LinqDataSource.Inserting Event
Definition
Important
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Occurs before an insert operation.
public:
event EventHandler<System::Web::UI::WebControls::LinqDataSourceInsertEventArgs ^> ^ Inserting;public event EventHandler<System.Web.UI.WebControls.LinqDataSourceInsertEventArgs> Inserting;member this.Inserting : EventHandler<System.Web.UI.WebControls.LinqDataSourceInsertEventArgs> Public Custom Event Inserting As EventHandler(Of LinqDataSourceInsertEventArgs) Event Type
Examples
The following example shows an event handler for the Inserting event that modifies data before the insert operation. The object from the NewObject property is cast to a type named Product. The DateModified property of the Product object is set to the current date and time.
protected void LinqDataSource_Inserting(object sender, LinqDataSourceInsertEventArgs e)
{
Product product = (Product)e.NewObject;
product.DateModified = DateTime.Now;
}
Protected Sub LinqDataSource_Inserting(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.LinqDataSourceInsertEventArgs)
Dim product As Product
product = CType(e.NewObject, Product)
product.DateModified = DateTime.Now
End Sub
The following example shows an event handler for the Inserting event that retrieves validation exceptions.
Protected Sub LinqDataSource_Inserting(ByVal sender As Object, _
ByVal e As LinqDataSourceInsertEventArgs)
If (e.Exception IsNot Nothing) Then
For Each innerException As KeyValuePair(Of String, Exception) _
In e.Exception.InnerExceptions
Label1.Text &= innerException.Key & ": " & _
innerException.Value.Message & "<br />"
Next
e.ExceptionHandled = True
End If
End Sub
protected void LinqDataSource_Inserting(object sender,
LinqDataSourceInsertEventArgs e)
{
if (e.Exception != null)
{
foreach (KeyValuePair<string, Exception> innerException in
e.Exception.InnerExceptions)
{
Label1.Text += innerException.Key + ": " +
innerException.Value.Message + "<br />";
}
e.ExceptionHandled = true;
}
}
The previous example retrieves validation exceptions. An exception might be thrown if a value does not match the type of the property. It might also be thrown from a customized check such as the one in the following example. The OnAgeChanging method checks that the number for the Age property is not negative.
partial void OnAgeChanging(int? value)
{
if (value < 0)
{
throw new Exception("Age cannot be a negative number.");
}
}
Private Sub OnAgeChanging(ByVal value As System.Nullable(Of Integer))
If (value < 0) Then
Throw New Exception("Age cannot be a negative number.")
End If
End Sub
Remarks
Handle the Inserting event to validate the object to be inserted, to examine data validation errors from the data class, to change a value before the insert operation, or to cancel the insert operation. The LinqDataSourceInsertEventArgs object passed to event handlers for this event contains the new object to insert in the data source.
If a validation error occurs during the insert operation, the LinqDataSourceInsertEventArgs object contains the validation exceptions that are thrown by the data class. A validation error occurs if a value to be inserted does not match the type of the property in the data class, or if it does not pass a custom validation check. In an event handler for the Inserting event, you can retrieve the validation exceptions and take appropriate action.
If an exception is thrown in an event handler for the Inserting event, you must handle the exception in that event handler. The exception will not be passed to an event handler for the Inserted event (through the Exception property of the LinqDataSourceStatusEventArgs object). The Exception property contains only the exceptions that are thrown after the Inserting event.
