ItemsSource到TreeView的SelectedItem属性

Question

我正在创建我的第一个WPF应用程序（之前已经使用WinForms完成了一些操作），并且我开始喜欢它（即使它有时增加了不必要的复杂性。）。 但是我遇到了一个我无法真正解决的问题。

问题：我有一个TreeView和一个伴随的GroupBox，具有选定（第二级）项目的属性。 这些属性在TextBoxes中可编辑（绑定到SelectedItem。[Property]），并且可以正常工作。 但是属性之一是一个列表（定义为ObservableCollection），我想在ComboBox中显示它，因此我将ItemsSource绑定到TreeView的SelectedItem.Modes：

<ComboBox Name="FixtureModesListBox" ItemsSource="{Binding ElementName=FixturesTreeView, Path=SelectedItem.Modes}" ItemTemplate="{StaticResource FixtureModeTemplate}" />

这显然是行不通的，我得到的错误是这样说的：

 BindingExpression path error: 'Modes' property not found on 'object' ''efcFixtureModel' ...

该属性确实存在，已设置，已公开等。

我当前的解决方案可以通过使用一些代码隐藏（并引用完全相同的“路径”）使其工作：

    private void FixturesTreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        if (FixturesTreeView.SelectedItem is efcFixtureModel) // The 1st level/parent items is of a different type
        {
            FixtureModesListBox.ItemsSource = (FixturesTreeView.SelectedItem as efcFixtureModel).Modes;
        }
    }

我无法解决为什么此方法不起作用的问题，也无法在网上找到任何好的信息。

编辑以包括更多信息：

<TreeView Name="FixturesTreeView" ItemTemplate="{StaticResource FixtureItemTemplate}" SelectedItemChanged="FixturesTreeView_SelectedItemChanged">
</TreeView>

...
        // Assignment of ItemsSource
        FixturesTreeView.ItemsSource = mainWin.Companies;
...

public partial class efcMainWindow : Window
{
    // Definition of Companies
    public ObservableCollection<efcCompany> Companies;

...

// Definition of efcCompany    
public class efcCompany
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Url { get; set; }
    public string Logo { get; set; }
    public int FixtureCount { get { return Fixtures.Count; } }
    public ObservableCollection<efcFixtureModel> Fixtures { get; set; }

    public efcCompany(string name = "", int id = -1, string url = "", string logo = "")
    {
        this.Name = name;
        this.Id = id;
        this.Url = url;
        this.Logo = logo;

        this.Fixtures = new ObservableCollection<efcFixtureModel>();
    }

    public override string ToString()
    {
        return "#" + Id.ToString() + ": " + Name + " (" + Url + ", " + Logo + ")";
    }
}

// Definition of efcFixtureController
public class efcFixtureModel
{
    public int Id { get; set; }
    public int Manufacturer { get; set; }
    public efcFixtureType Type { get; set; }
    public string Name { get; set; }
    public string Image { get; set; }
    public string Description { get; set; }

    public byte TotalChannelCount { get; set; }

    public ObservableCollection<efcFixtureMode> Modes;

    public efcFixtureModel()
    {
        Modes = new ObservableCollection<efcFixtureMode>();
    }

    public override string ToString()
    {
        return "#" + Id.ToString() + ": " + Name + " (" + Type.ToString() + ", " + Image + ", " + Description + ")";
    }
}

Answer 1

您需要将efcFixtureModel.Modes从Field转换为Property：

public ObservableCollection<efcFixtureMode> Modes { get; set; }

请阅读C＃中的属性和变量之间的区别

Answer 2

如前所述，您需要将FixturesTreeView中的SelectedItem绑定到ViewModel中类型为efcFixtureModel的属性。

<TreeView Name="FixturesTreeView" ItemTemplate="{StaticResource FixtureItemTemplate}" SelectedItemChanged="FixturesTreeView_SelectedItemChanged"
SelectedItem="{Binding TreeViewSelectedItem}">
</TreeView>

<ComboBox Name="FixtureModesListBox" ItemsSource="{Binding TreeViewSelectedItem.Modes}" ItemTemplate="{StaticResource FixtureModeTemplate}" />