从 linq 查询返回 ObservableCollection

Question

I have following linq snippet

Note -> This is Metro App, and ICollectionView does not work as expected for grouping/sorting.

        ObservableCollection<int> ints = new ObservableCollection<int>();
        ints.Add(3);
        ints.Add(4);
        ints.Add(5);
        ints.Add(6);
        ints.Add(3);
        ints.Add(4);
        ints.Add(1);
        ints.Add(2);


        var groupedInts = ints.GroupBy(i=>i).Select(i=>  new {Key=i.Key, Count=i.Count()});

I want following

1. To subscribe to groupedInts or ObservableCollection corresponding to it (basically databinding from WPF/Metro UI to groupInts)

2. Any change in ints (original observablecollection) should be reflected by groupedInts (so that UI subscribing to groupInts/related ObservableCollection can show the changes).

In actual scenario, the data structure is slightly complex (6-7 properties), but the problem boils down to above described issue.

Answer 1

处理ints.CollectionChanged事件并使用相同的 LINQ 查询刷新groupedInts变量...

Answer 2

There's two ways I can think of.

1st : Use Bindable Linq / Continuous Linq

2nd : Create a seperate CollectionView for the groupedInts. When the original collection changes, this should change along with it. Here's a nice and neat tutorial

AngelWPFs idea of Notifying the LINQ property as changed is viable, too.

Answer 3

You need my ObservableComputations library. Using this library you can code like this:

ObservableCollection<int> ints = new ObservableCollection<int>();

ints.Add(3);
ints.Add(4);
ints.Add(5);
ints.Add(6);
ints.Add(3);
ints.Add(4);
ints.Add(1);
ints.Add(2);

var groupedInts = ints.Grouping(i=>i).Selecting(ig =>  new {Key=ig.Key, Count=ig.Count});

groupedInts is ObservableCollection and reflects all the changes in the ints collection.