绑定到过滤后的可观察集合

Question

I have an observable collection of type A .

Class A contains an enum - IsWhite .

My observable collection is called ACollection .

I also have 2 datagrids, one that will have an itemssource bound to ACollection where the A items have IsWhite set to false, the other datagrid which is bound to the same collection but with IsWhite set to true.

How can I achieve this?

The collection is declared as follows;

ObservableCollection<A> ACollection = new ObservableCollection<A>;

and the class

public class A
{
    IsWhite isWhiteEnum { get; set; } = IsWhite.False;
}

I want one datagrid itemssource to bind to ACollection populating the items where IsWhite is False and the other datagrid itemssource to bind to ACollection popualting items where IsWhite is True .

Answer 1

Here's a precis of the relevent parts of the article here:

https://social.technet.microsoft.com/wiki/contents/articles/26673.wpf-collectionview-tips.aspx

You don't want to filter the default view of a collection because that way your filter would apply to both datagrids.

This bit of code gets two independent views:

PeopleView = (CollectionView)new CollectionViewSource { Source = People }.View;
LevelsPeopleView = (CollectionView)new CollectionViewSource { Source = People }.View;

People is an observablecollection of person.

Both those views are collectionviews, eg.

 public CollectionView LevelsPeopleView { get; set; }

The views are bound in TwoCollectionViews.xaml eg

    <DataGrid ....
              ItemsSource="{Binding PeopleView}"

And the article illustrates various filters such as the msdn approach:

private void ShowOnlyBargainsFilter(object sender, FilterEventArgs e)
{
AuctionItem product = e.Item as AuctionItem;
if (product != null)
{
    // Filter out products with price 25 or above
    if (product.CurrentPrice < 25)
    {
        e.Accepted = true;
    }
    else
    {
        e.Accepted = false;
    }
}
}

Or much more sophisticated approaches.

You set a filter:

            LevelsPeopleView.Filter = FirstOfLevel_Filter;

If the view has already grabbed the data out that collectionview then nothing will happen. You need to also do

         LevelsPeopleView.Refresh();

This sort of filtering is quite inefficient and linq is better at large datasets. Still better is small datasets. Unless your users really really like scrolling.