CODEWITHSUNDEEP
wpfsilverlightfiltercollectionviewsource
Berryl
Berryl

Reputation: 12833

CollectionViewSource Filtering Event vs Property

What are some of the practical differences between using the CollectionViewSource.View.Filter property as opposed to the CollectionViewSource.Filter event? Are there situations where you would use one over the other or is it a matter of preference?

Cheers,
Berryl

EDIT: I do see that the docs say "If your view object comes from a CollectionViewSource object, you apply filtering logic by setting an event handler for the Filter event." although nothing stops you from setting the property on the view, and it doesn't say why to do so.

The advantage I have found so far in setting the event on the CollectionViewSource is that you can implement all of your filtering logic in one event handler and then use View.Refresh (or View.DeferRefresh) to invoke it as the user changes filtering criteria.

Upvotes: 2

Views: 1167

Answers (1)

E Mett
E Mett

Reputation: 2302

Setting the Filter event in the CollectionViewSource would mean that the event is called even when there is no filtering needed which would make the process less efficient.

The official way of using the Filter event is by adding it on filtering and removing it later when the filter is cleared.

viewsource.Filter += viewsource_Filter;

Then:

viewsource.Filter -= viewsource_Filter; //how do you know how many events there are!?

If you use the event, you have to make sure that you are not adding the event each time the filter value changes, because apart from having redundant events lurking around (=app works harder for nothing) you will have to remove all the events in order to clear the filter.

Thus, there is an advantage in using the Filter property, because you can more easily clear the filter by setting the property to null.

viewsource.view.Filter = null;

Upvotes: 0

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