C# 使用实体框架在wpf datagrid中级联组合框

我正在使用实体框架模型使用数据模板列（而不是DataGridComboxColumn）中的组合框。在datagrid的第一列中。组合框应显示国家，在第二列中，组合框应显示国家。当一行中的国家发生更改时，第二列组合中的状态必须根据该行中的国家进行更新。我有三个表，即国家（国家id int、国家名称）、州（国家id、国家id、国家名称）和地区（国家id、国家id、地区id、地区名称）。我有四个.cs文件

1:testEntities.cs

public partial class testEntities : DbContext
{
    public testEntities()
        : base("name=testEntities")
    {
    }
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        throw new UnintentionalCodeFirstException();
    }
    public DbSet<country> countries { get; set; }
    public DbSet<district> districts { get; set; }
    public DbSet<state> states { get; set; }
}

public partial class state
{
    public Nullable<byte> country_id { get; set; }
    public byte state_id { get; set; }
    public string state_name { get; set; }
}

public partial class district
{
    public Nullable<byte> country_id { get; set; }
    public Nullable<byte> state_id { get; set; }
    public byte district_id { get; set; }
    public string district_name { get; set; }
}

3:-state.cs

public partial class testEntities : DbContext
{
    public testEntities()
        : base("name=testEntities")
    {
    }
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        throw new UnintentionalCodeFirstException();
    }
    public DbSet<country> countries { get; set; }
    public DbSet<district> districts { get; set; }
    public DbSet<state> states { get; set; }
}

public partial class state
{
    public Nullable<byte> country_id { get; set; }
    public byte state_id { get; set; }
    public string state_name { get; set; }
}

public partial class district
{
    public Nullable<byte> country_id { get; set; }
    public Nullable<byte> state_id { get; set; }
    public byte district_id { get; set; }
    public string district_name { get; set; }
}

提前非常感谢

这是一个开始

using System.Windows.Data;
private void Window_Loaded(object sender, RoutedEventArgs e)
{           
    testEntities te= new testEntities ();
    CollectionViewSource countryViewSource = ((CollectionViewSource)(this.FindResource("countryViewSource")));
    CollectionViewSource stateViewSource = ((CollectionViewSource)(this.FindResource("stateViewSource")));
    CollectionViewSource districtViewSource = ((CollectionViewSource)(this.FindResource("districtViewSource")));

    te.countries .Load();
    te.states .Load ();
    te.districts .Load ();

    countryViewSource.Source = te.countries.Local;
    stateViewSource.Source = te.states.Local;
    districtViewSource.Source = te.countries.Local;
}

如果州在一个县，那么把它们放在该国

public partial class country
{
    public byte country_id { get; set; }
    public string country_name { get; set; }
    public DbSet<state> states { get; set; }
}

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您好，感谢您回答我的问题，在datagrid中级联cb，但它不工作。我可以知道你的电子邮件，以便我可以发送完整的代码thnaks我的电子邮件nirankar。kaushik@gmail.com