在 MVVM 中，是否可以在视图的代码隐藏中访问视图模型？

Question

在 MVVM 模式中，是否可以接受甚至可能访问视图代码隐藏中的 ViewModel 属性？

我有一个可观察的集合，它填充在视图模型中。我需要在视图中使用它来绑定到带有链表的无尽股票代码。即

    private LinkedList<Border> tickerForex = new LinkedList<Border>();
    public ForexBuy()
    {
        InitializeComponent();
        DataContext = new ForexViewModel();
    }
    private void InitializeForexTicker()
    {
        CanvasForexBuyTicker.Children.Clear();
        foreach (var currency in DataContext.Currencies) //Is this possible/allowable???
        {
           AddTickerItem(currency);
        }
        CanvasForexBuyTicker.Dispatcher.BeginInvoke(DispatcherPriority.Background, new DispatcherOperationCallback(delegate
        { var node = tickerForex.First;
            while (node != null)
            {
                if (node.Previous != null)
                {
                    Canvas.SetLeft(node.Value, Canvas.GetLeft(node.Previous.Value) + node.Previous.Value.ActualWidth + gap);
                }
                else
                {
                    Canvas.SetLeft(node.Value, CanvasForexBuyTicker.Width + gap);
                }
                node = node.Next;
            }
            return null;
        }), null);
}
void AddTickerItem(Currency currency)
    {
        Border border = new Border();
        border.Background = new SolidColorBrush(Color.FromArgb(255, 0, 99, 99));
        if (currency.IsUpward == 0)
        {
            border.Background = new SolidColorBrush(Color.FromArgb(255, 255, 153, 0));
        }
        border.BorderThickness = new Thickness(3);
        border.BorderBrush = new SolidColorBrush(Colors.White);
        border.CornerRadius = new CornerRadius(10);
        border.Width = Double.NaN;
        border.Height = 35;
        UIHelper.CanvasAutoSize canvas = new UIHelper.CanvasAutoSize();
        canvas.Background = Brushes.Green;  
        canvas.Tag = currency;
        canvas.Height = Double.NaN;
        TextBlock tb = new TextBlock
        {
            Text = currency.Code + " " + currency.Sell + " ",
            FontSize = 22,
            FontWeight = FontWeights.Bold,
            Foreground = Brushes.Black
        };
        tb.SetValue(Canvas.LeftProperty, 8d);
        tb.SetValue(Canvas.TopProperty, 2d);
        canvas.Children.Add(tb);
        tb.TouchDown += TouchTickerItem;
        border.Child = canvas;
        CanvasForexBuyTicker.Children.Add(border);
        Canvas.SetTop(CanvasForexBuyTicker, 3);
        Canvas.SetLeft(CanvasForexBuyTicker, 0);
        tickerForex.AddLast(border);
    }

对于调度程序是否应该从 ViewModel 触发或是否在视图代码隐藏中使用它，我有点迷茫。

Answer 1

如果问题只是关于如何从代码隐藏访问 ViewModel，您可以简单地将 DataContext 转换为正确的类型：

var viewModel = (MyViewModel)DataContext;
foreach (var currency in viewModel.Currencies)
{
    ...
}

这是否可以接受是一个品味问题。我认为通过视图的 XAML 中的绑定或通过一段代码隐藏来访问视图模型没有任何根本区别。

Answer 2

简短回答：否。

您不应该将业务或模型特定的代码放在后面的代码中。只有特定于 VIEW 的代码才应放在代码隐藏中。

你为什么要宣布List<Border>.对我来说听起来很奇怪。你到底想做什么？