CODEWITHSUNDEEP
c#linq
Jason D
Jason D

Reputation: 2664

Linq filtering causes property to not update view

I have the following property that I would like to use Linq to filter. This allows the binding in my view to update the UI just fine:

public ObservableCollection<Worker> Workers
{
    get { return DataManager.Data.MasterWorkerList; }
}

These solutions were suggested in another post, but they don't allow the view to update:

get { return new ObservableCollection<Worker>(DataManager.Data.MasterWorkerList.Where(w => w.Known != true)); }

and

get
{
    var workerList = DataManager.Data.MasterWorkerList.Where(w => w.Known != true);
    return workerList.ToObservableCollection<Worker>();
}

DataManager is a Singleton class and Data is its instance. How can I use Linq filtering in this property without throwing off the UI updating?

Upvotes: 1

Views: 78

Answers (1)

MBender
MBender

Reputation: 5650

While this isn't really "using LINQ filtering", if you're using ObservableCollection you can use a PagedCollectionView to add a filter to the collection.

        PagedCollectionView items = new PagedCollectionView(Workers);
        items.Filter = (o) => (o as Worker).Known != true;

Then bind to items.

The problem with LINQ is that it creates a new collection, and so it breaks bindings. It's still possible to use it, but it can be a bit tiresome. Let me know if the above isn't what you need, and I'll try to figure something else out. ;)

EDIT: PagedCollectionView is only available in Silverlight. If you're using WPF, then you can try something like this:

        ICollectionView items = CollectionViewSource.GetDefaultView(Workers);
        items.Filter = (o) => (o as Worker).Known != true;

Also, I recommend this article on how to display data in WPF (including sorting, filtering and such).

Upvotes: 1

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