c# - Which .Net collection for adding multiple objects at once and getting notified?

Question

Was considering the System.Collections.ObjectModel ObservableCollection<T> class. This one is strange because

• it has an Add Method which takes one item only. No AddRange or equivalent.
• the Notification event arguments has a NewItems property, which is a IList (of objects.. not T)

My need here is to add a batch of objects to a collection and the listener also gets the batch as part of the notification. Am I missing something with ObservableCollection ? Is there another class that meets my spec?

Update: Don't want to roll my own as far as feasible. I'd have to build in add/remove/change etc.. a whole lot of stuff.

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Related Q:
https://stackoverflow.com/questions/670577/observablecollection-doesnt-support-addrange-method-so-i-get-notified-for-each

Answer 1

It seems that the INotifyCollectionChanged interface allows for updating when multiple items were added, so I'm not sure why ObservableCollection<T> doesn't have an AddRange. You could make an extension method for AddRange, but that would cause an event for every item that is added. If that isn't acceptable you should be able to inherit from ObservableCollection<T> as follows:

public class MyObservableCollection<T> : ObservableCollection<T>
{
    // matching constructors ...

    bool isInAddRange = false;

    protected override void OnCollectionChanged(NotifyCollectionChangedEventArgs e)
    {
        // intercept this when it gets called inside the AddRange method.
        if (!isInAddRange) 
            base.OnCollectionChanged(e);
    }


    public void AddRange(IEnumerable<T> items)
    {
         isInAddRange = true;
         foreach (T item in items)
            Add(item);
         isInAddRange = false;

         var e = new NotifyCollectionChangedEventArgs(
             NotifyCollectionChangedAction.Add,
             items.ToList());
         base.OnCollectionChanged(e);
    }
}