Question

我有以下XAML：

<StackPanel Orientation="Vertical">
    <TextBox IsReadOnly="True" Text="{Binding SchedulerStatus, Mode=OneWay}" Width="150" VerticalAlignment="Center" Margin="10" />
    <Button Width="75" Height="30" Content="Test" Command="{Binding StartScheduler}" />
</StackPanel>

这是绑定到此视图模型的窗口：

public class SchedulerViewModel : ViewModelBase // ViewModelBase implements INotifyPropertyChanged, using the [CallerMemberName] attribute.
{
    private readonly SchedulerServiceClient _proxy;

    public SchedulerViewModel()
    {
        _proxy = new SchedulerServiceClient();
        SchedulerStatusPoller poller = new SchedulerStatusPoller(this, _proxy);
    }

    private SchedulerStatus _schedulerStatus;
    internal SchedulerStatus SchedulerStatus
    {
        get
        {
            return _schedulerStatus;
        }
        set
        {
            if (value != _schedulerStatus)
            {
                _schedulerStatus = value;
                OnPropertyChanged();
            }
        }
    }
}

SchedulerServiceClient是持续运行的WCF服务的代理，并且具有我需要观察的Status属性。因为我无法在两天后尝试从WCF获得回调，所以我实现了SchedulerStatusPoller，定期轮询WCF状态，并更新viewmodel状态，希望更新WCF状态的显示。

class SchedulerStatusPoller
{
    private static readonly Timer StatusTimer = new Timer(5000);
    private static SchedulerViewModel viewModel;
    private static SchedulerServiceClient proxy;

    public SchedulerStatusPoller(SchedulerViewModel targetViewModel, SchedulerServiceClient proxy)
    {
        SchedulerStatusPoller.proxy = proxy;
        viewModel = targetViewModel;
        StatusTimer.Elapsed += StatusTimerElapsed;
        StatusTimer.AutoReset = true;
        StatusTimer.Enabled = true;
        StatusTimer.Start();
    }

    void StatusTimerElapsed(object sender, ElapsedEventArgs e)
    {
        viewModel.SchedulerStatus = proxy.GetStatus();
    }
}

我在UI（窗口）中直接使用了以下代码，确认PropertyChanged正在引发SchedulerViewModel。抛出异常。

void _viewModel_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
    throw new NotImplementedException();
}

private void ButtonBase_OnClick(object sender, RoutedEventArgs e)
{
    ((SchedulerViewModel)DataContext).SchedulerStatus = SchedulerStatus.Processing;
}

轮询器每五秒调用一次viewmodel上的SchedulerStatus属性，但文本框不会更新。我做错了什么？

Answer 1

你必须提到源触发器

Text="{Binding SchedulerStatus, Mode=OneWay, UpdateSourceTrigger=PropertyChanged}"

Answer 2

Setter中的OnPropertyChanged缺少一个参数。不应该是......像

的PropertyChanged（＆＃34; SchedulerStatus＆＃34）;

Answer 3

也许，你可以像这样编码：

OnPropertyChanged（this，new PropertyChangedEventArgs（“SchedulerStatus”））;

WPF数据绑定UI元素未更新

3 个答案: