从其他窗口刷新组合框列表，MVVM

我正在开发一些应用程序，但遇到一个问题。 我有两个窗口（预订 - 父母和客人 - 儿童）。在父窗口中，我有一个包含客人列表的组合框和一个用于添加新客人的按钮。当我单击该按钮时，“客人”窗口（子窗口）打开。在子窗口中，我将新来宾添加到数据库中，效果很好。 我的问题是：在子窗口中添加新来宾后，如何刷新/更新父窗口中的组合框列表？我知道属性的更改应该反映在视图中，而不需要从数据库检索数据（感谢绑定）。

预订.xaml

    <ComboBox ItemsSource="{Binding Path=Guests}" SelectedItem="{Binding Path=Guest}" Height="25" HorizontalAlignment="Left" IsEditable="True" IsTextSearchEnabled="True" Margin="119,10,0,0" Name="cbGuest" Padding="3,1,1,1"  TextSearch.TextPath="Name" VerticalAlignment="Top" VerticalContentAlignment="Center" Width="141" FontFamily="Times New Roman" FontWeight="Bold" FontSize="14">
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <TextBlock DataContext="{Binding}" Text="{MultiBinding StringFormat='\{0\} ', Bindings={Binding Path=Name}}" />
            </DataTemplate>
        </ComboBox.ItemTemplate>
    </ComboBox>
    <Button BorderBrush="Black" Command="{Binding Path=btnAddGuest}" Content="Novi Gost" FontFamily="Times New Roman" FontWeight="Bold" Height="25" HorizontalAlignment="Left" IsDefault="True" Margin="266,10,0,0" Name="btnNewGuest" VerticalAlignment="Top" Width="62" />

BookingsViewModel.cs

    private tblGuest guest;
    public tblGuest Guest    // Selected guest from combo box
    {
        get
        {
            return guest;
        }
        set
        {
            guest = value;
            OnPropertyChanged("Guest");
        }
    }

    private ObservableCollection<tblGuest> guests;
    public ObservableCollection<tblGuest> Guests    // Guests list in the combo box
    {
        get
        {
            return guests;
        }
        set
        {
            guests = value;
            OnPropertyChanged("Guests");
        }
    }

    public ICommand _btnAddGuest;
    public ICommand btnAddGuest    // Command for opening child window
    {
        get
        {
            if (_btnAddGuest == null)
            {
                _btnAddGuest = new DelegateCommand(delegate()
                {
                    try
                    {
                        Guests guest = new Guests();
                        guest.ShowDialog();
                    }
                    catch
                    {
                        Trace.WriteLine("working...", "MyApp");
                    }
                });
            }
            return _btnAddGuest;
        }
    }

客人.xaml

    <Button Command="{Binding Path= btnAddGuest}" Content="Dodaj" FontFamily="Times New Roman" FontWeight="Bold" Height="36" HorizontalAlignment="Left" Margin="12,402,0,0" Name="btnAddGuest" VerticalAlignment="Top" Width="62" IsDefault="True" />

此按钮（在 Guest.xaml 窗口中）将新来宾添加到数据库中。

GuestViewModel.cs

    private tblGuest guest;
    public tblGuest Guest    // Guest to be added into database
    {
        get 
        {
            return guest;
        }
        set 
        {
            guest = value;
            OnPropertyChanged("Guest");
        }
    }

    public ICommand _btnAddGuest;
    public ICommand btnAddGuest    // Command for adding new guest
    {
        get
        {
            if (_btnAddGuest == null)
            {
                _btnAddGuest = new DelegateCommand(delegate()
                {
                    try
                    {
                        Service1Client wcf = new Service1Client();                           
                        wcf.AddGuest(Guest);    // "AddGuest()" WCF method adds new guest to database
                        wcf.Close();
                    }
                    catch
                    {
                        Trace.WriteLine("working...", "MyApp");
                    }
                });
            }
            return _btnAddGuest;
        }
    }

如何解决这个问题呢？有什么简单的办法吗？您能否详细解释一下您的解决方案，因为我是 WPF、WCF 和 MVVM 的新手......

此致， 弗拉基米尔

Hold BookingsViewModel实例在GuestViewModel上课和通话BookingsViewModel.OnPropertyChanged("Guest")添加新访客时（之后wcf.AddGuest(Guest); line).