campo de chave para o registro a ser atualizado.

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

Um IOrderedDictionary que contém um dicionário de pares de nome/valor de campo de chave para o registro a ser atualizado.

Exemplos

O exemplo de código a seguir demonstra como usar a Keys propriedade para acessar o valor do campo de chave para o registro que está sendo atualizado.


<%@ 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 CustomerDetailsView_ItemUpdating(Object sender, 
      DetailsViewUpdateEventArgs e)
    {

        // Validate the field values entered by the user. This
        // example determines whether the user left any fields
        // empty. Use the NewValues property to access the new 
        // values entered by the user.
        ArrayList emptyFieldList = 
          ValidateFields((IOrderedDictionary)e.NewValues);

        if (emptyFieldList.Count > 0)
        {

            // The user left some fields empty. 
            // Display an error message.

            // Use the Keys property to retrieve the key field value.
            String keyValue = e.Keys["CustomerID"].ToString();

            MessageLabel.Text = 
              "You must enter a value for all fields of record " +
              keyValue + ".<br/>The following fields are missing:<br/><br/>";

            // Display the missing fields.
            foreach (String value in emptyFieldList)
            {
                // Use the OldValues property access the original
                // value of a field.
                MessageLabel.Text += value + " - Original Value = " +
                  e.OldValues[value].ToString() + "<br />";
            }

            // Cancel the update operation.
            e.Cancel = true;

        }
        else
        {
            // The field values passed validation. Clear the
            // error message label.
            MessageLabel.Text = "";
        }

    }

    ArrayList ValidateFields(IOrderedDictionary list)
    {

        // Create an ArrayList object to store the
        // names of any empty fields.
        ArrayList emptyFieldList = new ArrayList();

        // Iterate though the field values entered by
        // the user and check for an empty field. Empty
        // fields contain a null value.
        foreach (DictionaryEntry entry in list)
        {
            if (entry.Value == null)
            {
                // Add the field name to the ArrayList object.
                emptyFieldList.Add(entry.Key.ToString());
            }
        }

        return emptyFieldList;
    }

    void CustomerDetailsView_ModeChanging(Object sender, 
      DetailsViewModeEventArgs e)
    {
        if (e.CancelingEdit)
        {
            // The user canceled the update operation.
            // Clear the error message label.
            MessageLabel.Text = "";
        }
    }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >

  <head runat="server">
    <title>DetailsViewUpdateEventArgs Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>DetailsViewUpdateEventArgs Example</h3>
                       
        <asp:detailsview id="CustomerDetailsView"
          datasourceid="DetailsViewSource"
          autogeneraterows="true"
          autogenerateeditbutton="true"  
          allowpaging="true"
          datakeynames="CustomerID" 
          onitemupdating="CustomerDetailsView_ItemUpdating"
          onmodechanging="CustomerDetailsView_ModeChanging" 
          runat="server">
            
          <pagersettings position="Bottom"/> 
                    
        </asp:detailsview>
        
        <br/>
        
        <asp:label id="MessageLabel"
          forecolor="Red"
          runat="server"/>
            
        <!-- This example uses Microsoft SQL Server and connects  -->
        <!-- to the Northwind sample database. Use an ASP.NET     -->
        <!-- expression to retrieve the connection string value   -->
        <!-- from the web.config file.                            -->
        <asp:sqldatasource id="DetailsViewSource"
          selectcommand="Select [CustomerID], [CompanyName], [Address], 
            [City], [PostalCode], [Country] From [Customers]"
          updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country 
          Where [CustomerID]=@CustomerID"
          connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
          runat="server"/>
            
      </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 CustomerDetailsView_ItemUpdating(ByVal sender As Object, _
    ByVal e As DetailsViewUpdateEventArgs)

    ' Validate the field values entered by the user. This
    ' example determines whether the user left any fields
    ' empty. Use the NewValues property to access the new 
    ' values entered by the user.
    Dim emptyFieldList As ArrayList = _
      ValidateFields(CType(e.NewValues, IOrderedDictionary))

    If emptyFieldList.Count > 0 Then

      ' The user left some fields empty. Display an error message.
      
