c# - MVVM Caliburn.micro 组合框 Country-City 无法正常工作

Question

我正在将 MVVM 与 Caliburn.Micro 一起使用，但我遇到了问题。
所以我有 2 个组合框。首先是代表国家列表，其次是城市。我希望只要第一个列表中的国家/地区发生更改，城市列表就会更新，并带有相应的城市列表。我的问题是城市列表没有更新。
这是我的代码:

public class MyViewModel : PropertyChangedBase
{
    Company company = new Company();
    List<string> countries = new List<string> {"USA","Germany" };
    public string Name
    {
        get { return company.name; }
        set { company.name = value;
        }
    }
    public List<string> Countries
    {
        get { return countries; }
        set {
            company.country = ToString();
            NotifyOfPropertyChange(() => Countries);
            NotifyOfPropertyChange(() => Cities);
        }
    }
    public List<string> Cities
    {
        get {
            switch (company.country)
            {
                case "USA": return new List<string> { "New York", "Los Angeles" };  
                case "Germany": return new List<string> { "Hamburg", "Berlin" };
                default: return new List<string> { "DEFAULT", "DEFAULT" };

            }
            }
        set { company.city = value.ToString();
            NotifyOfPropertyChange(() => Cities);
        }
    }

}

现在城市列表保留默认成员(DEFAULT，DEFAULT)。该 View 仅包含 2 个具有相应名称的组合框:

<Grid>
        <ComboBox x:Name="Countries" />
        <ComboBox x:Name="Cities" />
</Grid>

一些建议？
对不起，我的英语不好。

Answer 1

绑定(bind)SelectedItem国家属性(property)ComboBox到 View 模型的源属性:

<ComboBox x:Name="Countries" ItemsSource="{Binding Countries}" SelectedItem="{Binding SelectedCountry}" />
<ComboBox x:Name="Cities" ItemsSource="{Binding Cities}" />

...并提高 PropertyChanged Cities 的事件这个 setter 中的属性:

public class MyViewModel : PropertyChangedBase
{
    Company company = new Company();
    List<string> countries = new List<string> { "USA", "Germany" };
    public string SelectedCountry
    {
        get { return company.country; }
        set
        {
            company.country = value;
            NotifyOfPropertyChange(() => SelectedCountry);
            NotifyOfPropertyChange(() => Cities);
        }
    }
    public List<string> Countries
    {
        get { return countries; }
        set
        {
            countries = value;
            NotifyOfPropertyChange(() => Countries);
            NotifyOfPropertyChange(() => Cities);
        }
    }
    public List<string> Cities
    {
        get
        {
            switch (company.country)
            {
                case "USA": return new List<string> { "New York", "Los Angeles" };
                case "Germany": return new List<string> { "Hamburg", "Berlin" };
                default: return new List<string> { "DEFAULT", "DEFAULT" };

            }
        }
    }
}

有关如何实现这种级联的完整示例和更多信息，请参阅以下博客文章 ComboBoxes : https://blog.magnusmontin.net/2013/06/17/cascading-comboboxes-in-wpf-using-mvvm/