GridViewUpdatedEventArgs.OldValues Свойство

Ссылка

Определение

Пространство имен:: System.Web.UI.WebControls

Сборка:: System.Web.dll

Важно!

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Возвращает словарь, содержащий пары "имя-значение" исходного поля для обновленной записи.

public:
 property System::Collections::Specialized::IOrderedDictionary ^ OldValues { System::Collections::Specialized::IOrderedDictionary ^ get(); };

public System.Collections.Specialized.IOrderedDictionary OldValues { get; }

member this.OldValues : System.Collections.Specialized.IOrderedDictionary

Public ReadOnly Property OldValues As IOrderedDictionary

Значение свойства

IOrderedDictionary

Словарь пар "имя-значение" исходного поля обновленной записи.

Примеры

В следующем примере показано, как получить доступ к исходным значениям неключевых полей для обновленной записи.


<%@ 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 CustomersGridView_RowUpdated(Object sender, GridViewUpdatedEventArgs e)
  {
    // Use the Exception property to determine whether an exception
    // occurred during the update operation.
    if (e.Exception == null)
    {
      // Sometimes an error might occur that does not raise an 
      // exception, but prevents the update operation from 
      // completing. Use the AffectedRows property to determine 
      // whether the record was actually updated. 
      if (e.AffectedRows == 1)
      {
        // Use the Keys property to get the value of the key field.
        String keyFieldValue = e.Keys["CustomerID"].ToString();

        // Display a confirmation message.
        Message.Text = "Record " + keyFieldValue +
          " updated successfully. ";

        // Display the new and original values.
        DisplayValues((OrderedDictionary)e.NewValues, (OrderedDictionary)e.OldValues);
      }
      else
      {
        // Display an error message.
        Message.Text = "An error occurred during the update operation.";

        // When an error occurs, keep the GridView
        // control in edit mode.
        e.KeepInEditMode = true;
      }
    }
    else
    {
      // Insert the code to handle the exception.
      Message.Text = e.Exception.Message;

      // Use the ExceptionHandled property to indicate that the 
      // exception is already handled.
      e.ExceptionHandled = true;

      e.KeepInEditMode = true;
    }
  }

  void DisplayValues(OrderedDictionary newValues, OrderedDictionary oldValues)
  {

    Message.Text += "<br/></br>";

    // Iterate through the new and old values. Display the
    // values on the page.
    for (int i = 0; i < oldValues.Count; i++)
    {
      Message.Text += "Old Value=" + oldValues[i].ToString() +
        ", New Value=" + newValues[i].ToString() + "<br/>";
    }

    Message.Text += "</br>";

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewUpdatedEventArgs Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewUpdatedEventArgs Example</h3>
            
      <!-- The GridView control automatically sets the columns     -->
      <!-- specified in the datakeynames property as read-only.    -->
      <!-- No input controls are rendered for these columns in     -->
      <!-- edit mode.                                              -->
      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="true"
        autogenerateeditbutton="true"
        allowpaging="true" 
        datakeynames="CustomerID"
        onrowupdated="CustomersGridView_RowUpdated" 
        runat="server">
      </asp:gridview>
      
      <br/>
      
      <asp:label id="Message"
        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="CustomersSqlDataSource"  
        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">
      </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 CustomersGridView_RowUpdated(sender As Object, e As GridViewUpdatedEventArgs)
  
    ' Use the Exception property to determine whether an exception
    ' occurred during the update operation.
    If e.Exception Is Nothing Then
    
      ' Sometimes an error might occur that does not raise an 
      ' exception, but prevents the update operation from 
      ' completing. Use the AffectedRows property to determine 
      ' whether the record was actually updated. 
      If e.AffectedRows = 1 Then
      
        ' Use the Keys property to get the value of the key field.
        Dim keyFieldValue As String = e.Keys("CustomerID").ToString()

        ' Display a confirmation message.
        Message.Text = "Record " & keyFieldValue & _
          " updated successfully. "

        ' Display the new and original values.
        DisplayValues(CType(e.NewValues, OrderedDictionary), CType(e.OldValues, OrderedDictionary))

      Else
      
        ' Display an error message.
        Message.Text = "An error occurred during the update operation."

        ' When an error occurs, keep the GridView
        ' control in edit mode.
        e.KeepInEditMode = True
        
      End If
    
    Else
    
      ' Insert the code to handle the exception.
      Message.Text = e.Exception.Message

      ' Use the ExceptionHandled property to indicate that the 
      ' exception is already handled.
      e.ExceptionHandled = True

      e.KeepInEditMode = True
    
    End If
  
  End Sub

  Sub DisplayValues(ByVal newValues As OrderedDictionary, ByVal oldValues As OrderedDictionary)

    Message.Text &= "<br/></br>"

    ' Iterate through the new and old values. Display the
    ' values on the page.
    Dim i As Integer
    For i = 0 To oldValues.Count - 1
    
      Message.Text &= "Old Value=" & oldValues(i).ToString() & _
        ", New Value=" & newValues(i).ToString() & "<br/>"
    Next

    Message.Text &= "</br>"

  End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewUpdatedEventArgs Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewUpdatedEventArgs Example</h3>
            
      <!-- The GridView control automatically sets the columns     -->
      <!-- specified in the datakeynames property as read-only.    -->
      <!-- No input controls are rendered for these columns in     -->
      <!-- edit mode.                                              -->
      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="true"
        autogenerateeditbutton="true"
        allowpaging="true" 
        datakeynames="CustomerID"
        onrowupdated="CustomersGridView_RowUpdated" 
        runat="server">
      </asp:gridview>
      
      <br/>
      
      <asp:label id="Message"
        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="CustomersSqlDataSource"  
        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">
      </asp:sqldatasource>
            
    </form>
  </body>
</html>

Используйте свойство для OldValues доступа к исходным значениям полей для обновленной записи. Например, эти значения можно использовать для ведения журнала обновленных записей.

Свойство OldValues возвращает объект, который реализует интерфейс System.Collections.Specialized.IOrderedDictionary. Объект содержит System.Collections.DictionaryEntry объекты, представляющие поля обновленной записи с исходными значениями.

Примечание

В качестве ярлыка можно также использовать индексатор объекта для IOrderedDictionary прямого доступа к значениям полей.

Применяется к

Поделиться через

GridViewUpdatedEventArgs.OldValues Свойство

Определение

Значение свойства

Примеры

Комментарии

Применяется к

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