ReactiveUI ReactiveList和DependencyProperty

Question

我正在使用ReactiveUI ReactiveLists，在我的项目中，其中一个ReactiveLists在我的自定义WPF MultiSelectComboBox中绑定到ItemsSource DependencyProperty：

<CustomControls:MultiSelectComboBox x:Name="CountriesCombobox" 
                        Width="200"
                        VerticalContentAlignment="Center" 
                        ItemsSource="{Binding Repository.Countries}"
                        SelectedItems="{Binding Repository.SearchViewSelectedCountries, Mode=TwoWay}"/>

...

public static readonly DependencyProperty ItemsSourceProperty =
         DependencyProperty.Register("ItemsSource", typeof(IEnumerable<object>), typeof(MultiSelectComboBox), new FrameworkPropertyMetadata(null,
    new PropertyChangedCallback(MultiSelectComboBox.OnItemsSourceChanged)));

public static readonly DependencyProperty SelectedItemsProperty =
     DependencyProperty.Register("SelectedItems", typeof(IEnumerable<object>), typeof(MultiSelectComboBox), new FrameworkPropertyMetadata(null,
 new PropertyChangedCallback(MultiSelectComboBox.OnSelectedItemsChanged)));

public IEnumerable<object> SelectedItems
{
    get { return (IEnumerable<object>)GetValue(SelectedItemsProperty); }
    set { SetValue(SelectedItemsProperty, value); }
}

public IEnumerable<object> ItemsSource
{
    get { return (IEnumerable<object>)GetValue(ItemsSourceProperty); }
    set { SetValue(ItemsSourceProperty, value); }
}

在我的ComboBox SetSelectedItems方法中选择一个选项后，调用：

private void SetSelectedItems()
{
    if (SelectedItems == null)
        SelectedItems = new List<object>();

    foreach (Node node in _nodeList)
    {
        if (node.IsSelected && node.Title != "All")
        {
            if (this.ItemsSource.Count() > 0)
            {
                var temp = SelectedItems.ToList();
                temp.Add(this.ItemsSource.First(x => x.ToString() == node.Title));
                SelectedItems = SelectedItems.Concat(temp);
            }
        }
    }
}

我在尝试将SelectedItems添加到SelectedItemsProperty，我遇到的问题是如果我的ItemsSourceProperty类型不同IEnumerable绑定不起作用，属性为空（我尝试了类型：List，IList，ICollection，ReactiveList，IReactiveList），如果它是IEnumerable {当我尝试将System.InvalidCastException转换为列表时抛出{1}}：

SelectedItems

如果我尝试使用上面示例的Concat方法，则var temp1 = (List<object>)SelectedItems; 设置为SelectedItems。所以我的问题是，如果将{+ 1}}绑定到null，我该如何添加商品？

它是根据this文章创建的。

Answer 1

嗯，在我使用IList interface：

之后，它工作了

public static readonly DependencyProperty ItemsSourceProperty =
         DependencyProperty.Register("ItemsSource", typeof(IList), typeof(MultiSelectComboBox), new FrameworkPropertyMetadata(null,
    new PropertyChangedCallback(MultiSelectComboBox.OnItemsSourceChanged)));

public static readonly DependencyProperty SelectedItemsProperty =
        DependencyProperty.Register("SelectedItems", typeof(IList), typeof(MultiSelectComboBox), new FrameworkPropertyMetadata(null,
    new PropertyChangedCallback(MultiSelectComboBox.OnSelectedItemsChanged)));

public IList ItemsSource
{
    get { return (IList)GetValue(ItemsSourceProperty); }
    set { SetValue(ItemsSourceProperty, value); }
}

public IList SelectedItems
{
    get { return (IList)GetValue(SelectedItemsProperty); }
    set { SetValue(SelectedItemsProperty, value); }
}

然后：

private void SetSelectedItems()
{
    SelectedItems.Clear();

    foreach (Node node in _nodeList)
    {
        if (node.IsSelected && node.Title != "All")
        {
            if (this.ItemsSource.Count > 0)
                SelectedItems.Add(this.ItemsSource.Cast<object>().ToList().First(x => x.ToString() == node.Title));
        }
    }
}