Question

我正在尝试使用MVVM Light将数据绑定到网格。如果我执行以下操作，它将起作用：

public class GuidePageViewModel : ViewModelBase
{
    private ObservableCollection<SimpleChannelData> _simpleChannelDataList;
    private IChannelDataService _channelDataService;

    public GuidePageViewModel(IChannelDataService channelDataService)
    {
        _channelDataService = channelDataService;

        ATest(); // Create data synchronously here
    }

    private void ATest()
    {
        SimpleChannelDataList = new ObservableCollection<SimpleChannelData>();

        var record = new SimpleChannelData()
        {
            Cn = 120,
            Csign = "Hey",
            Hd = "Y",
            Index = 1,
            Premium = "y",
            TrbId = 9
        };

        SimpleChannelDataList.Add(record);
    }

    private async void Start()
    {
        await LoadChannelData();
    }

    private async Task LoadChannelData()
    {
        SimpleChannelDataList = new ObservableCollection<SimpleChannelData>((await _channelDataService.GetChannelData()));
        RaisePropertyChanged(() => SimpleChannelDataList);
    }

    #region Public Properties

    public ObservableCollection<SimpleChannelData> SimpleChannelDataList
    {
        get
        {
            return _simpleChannelDataList;
        }
        set
        {
            if (Set(() => SimpleChannelDataList, ref  _simpleChannelDataList, value))
            {
                RaisePropertyChanged(() => SimpleChannelDataList);
            }

        }
    }
    #endregion
}

现在，如果我将构造函数更改为以下代码，使用对Start的异步调用，则网格不会获取数据：

public GuidePageViewModel(IChannelDataService channelDataService)
{
    _channelDataService = channelDataService;
    Start();
}

我知道这种异步问题，但我无法弄清楚。有人可以指出我做错了吗？

Answer 1

首先，您不应该在constructor中调用异步方法。尝试更改逻辑，以便不需要该调用。

同时，请尝试检查AsyncMVVM。它包含一些有趣的模式，可以在异常的情况下检索数据，同时暴露通常的MVVM接口。

MVVM Light的异步绑定问题

1 个答案: