将轮询 Web 服务转换为 RX

Question

给定：

public partial class Weather
{
    private readonly DispatcherTimer _timer = new DispatcherTimer();
    private readonly IWeatherDataProvider _weatherDataProvider;
    public Weather(IWeatherDataProvider weatherDataProvider)
    {
        InitializeComponent();
        _weatherDataProvider = weatherDataProvider;
        Loaded += async (sender, args) =>
        {
            _timer.Interval = new TimeSpan(0, 15, 0);
            _timer.Tick += async (o, eventArgs) => DataContext = await UpdateWeather();
            _timer.Start();
            DataContext = await UpdateWeather();
        };
        Unloaded += (sender, args) => _timer.Stop();
    }
    private async Task<WeatherData> UpdateWeather()
    {
        var weatherData = await _weatherDataProvider.GetWeather();
        return weatherData;
    }
}

我很困惑如何转换这个使用反应式扩展。我从：

var weather = Observable.FromAsync(_weatherDataProvider.GetWeather);

但是当我进入投票部分时：

Observable.Timer(new TimeSpan(0, 15, 0)).Subscribe(weather);

没有通用重载。我想我明白我需要生成一个序列的想法，但由于某种原因我无法弄清楚它。

Answer 1

具有

Select投影的Observable.Interval是关键。像这样：

public class Weather
{
    private readonly IWeatherDataProvider _weatherDataProvider;        
    private CompositeDisposable disposables = new CompositeDisposable();
    public Weather(IWeatherDataProvider weatherDataProvider)
    {
        InitializeComponent();
        _weatherDataProvider = weatherDataProvider;
        Loaded += (sender, args) =>
        {
          var weather = Observable.Interval(TimeSpan.FromMinutes(15))
              .SelectMany(_ => weatherDataProvider.GetWeather().ToObservable())
              .ObserveOnDispatcher()
              .Subscribe(data => DataContext = data);
          disposables.Add(weather);
        };
        Unloaded += (sender, args) => disposables.Dispose();
    }
}

ObserveOnDispatcher 位于 nuget 包 rx-xaml 中。