使用 DynamicData Xamarin.forms 棱镜在集合视图中对数据进行分组

Question

我正在使用 Prism 开发 Xamarin.forms 应用程序。 我正在尝试使用动态数据操作（排序、过滤等）和显示分组数据。 我正在关注这个https://www.xamboy.com/2021/01/20/using-dynamic-data-in-xamarin.forms-part-1/

我的问题是我的 Readonlyobservablecollection _getUsers 没有被填充，请看下面：

private SourceCache<User, string> _sourceCache = new SourceCache<User, string>(x =>x.Id);
private ReadOnlyObservableCollection<ObservableGroupedCollection<string,User, string>> _getUsers;
public  ReadOnlyObservableCollection<ObservableGroupedCollection<string, User, string>> GetUser { get; set; }
public string Gender { get { return _gender; } set { SetProperty(ref _gender, value); OnPropertyChanged(new System.ComponentModel.PropertyChangedEventArgs(nameof(Gender))); } }
private string _gender;

 private async Task GetUsers()
        {
            try
            {
                var users = await _apiService.GetUsers();

                _sourceCache.AddOrUpdate(users);

                Func<User, bool> searchFilter(string text) => user =>
                {
                    return string.IsNullOrWhiteSpace(text) || user.PhoneNumber.ToLower().Contains(text.ToLower()) || user.UserName.ToLower().Contains(text.ToLower()) || user.Name.ToLower().Contains(text.ToLower());
                };

                Func<User, bool> genderFilter(string gender) => user =>
                {
                    return gender == "All"  || user.Gender == gender;
                };

                Func<User, bool> statusFilter(string status) => user =>
                {
                    if(status == "Live")
                    {
                        return user.Active == true;
                    }

                    if (status == "Suspended")
                    {
                        return user.Active == false;
                    }

                    return status == "None"  || user.Payment.StatusMessage.Replace(" ","") == status;
                };

               
                var genderPredicate = this.WhenAnyValue(x => x.Gender)
                                         .Select(genderFilter);

                var filterPredicate = this.WhenAnyValue(x => x.SearchText)
                          .Select(searchFilter);

                var statusPredicate = this.WhenAnyValue(x => x.Status)
                         .Select(statusFilter);

                var sortPredicate = this.WhenAnyValue(x => x.SortBy)
                                   .Select(x => SortExpressionComparer<User>.Ascending(a => a.Name));



                _cleanUp = _sourceCache.Connect()
                           .Filter(genderPredicate)
                           .Group(x => x.Race)
                           .Transform(g => new ObservableGroupedCollection<string, User, string>(g, genderPredicate, sortPredicate))
                           .Bind(out _getUsers)
                           .DisposeMany()
                           .Subscribe();


                Gender = "All";

                OnPropertyChanged(new System.ComponentModel.PropertyChangedEventArgs(nameof(Gender)));

            }
            catch (Refit.ApiException ex)
            {
                if(ex.StatusCode != System.Net.HttpStatusCode.NotFound)
                {
                    await HandleExceptionAsync(ex);
                }
                
            }
            catch (Exception ex)
            {
                await HandleExceptionAsync(ex);
            }
        }

通用 class

 public class ObservableGroupedCollection<TGroupKey, TObject, TKey> : ObservableCollectionExtended<TObject>, IDisposable
    {
        public TGroupKey Key { get; }

        public ObservableGroupedCollection(IGroup<TObject, TKey, TGroupKey> group, IObservable<Func<TObject, bool>> filter, IObservable<IComparer<TObject>> comparer)
        {
            this.Key = group.Key;

            //load and sort the grouped list
            var dataLoader = group.Cache.Connect()
                .Filter(filter)
                .Sort(comparer)
                .ObserveOn(RxApp.MainThreadScheduler)
                .Bind(this) //make the reset threshold large because xamarin is slow when reset is called (or at least I think it is @erlend, please enlighten me )
                .Subscribe();

            _cleanUp = new CompositeDisposable(dataLoader);
        }

        public void Dispose()
        {
            _cleanUp.Dispose();
        }

        private readonly IDisposable _cleanUp;
    }

我真的很挣扎。 如果有人可以提供帮助，我将不胜感激。

Answer 1

您可以使用它来填充_getUsers 。

 public ReadOnlyObservableCollection<ObservableGroupedCollection<string, User, string>> GetUser {

            get
            {
                return _getUsers;
            }
            set
            {
                if (_getUsers != value)
                {
                    _getUsers = value;
                    OnPropertyChanged(nameof(GetUser));
                }
            }
        }