Helper to integrate CommunityToolkit.Mvvm.Input.IRelayCommand with WPF CommandManager

RelayCommandHelpers.cs

using System;
using System.Collections.Generic;
using System.Windows.Input;
using CommunityToolkit.Mvvm.Input;

public static class RelayCommandHelpers
{
    private static readonly List<WeakReference<IRelayCommand>> _commands = new();

    public static void RegisterCommandsWithCommandManager(object container)
    {
        if (_commands.Count == 0)
            CommandManager.RequerySuggested += OnRequerySuggested;

        foreach (var p in container.GetType().GetProperties())
        {
            if (p.PropertyType.IsAssignableTo(typeof(IRelayCommand)))
            {
                var command = (IRelayCommand?)p.GetValue(container);
                if (command != null)
                    _commands.Add(new WeakReference<IRelayCommand>(command));
            }
        }
    }

    private static void OnRequerySuggested(object? sender, EventArgs args)
    {
        foreach (var command in _commands)
        {
            if (command.TryGetTarget(out var c))
                c.NotifyCanExecuteChanged();
        }
    }
}

To use, call this method from the constructor of a WPF view model that has IRelayCommand properties:

public class MyViewModel : ObservableObject
{
    public IRelayCommand SomeCommand { get; }

    public MyViewModel()
    {
        SomeCommand = new AsyncRelayCommand(() => DoStuffAsync(), () => true);

        RelayCommandHelpers.RegisterCommandsWithCommandManager(this);
    }
}