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BindingsCollection.CollectionChanging Event

Occurs when the collection is about to change.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public event CollectionChangeEventHandler CollectionChanging

For more information about handling events, see Handling and Raising Events.

The following code example demonstrates the use of this member. In the example, an event handler reports on the occurrence of the CollectionChanging event. This report helps you to learn when the event occurs and can assist you in debugging. To report on multiple events or on events that occur frequently, consider replacing MessageBox.Show with Console.WriteLine or appending the message to a multiline TextBox.

To run the example code, paste it into a project that contains an instance of type BindingsCollection named BindingsCollection1. Then ensure that the event handler is associated with the CollectionChanging event.

private void BindingsCollection1_CollectionChanging(Object sender, CollectionChangeEventArgs e) {

System.Text.StringBuilder messageBoxCS = new System.Text.StringBuilder();
messageBoxCS.AppendFormat("{0} = {1}", "Action", e.Action );
messageBoxCS.AppendLine();
messageBoxCS.AppendFormat("{0} = {1}", "Element", e.Element );
messageBoxCS.AppendLine();
MessageBox.Show(messageBoxCS.ToString(), "CollectionChanging Event" );
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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