Επεξεργασία

Κοινή χρήση μέσω

AddingNewEventHandler Delegate

  • Reference

Definition

Namespace:
System.ComponentModel
Assembly:
System.ComponentModel.TypeConverter.dll
Assembly:
System.dll
Assembly:
netstandard.dll

Represents the method that will handle the AddingNew event.

public delegate void AddingNewEventHandler(System::Object ^ sender, AddingNewEventArgs ^ e);
public delegate void AddingNewEventHandler(object sender, AddingNewEventArgs e);
public delegate void AddingNewEventHandler(object? sender, AddingNewEventArgs e);
type AddingNewEventHandler = delegate of obj * AddingNewEventArgs -> unit
Public Delegate Sub AddingNewEventHandler(sender As Object, e As AddingNewEventArgs)

Parameters

sender
Object

The source of the event, typically a data container or data-bound collection.

e
AddingNewEventArgs

A AddingNewEventArgs that contains the event data.

Examples

The following code example demonstrates how to use the AddingNewEventHandler delegate to handle the BindingSource.AddingNew event. This code example is part of a larger example provided in How to: Customize Item Addition with the Windows Forms BindingSource.

// This event handler provides custom item-creation behavior.
void OnCustomersBindingSourceAddingNew(Object^ sender, 
    AddingNewEventArgs^ e)
{
    e->NewObject = DemoCustomer::CreateNewCustomer();
}

// This event handler provides custom item-creation behavior.
void customersBindingSource_AddingNew(
    object sender, 
    AddingNewEventArgs e)
{
    e.NewObject = DemoCustomer.CreateNewCustomer();
}

' This event handler provides custom item-creation behavior.
 Private Sub customersBindingSource_AddingNew( _
 ByVal sender As Object, _
 ByVal e As AddingNewEventArgs) _
 Handles customersBindingSource.AddingNew

     e.NewObject = DemoCustomer.CreateNewCustomer()

 End Sub

Remarks

The BindingSource.AddingNew event occurs prior to adding a new item to a collection, typically in data-binding scenarios. The handler of this event can supply the new item to be added, overriding the standard action of the collection class. This is accomplished by setting the NewObject property of the AddingNewEventArgs parameter e to this new item. Typically this item must be of a type expected by the recipient collection, or the collection will throw an exception of type InvalidCastException.

This event is commonly used in data-binding scenarios, within classes such as System.Windows.Forms.BindingSource and System.ComponentModel.BindingList<T>.

When you create an AddingNewEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Handling and Raising Events.

Extension Methods

GetMethodInfo(Delegate)

Gets an object that represents the method represented by the specified delegate.

Applies to

See also