c# - 可以级联两个ComboBox，需要级联第三个ComboBox

Question

我需要使用数据绑定(bind)创建 3 个级联组合框(A、B 和 C)。从我看到的示例中，我能够获得两个工作(A 和 B)，但我不确定如何连接 ComboBox C，其 ItemsSource 应该取决于 ComboBox B 中所做的选择。所以，就像有对于组合框 A 中显示的每个类别，在组合框 B 中显示一组原因，我需要在组合框 C 中为组合框 B 中显示的每个原因显示一组子原因。随着选择的变化，基础下拉列表值也会发生变化。我希望这是有道理的。有没有办法绑定(bind)到 ViewModel 属性来实现这个或???。

XAML

     <ComboBox x:Name="cbxA"
                ItemsSource="{Binding ProjectCategoryList}" 
                SelectedIndex="{Binding Path=SelectedProject.Category}"                      
                DisplayMemberPath="Category"/>
     <ComboBox x:Name="cbxB"
                ItemsSource="{Binding ElementName=cbxA, Path=SelectedItem.Reasons}" 
                Text="{Binding Path=SelectedProject.Reason}" DisplayMemberPath="Name"/>
     <ComboBox x:Name="cbxC"
                ItemsSource="{Binding ElementName=cbxB, Path=SelectedItem.SubReasons}" 
                Text="{Binding Path=SelectedProject.SubReason}"/>

ViewModel

    private Project selectedProject;

    public Project SelectedProject
    {
        get { return selectedProject; }
        set
        {
            if(selectedProject != value)
            {
                selectedProject = value;
                NotifyPropertyChanged("SelectedProject");
            }
        }
    }

    public List<ProjectCategory> ProjectCategoryList
    {
        get
        {
            return new List<ProjectCategory>()
            {
                new ProjectCategory
                {
                    Category = "One",
                    Reasons = new List<Reason>
                    {
                        new Reason() { Name = "A", SubReasons = new List<String> { "1", "2", "3" }},
                        new Reason() { Name = "B", SubReasons = new List<String> { "4", "5", "6" }},
                        new Reason() { Name = "C", SubReasons = new List<String> { "7", "8", "9" }}, 

                    }
                },
                new ProjectCategory
                {
                    Category = "Two",
                    Reasons = new List<Reason>
                    {
                        new Reason() { Name = "D", SubReasons = Enumerable.Empty<string>()},
                        new Reason() { Name = "E", SubReasons = Enumerable.Empty<string>()},
                        new Reason() { Name = "F", SubReasons = Enumerable.Empty<string>()},
                    }
                },
                new ProjectCategory
                {
                    Category = "Three",
                    Reasons = new List<Reason>
                    {
                        new Reason() { Name = "J", SubReasons = Enumerable.Empty<string>()},
                        new Reason() { Name = "K", SubReasons = Enumerable.Empty<string>()},
                    }
                },
            };
        }
    }

ProjectCategory.cs

public class ProjectCategory
{
    public string Category { get; set; }
    public IEnumerable<Reason> Reasons { get; set; }
}

public class Reason
{
    public string Name { get; set; }
    public IEnumerable<string> SubReasons { get; set; }
}

Answer 1

Reasons ProjectCategory 的属性(property)类应返回 IEnumerable<Reason>而不是 IEnumerable<string>和 Reason类应包含 Name (或 Reason )类型的属性 string和 IEnumerable<string>子原因。

然后可以绑定(bind)cbxC一样的方法:

 <ComboBox x:Name="cbxA"
            ItemsSource="{Binding ProjectCategoryList}" 
            SelectedIndex="{Binding Path=SelectedProject.Category}"                      
            DisplayMemberPath="Category"/>
 <ComboBox x:Name="cbxB"
            ItemsSource="{Binding ElementName=cbxA, Path=SelectedItem.Reasons}" 
            DisplayMemberPath="Name" />
 <ComboBox x:Name="cbxC"
      ItemsSource="{Binding ElementName=cbxb, Path=SelectedItem.SubReasons}" />

public class ProjectCategory
{
    public string Category { get; set; }
    public IEnumerable<Reason> Reasons { get; set; }
}

public class Reason
{
    public string Name { get; set; }
    public IEnumerable<string> SubReasons { get; set; }
}