如何在UWP中将静态资源字符串传递给ConverterParameter

Question

I m doing an UWP project and I wan't to format a string using a converter and Static resource String because the application is in mulitple languages.

Here is my converter :

public class StringFormatConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, string language)
        {
            if (value == null)
                return null;

            if (parameter == null)
                return value;

            return string.Format((string)parameter, value);
        }

        public object ConvertBack(object value, Type targetType, object parameter,
            string language)
        {
            throw new NotImplementedException();
        }
    }

Here the string in my Resource Strings.Xaml file :

<x:String x:Key="nbItems">You have {0} items...</x:String>

Here the element where I wan't to pass this formatter :

<TextBlock  Text="{x:Bind NbItems, Converter={StaticResource StringFormatConverter}, ConverterParameter={StaticResource nbItems}, Mode=OneWay}"/>

It's not working but if I do like this it works :

  <TextBlock  Text="{x:Bind NbItems, Converter={StaticResource StringFormatConverter}, ConverterParameter='You have {0} items..', Mode=OneWay}"/>

The parameters is always null in my converter, why it's not working ?

Answer 1

Not exactly certain why the parameter is null, however I have come up with a workaround. Move your strings into a Resource file ( see here ).

Then change the parameter you pass to your converter to the String Name, like so:

<TextBlock  Text="{x:Bind NbItems, Converter={StaticResource StringFormatConverter}, ConverterParameter='FORMAT', Mode=OneWay}" />

Finally change your converter to load the the resource using the parameter like so:

public object Convert(object value, Type targetType, object parameter, string language) {
  if (value == null)
    return null;

  var loader = new Windows.ApplicationModel.Resources.ResourceLoader();
  var str = loader.GetString((string)parameter);

  return string.Format(str, value);
}

Hope this helps.