      ' Use the Keys property to retrieve the key field value.
      Dim keyValue As String = e.Keys("CustomerID").ToString()

      MessageLabel.Text = _
        "You must enter a value for all fields of record " & _
        keyValue & ".<br/>The following fields are missing:<br/><br/>"

      ' Display the missing fields.
      Dim value As String
      For Each value In emptyFieldList
      
        ' Use the OldValues property access the original value
        ' of a field.
        MessageLabel.Text &= value & " - Original Value = " & _
          e.OldValues(value).ToString() & "<br />"
        
      Next

      ' Cancel the update operation.
      e.Cancel = True

    Else
    
      ' The field values passed validation. Clear the
      ' error message label.
      MessageLabel.Text = ""
      
    End If

  End Sub

    Function ValidateFields(ByVal list As IOrderedDictionary) _
      As ArrayList
    
        ' Create an ArrayList object to store the
        ' names of any empty fields.
        Dim emptyFieldList As New ArrayList()

        ' Iterate though the field values entered by
        ' the user and check for an empty field. Empty
        ' fields contain a null value.
        Dim entry As DictionaryEntry
    
        For Each entry In list
    
            If entry.Value Is Nothing Then
      
                ' Add the field name to the ArrayList object.
                emptyFieldList.Add(entry.Key.ToString())
        
            End If
        Next

        Return emptyFieldList
  
    End Function

  Sub CustomerDetailsView_ModeChanging(ByVal sender As Object, ByVal e As DetailsViewModeEventArgs)
  
    If e.CancelingEdit Then
      
      ' The user canceled the update operation.
      ' Clear the error message label.
      MessageLabel.Text = ""
    
    End If
    
  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >

  <head runat="server">
    <title>DetailsViewUpdateEventArgs Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>DetailsViewUpdateEventArgs Example</h3>
                       
        <asp:detailsview id="CustomerDetailsView"
          datasourceid="DetailsViewSource"
          autogeneraterows="true"
          autogenerateeditbutton="true"  
          allowpaging="true"
          datakeynames="CustomerID" 
          onitemupdating="CustomerDetailsView_ItemUpdating"
          onmodechanging="CustomerDetailsView_ModeChanging" 
          runat="server">
            
          <pagersettings position="Bottom"/> 
                    
        </asp:detailsview>
        
        <br/>
        
        <asp:label id="MessageLabel"
          forecolor="Red"
          runat="server"/>
            
        <!-- This example uses Microsoft SQL Server and connects  -->
        <!-- to the Northwind sample database. Use an ASP.NET     -->
        <!-- expression to retrieve the connection string value   -->
        <!-- from the web.config file.                            -->
        <asp:sqldatasource id="DetailsViewSource"
          selectcommand="Select [CustomerID], [CompanyName], [Address], 
          [City], [PostalCode], [Country] From [Customers]"
          updatecommand="Update [Customers] Set 
          [CompanyName]=@CompanyName, [Address]=@Address, 
          [City]=@City, [PostalCode]=@PostalCode, 
          [Country]=@Country 
          Where [CustomerID]=@CustomerID"
          connectionstring=
          "<%$ ConnectionStrings:NorthWindConnectionString%>" 
          runat="server"/>
            
      </form>
  </body>
</html>

Comentários

Use a Keys propriedade para acessar os valores dos campos de chave para que o registro seja atualizado. Por exemplo, você pode usar esses valores para manter um log de registros atualizados.

Observação

Essa propriedade contém apenas os campos de chave. Para acessar os campos não chave atualizados e originais, use as propriedades e OldValues as NewValues propriedades, respectivamente.

A propriedade de Keys retorna um objeto que implementa a interface de IOrderedDictionary. O objeto contém DictionaryEntry objetos que representam os campos do registro a ser atualizado.

Observação

Como atalho, você também pode usar o indexador do IOrderedDictionary objeto para acessar os valores de campo diretamente.

Aplica-se a

Confira também