Colectiview.deferrefresh () lanza la excepción

Question

Hay casos en los que tiene muchas actualizaciones de la UI, debido a una cantidad masiva de eventos de inotifychangedProperties.En ese caso, es posible que desee indicar los cambios a UI solo una vez cuando todas las propiedades se configuran como en un lote.

Encontré este gran artículo que explica cómo aplazar la actualización de la visualización:

http://marlongegrech.wordpress.com/2008/11/22 / IcollectionView-Explicado /

Sin embargo, obtengo una excepción cuando la vista está diferida e intento agregar algo a la colección.No entiendo por qué esto no debería ser permitido.Ese es todo el punto de ello en primer lugar.

InvalidOparationException: No puede cambiar o verificar el contenido o la posición actual de CollectiveView mientras se actualiza se está aplazando.

¿Alguien sabe cómo resolver este problema? Muchas gracias,

Answer 1

Yes, don't modify the collection in question. I think that you are misunderstanding the purpose of a collection view. This is what MSDN says;

You can think of a collection view as a layer on top of a binding source collection that allows you to navigate and display the collection based on sort, filter, and group queries, all without having to manipulate the underlying source collection itself.

So in short, don't defer the refresh until you are done adding and removing, and otherwise manipulating your collection.

Answer 2

I think you are misunderstanding or misrepresenting the MSDN help on the subject. They are saying that you don't have to modify the underlying collection to sort or filter. They are not saying that you can't modify the underlying collection. The OP has a very valid point. We have a large collection that has been sorted and filter for the user and it is displayed in a list box. When the user selects a range of those records and wants to delete them, we are forced into a situation where the ListCollectionView refreshs view for every item that was deleted.

I think the OP's question is very valid. The performance is horrendous because we have multiple filters on a huge set of data. The DeferRefresh has a real purpose on a class like the ListCollectionView, but in inexplicably diabled for inserts and deletes, when you need it the most.