RadObservableCollection and ObservableItemCollection
This article will give you information about the RadObservableCollection.
Overview
Simply put, a RadObservableCollection represents an ObservableCollection that has the ability to suspend change notification events. Here is a typical use-case:
Example 1: Using RadObservableCollection
clubs.SuspendNotifications();
foreach (var item in newItems)
{
clubs.Add(item);
}
clubs.ResumeNotifications();
clubs.SuspendNotifications()
For Each item In newItems
clubs.Add(item)
Next item
clubs.ResumeNotifications()
Methods
AddRange: Adds the elements of the specified collection to the end of the RadObservableCollection. You can use this method to perform a bulk add operation.
InsertRange: Inserts the elements of the specified collection at the specified index. You can use this method to perform a bulk add operation, starting at the specified index.
RemoveRange: Removes the elements of the specified collection from the RadObservableCollection. You can use this method to perform a bulk remove operation.
It is important to note that all three of the above methods will call the ResumeNotifications method, even if notifications were previously suspended manually.
SuspendNotifications: Suspends the notifications. You can use this when you're about to add a large number of new items and do not want to raise the CollectionChanged event for each item.
ResumeNotifications: Resumes the notifications. You can use this once you're finished with adding the new items.
Calling the ResumeNotifications method after adding items to the collection with suspended notifications raises the CollectionChanged event with NotifyCollectionChangedAction.Reset.
- Reset: Raises the CollectionChanged event with NotifyCollectionChangedAction.Reset.
Properties
- NotificationsSuspended: Gets a value indicating whether change notifications are suspended.
There is also a public read-only property called ShouldResetOnResumeNotifications. It gets a value that indicates whether RadObservableCollection would raise CollectionChanged event with Reset action, when a bulk add/remove operation takes place. This API is internal and this behavior cannot be changed. The property value is set to true which means that calling ResumeNotifications will always use the Reset action.
Events
-
CollectionChanging: Occurs when collection is changing - i.e., an item is being added/removed. The CollectionChangingEventArgs of the event handler holds the following properties:
Action: Gets or sets the collection change action. It is of type CollectionChangeAction.
Cancel: Set this to True to cancel the changes.
Index: Gets or sets the index of the current item being added/removed.
Item: Gets or sets the currently added/removed item.
PropertyChanged: Occurs when a property value changes.
ObservableItemCollection
ObservableItemCollection extends RadObservableCollection by exposing the ItemChanged event. It is raised when one of the properties of the items present in the collection is changed.
ItemChanged: The event provides the following properties:
- Item: Gets the item that has changed.
- PropertyName: Gets the name of the property that has changed.