绑定 WPFToolkit 图表时出现 System.NullReferenceException答案

【问题标题】：System.NullReferenceException when binding WPFToolkit chart绑定 WPFToolkit 图表时出现 System.NullReferenceException
【发布时间】：2012-03-26 11:10:06
【问题描述】：

只要我在视图模型上的属性包含数据，WPFToolkit 就会抛出异常，但当它为空时不会！

查看：

<UserControl x:Class="ChartView"
    xmlns:DV="clr-namespace:System.Windows.Controls.DataVisualization;assembly=System.Windows.Controls.DataVisualization.Toolkit"
    xmlns:DVC="clr-namespace:System.Windows.Controls.DataVisualization.Charting;assembly=System.Windows.Controls.DataVisualization.Toolkit"
<Grid>
    <DVC:Chart>
        <DVC:Chart.Series>
            <DVC:ScatterSeries ItemsSource="{Binding Data}"
                               DependentValueBinding="{Binding Path=Value}"
                               IndependentValueBinding="{Binding Path=Key}" />
        </DVC:Chart.Series>
    </DVC:Chart>
</Grid>

视图模型：

public class ChartViewModel  
{
    public ObservableCollection<KeyValuePair<int, int>> Data { get; set; }

    public ChartViewModel()
    {
        Data = new ObservableCollection<KeyValuePair<int, int>>();

        //If I uncomment this, the error is thrown upon binding
        //Data.Add(new KeyValuePair<int, int>(1, 10));
    }
}

堆栈跟踪的顶部是：

at System.Windows.Controls.DataVisualization.Charting.ScatterSeries.UpdateDataPoint(DataPoint dataPoint) in C:\dd\WPF_1\src\wpf\src\ControlsPack\WPFToolkit\DataVisualization\Charting\Series\ScatterSeries.cs:line 179
at System.Windows.Controls.DataVisualization.Charting.DataPointSeriesWithAxes.OnDataPointActualIndependentValueChanged(DataPoint dataPoint, Object oldValue, Object newValue) in C:\dd\WPF_1\src\wpf\src\ControlsPack\WPFToolkit\DataVisualization\Charting\Series\DataPointSeriesWithAxes.cs:line 257
at System.Windows.Controls.DataVisualization.Charting.DataPointSeries.OnDataPointActualIndependentValueChanged(Object sender, RoutedPropertyChangedEventArgs`1 args) in C:\dd\WPF_1\src\wpf\src\ControlsPack\WPFToolkit\DataVisualization\Charting\Series\DataPointSeries.cs:line 1322
at System.Windows.Controls.DataVisualization.Charting.DataPoint.OnActualIndependentValuePropertyChanged(Object oldValue, Object newValue) in C:\dd\WPF_1\src\wpf\src\ControlsPack\WPFToolkit\DataVisualization\Charting\DataPoint\DataPoint.cs:line 657
at System.Windows.Controls.DataVisualization.Charting.DataPoint.OnActualIndependentValuePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) in C:\dd\WPF_1\src\wpf\src\ControlsPack\WPFToolkit\DataVisualization\Charting\DataPoint\DataPoint.cs:line 629

【问题讨论】：

标签： mvvm wpftoolkit

【解决方案1】：

解决方案非常牵强。在我的 App.xaml.cs 中，为了本地化（我希望逗号作为小数点），我更改了语言：

using System.Windows.Markup;
using System.Globalization;


var window = new MainWindowView();
window.Language = XmlLanguage.GetLanguage(CultureInfo.CurrentCulture.IetfLanguageTag);
window.Show();

显然，WPFToolkit 不喜欢这样。

【讨论】：