C#/WINUI3：使用 OrderBy() 到 ObservableCollection 后数据绑定变得无效

Question

Part of the.xaml:

...
<ListView x:Name="DeviceList" ItemsSource="{x:Bind ViewModel.FliteredDevicesCollection,Mode=TwoWay}">
                            <ListView.ItemTemplate>
                                <DataTemplate x:DataType="local1:BleDevice">
...
                                </DataTemplate>
                            </ListView.ItemTemplate>
                        </ListView>
...

I created a custom class named BleDivice , and I bind the ItemsSource of the ListView to ObservableCollection<BleDevice> FliteredDevicesCollection to show the devices in the collection. The device list can be updated with the collection dynamically, which worked well.

Then I tried to reorder the devices in the collection I used FliteredDevicesCollection = new ObservableCollection<BleDevice>(FliteredDevicesCollection.OrderBy(BleDevice => BleDevice.SignalStrength)); , however, the bind became invalid.

I printed the contents in the collection through Debug and found that it was indeed reordered, but the items in the listview no longer changed with the data in the collection. It seemed that the data binding had failed.

Is it caused by this method OrderBy() ? I tried the indirect way, but it still didn't solve the problem. So what is the reason and how to solve this problem, instead of using methods such as DeviceList.ItemsSource = ViewModel.FliteredDevicesCollection;in the.xaml.cs file after each reordering to rebind the data.

New

 private ObservableCollection<BleDevice> flierDevicesCollection { get; set; } = new();

    public ObservableCollection<BleDevice> FliteredDevicesCollection
    {
        get => flierDevicesCollection;
        set
        {
            flierDevicesCollection = value; 
            OnPropertyChanged("FliteredDevicesCollection");
        }
    }

public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

I have already added the code above, but it doesn't work. It is strange that I can add objects to the collection or remove objects from the collection FliteredDevicesCollection.Add(bleDevice); , the ListView is updated normally, but I can't reorder the objects in the collection. These should all send notifications. Actually, the reorder progress has been done, but the binding between them failed, and the result couldn't be shown in the ListView. So what's the reason?

Answer 1

You don't show how you define your FliteredDevicesCollection property, but taking a wild guess I'd say it doesn't notify on property changes, which is correct. What you're doing is a lazy anti-pattern.

What you should be doing is to bind to a CollectionViewSource , and set up filtering and/or ordering using the respective properties of that object. That is literally why that object exists in all XAML frameworks.