How to bind a combo-box to a collection of multi-language values in WPF?

Question

I am trying to set up a multi-language application, so when the user changes the display language all the texts in all the open windows change automatically. I am having issues through with binding combo-box control. The binding needs to be done in code-behind as I have dynamic content coming from a database, and sometimes I even have to create additional combo-boxes at runtime. Also I do not want to keep the translations in the database because I do not want to query the database every time a user is changing the display language. What I did until now:

in xaml:

<ComboBox x:Name="cmb"/>

and in C#:

    public class MyCmbItem
    {
        public int Index { get; set; }
        public string Text { get; set; }
    }

    private ObservableCollection<MyCmbItem> LoadText() 
    {
        ObservableCollection<MyCmbItem> _result = new ObservableCollection<MyCmbItem>();
        foreach (var _item in _list)
        {
            //the list is coming from a database read
            _result.Add(new MyCmbItem { Index = _item.Value, Text = _res_man_global.GetString(_item.KeyText, _culture) });
        }
        return _result;
    }


    public ObservableCollection<MyCmbItem> MyTexts
    {
        get { return LoadText(); }
        set {} //I do not have to add/remove items at runtime so for now I leave this empty
    }

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        ...
        LoadList(); //this adds values in _list
        cmb.ItemsSource = MyTexts; //this populates the combo-box

Here I got stuck and I do not know how to determine the combo-box to refresh the displayed texts. The method must achieve that if I have several windows opened each containing a random number of combo-boxes, when I change the current language all the combo-boxes in all the windows will refresh the displayed list, without affecting other values inside (like the selected item). Does anybody know how this can be done?

Many thanks.

Answer 1

For your xaml UI, the INotifyPropertyChanged interface indicates updates of the viewmodel. You can extend your class like this:

public class MyCmbItem : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected void NotifyPropertyChanged(string APropertyName)
    {
        var property_changed = PropertyChanged;
        if (property_changed != null)
        {
            property_changed(this, new PropertyChangedEventArgs(APropertyName));
        }
    }  

    private string _Text;
    private string _KeyText;

    public int Index { get; set; }


      public string Text
      {
          get { return _Text;}

          set { 
              if (_Text != value)
              {
                  _Text = value;
                  NotifyPropertyChanged("Text");

              }
          }
      } 

    public MyCmbItem(string key_text, int index)
    {
        Index = index;
        _KeyText = key_text;

        RefreshText();

        _res_man_global.LanguageChanged += () => RefreshText();
    }

    public void RefreshText()
    {
        Text = _res_man_global.GetString(_KeyText, _culture);
    }
}

Your view can simply bind to the Text-property as following:

  <DataTemplate DataType="{x:Type local:MyCmbItem}">
            <TextBlock Text="{Binding Path=Text}"/>
        </DataTemplate>

Note: I assumed that your language class is global and has some kind of language-changed notification event.