WPF Master/Detail data binding between 2 combobox

Question

I have two combobox where Parent has to show the list of Countries and the child combo has to show a list of cities of the choosen country. The data is stored in a Diction

Answer 1

For the parent ComboBox, bind the SelectedItem to a property on your model:

Where SomePropertyOnModel is of the same type as an Item in the Countries List.

For the child ComboBox, everything should be the same:

Side Note: You'll notice that I specifically added the ItemsSource binding to both the ComboBoxes.

In the model, whenever the SomePropertyOnModel is set, update the CountriesCitiesList based on the value received, i.e.,:

private string _somePropertyOnModel;
public string SomePropertyOnModel 
{
    get { return _somePropertyOnModel; }
    set 
    {
        _somePropertyOnModel = value;
        // call NotifyPropertyChanged
        UpdateCountriesCitiesList();
    }
}

private void UpdateCountriesCitiesList()
{
    // set CountriesCitiesList based on the 
    // SomePropertyOnModel value
    // CountriesCitiesList should be an ObservableCollection and the values
    // should be cleared and then added.
    CountriesCitiesList.Clear();
    CountriesCitiesList.Add( "Springfield" );
}