GridViewUpdatedEventArgs.OldValues Property
Definition
Important
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Gets a dictionary that contains the original field name/value pairs for the updated record.
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.IOrderedDictionaryPublic ReadOnly Property OldValues As IOrderedDictionaryProperty Value
A dictionary of the original field name/value pairs for the updated record.
Examples
The following example shows how to access the original values of the non-key fields for the updated record.
<%@ 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>
Remarks
Use the OldValues property to access the original field values for the updated record. For example, you can use these values to keep a log of updated records.
The OldValues property returns an object that implements the System.Collections.Specialized.IOrderedDictionary interface. The object contains System.Collections.DictionaryEntry objects that represent the fields of the updated record with their original values.
Note
As a shortcut, you can also use the indexer of the IOrderedDictionary object to access the field values directly.
Applies to
See also
GitHub पर हमारे साथ सहयोग करें
इस सामग्री का स्रोत GitHub पर पाया जा सकता है, जहाँ आप समस्याएँ बना और समीक्षा भी कर सकते हैं और अनुरोध खींच सकते हैं. अधिक जानकारी के लिए, हमारे योगदानकर्ता गाइड देखें.
