uwp limit the number of items in AdvancedCollectionView

Question

I have two advanced collection views from windows community toolkit and both of them are bound to same ObservableCollection with different filters and sorting, basically in one of them I need to show just the recent and limited number of items. How can I achieve that?

PeoplePrivate = new ObservableCollection<Person>();

        var People = new AdvancedCollectionView(PeoplePrivate, true) { Filter = x => true };
        People.SortDescriptions.Add(new SortDescription(nameof(Person.Name), SortDirection.Ascending));

        var RecentPeople = new AdvancedCollectionView(PeoplePrivate, true) { Filter = x => true };
        RecentPeople.SortDescriptions.Add(new SortDescription(nameof(Person.Modified), SortDirection.Descending));

As you can see in the code above recentPeople should only show recent 20 people according to the modified date. There doesn't seem to be any property to set max size on the advancedCollection view or do anything like "Take(20)".

I tried to return a new advancedCollection by creating a IEnumerable first with Take(20) but that doesn't look the right way because I need to keep it linked to the same ObservableCollection.

This would be an interesting feature. I've also been toying with a different wrapper for ObservableCollection for another use-case, but part of that work could also serve this use-case. Could you file an issue on the Toolkit repo here? https://github.com/windows-toolkit/WindowsCommunityToolkit/issues/new — Michael Hawker - MSFT, Apr 25 '19 at 17:31

score 1 · Answer 1 · answered Apr 01 '19 at 08:10

1

view or do anything like "Take(20)" I tried to return a new advancedCollection by creating a IEnumeralbe first with Take(20)

Currently AdvancedCollectionView has not provide this method to get recent number items. But you could remove all the items except top 20 of the source.

public static class AdvancedCollectionViewEx
{
    public static void GetTopRang(this AdvancedCollectionView acv, int Range)
    {
        do
        {
            var LastIndex = acv.Source.Count - 1;
            acv.Source.RemoveAt(LastIndex);

        } while (acv.Source.Count > Range);
    }
}

Usage

RecentPeople.GetTopRang(20);

answered Apr 01 '19 at 08:10

Nico Zhu

32,367
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this only works when I call this extension method, it doesnt automatically sync the data like filter or sort – Muhammad Touseef Apr 01 '19 at 17:36
Yep, you need call this method after data sort. So I create this extension method. – Nico Zhu Apr 02 '19 at 02:11
that is helpful but not the answer I am looking for, thanks though – Muhammad Touseef Apr 02 '19 at 09:09

score 0 · Answer 2 · answered Apr 25 '19 at 17:34

0

I like the WPF answer provided here and use a Binding Converter to chop the end-result of the collection view when it's bound to the ListView. Then it should get updated when the collection changes and re-filter?

answered Apr 25 '19 at 17:34

Michael Hawker - MSFT

1,572
12
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uwp limit the number of items in AdvancedCollectionView

2 Answers2