单击/打开时，ComboBox停止更新

Question

我有2 ComboBoxes的视图。当在第一个项目中选择一个项目时，将获得第二个项目的列表。链接视图和视图模型的属性如下：

在视图后面的代码中，我链接了视图和视图模型

var viewModel = new MetrologyFileViewModel();
DataContext = viewModel;

WPF：

<ComboBox ItemsSource="{Binding MetrologyProperties}"
          SelectedIndex="{Binding NewSelectedMetrologyPropertyIndex}"
          Grid.Column="1"
          Grid.ColumnSpan="2"
          Style="{StaticResource ComboBoxStyle1}" />
<ComboBox ItemsSource="{Binding NewMetrologyData}"
          SelectedIndex="{Binding NewSelectedMetrologyDataIndex}"
          Grid.Row="1"
          Grid.Column="1"
          Grid.ColumnSpan="2"
          Style="{StaticResource ComboBoxStyle1}" />

C＃：

/// <summary>
/// The new metrology property of the metrology data.
/// </summary>
public int NewSelectedMetrologyPropertyIndex
{
    get { return _newSelectedMetrologyPropertyIndex; }
    set
    {
        _newSelectedMetrologyPropertyIndex = value;

        _newMetrologyData = _newSelectedMetrologyPropertyIndex > 0 ? new ObservableCollection<MetrologyData> { new MetrologyData() }.AddRange(DbServiceMetrologyData.GetOnProperty(MetrologyProperties[_newSelectedMetrologyPropertyIndex])) : null;

         NotifyPropertyChanged();
         NotifyPropertyChanged(nameof(NewMetrologyData));
    }
}

/// <summary>
/// The new available metrology data that can be chosen from.
/// </summary>
public ObservableCollection<MetrologyData> NewMetrologyData
{
    get { return _newMetrologyData; }
    set
    {
        _newMetrologyData = value;
         NotifyPropertyChanged();
    }
}

/// <summary>
/// The new metrology data of the metrology fie.
/// </summary>
public int NewSelectedMetrologyDataIndex
{
    get { return _newSelectedMetrologyDataIndex; }
    set
    {
        _newSelectedMetrologyDataIndex = value;
        NotifyPropertyChanged();
    }
}

AddRange方法：

/// <summary>
/// Add a range of items to a <see cref="ObservableCollection{T}"/>.
/// </summary>
/// <typeparam name="T">The type of the <see cref="ObservableCollection{T}"/></typeparam>
/// <param name="sourceCollection">The <see cref="ObservableCollection{T}"/> where the items have to be added to.</param>
/// <param name="newCollection"><see cref="ObservableCollection{T}"/> with the new items.</param>
    public static ObservableCollection<T> AddRange<T>(this ObservableCollection<T> sourceCollection, ObservableCollection<T> newCollection)
{
    if (newCollection != null)
        foreach (var item in newCollection)
            sourceCollection.Add(item);

    return sourceCollection;
}

我第一次在第一次ComboBox中选择一个属性时，第二次更新很好，虽然视图（我认为）没有完全更新，因为列表应该显示的空间非常小（见图）。

只要我没有点击第二个ComboBox，这就会继续有效。从我打开（点击）第二个ComboBox的那一刻起，当我在第一个中选择一个属性时，它就会停止更新。

更新 我发现只要拨打DbServiceMetrologyData.GetOnProperty(MetrologyProperties[_newSelectedMetrologyPropertyIndex])问题就解决了，我就不知道为什么会这样。

Answer 1

我发现只要调用DbServiceMetrologyData.GetOnProperty(MetrologyProperties[_newSelectedMetrologyPropertyIndex])问题就解决了，我不知道为什么会这样。