Question

我是MVVM的新手并且一直试图将工作程序转换为MVVM程序。我一直在寻找答案，但到目前为止还没有运气。

基本上我拥有的是：列表框和列表视图。列表框中填充了Trainstations，我想在列表视图中显示站点的时间（有延迟等）。列表框中充满了工作站，每当我选择一个工作站时，它都会更新，我将它放在一个名为“CurrentStation”的变量中。现在我正在使用这个'CurrentStation'来获取该站所有离开的ObservableCollection列表，但由于某种原因，该功能只被调用一次，当我选择另一个站时不会更新。

我也不知道在xaml代码中绑定什么。

<ListBox x:Name="lstStations" Margin="8" Grid.Row="1" ItemsSource="{Binding StationList}" SelectedItem="{Binding CurrentStation}" DisplayMemberPath="Name"/>
        <ListView Grid.Column="1" Margin="8" Grid.Row="1" ItemsSource="{Binding Departures}" >
            <ListView.View>
                <GridView>
                    <GridViewColumn DisplayMemberBinding="{Binding Time, StringFormat=t}" Header="Time" />
                    <GridViewColumn DisplayMemberBinding="{Binding Delay, Converter={StaticResource mijnDelayConverter}}" Header="Delay"/>
                    <GridViewColumn DisplayMemberBinding="{Binding Station}" Header="Station"/>
                    <GridViewColumn DisplayMemberBinding="{Binding Vehicle}" Header="Vehicle"/>
                    <GridViewColumn Header="Platform" CellTemplate="{DynamicResource dataTemplateTextblock}" />
<!-- Haven't had the chance to look at this ^ I don't think this is correct though -->
                    </GridView>
                </ListView.View>
            </ListView>

这是ViewModel代码：

        public string Name
        {
            get
            {
                return "MainPage"; 
            }
        }
        public ObservableCollection<Station> StationList
        {
            get
            {
                return Station.GetStations();
            }
        }
        private Station _currentStation;
        public Station CurrentStation
        {
            get
            {
                return _currentStation;
            }
            set
            {
                _currentStation = value;
                Console.WriteLine("New station selected: " + _currentStation.ToString());
                OnPropertyChanged("CurrentStation");
            }
        }
        private ObservableCollection<Departure> _departures;
        public ObservableCollection<Departure> Departures
        {
            get
            {
                return Departure.GetDepartures(CurrentStation);
            }
            set
            {
                _departures = value;
            }
        }

Answer 1

我认为你需要：

明确更新Departures属性，可以在CurrentStation setter中完成

private Station _currentStation;
public Station CurrentStation
{
    get
    {
        return _currentStation;
    }
    set
    {
        _currentStation = value;
        Departures = Departure.GetDepartures(_currentStation);
        Console.WriteLine("New station selected: " + _currentStation.ToString());
        OnPropertyChanged("CurrentStation");
    }
}

触发更改通知，该更改通知将使用着名的OnPropertyChanged

刷新离场绑定（和列表框！）

private ObservableCollection<Departure> _departures;
public ObservableCollection<Departure> Departures
{
    get
    {
        return _departures
    }
    set
    {
        _departures = value;
        OnPropertyChanged("Departures");
    }
}

Answer 2

您必须将Observable集合上的OnPropertyChanged设置为

public ObservableCollection<Departure> Departures
    {
        get
        {
            return Departure.GetDepartures(CurrentStation);
        }
        set
        {
            _departures = value; OnPropertyChanged("Departures")
        }
    }

mvvm绑定selecteditem以更新listview

2 个答案: