Xamarin Binding to control with Converter - xamarin

Question

I am trying to create a text box (Editor) where as the person types in it, it decrements a number of characters remaining and shows, for example: "56 characters remaining" in a Label. I know how to write the Converter , but at the moment the value parameter when the Converter is called is null. The parameter to the Converter is 200 as expected. Even if I remove the Editor Binding and set it's Text="Hello", the value is still null when the Converter is called.
The Label and Editor are defined as follows:
<Label
BindingContext="{x:Reference CommentEditor}"
Text="{Binding Path=Text,
Converter={StaticResource CharactersRemainingConverter}, ConverterParameter=200}"/>
<Editor
x:Name="CommentEditor"
Text="{Binding Comment}"
Placeholder="Comment up to 200 characters"
MaxLength="200">
</Editor>
Can anyone see what is wrong?

Answer 1

you could change like this:
<ContentPage.Resources>
<ResourceDictionary>
<local:CharactersRemainingConverter x:Key="charactersRemainingConverter" />
</ResourceDictionary>
</ContentPage.Resources>
<Label
BindingContext="{x:Reference CommentEditor}"
Text="{Binding Path=Text.Length,
Converter={StaticResource charactersRemainingConverter}, ConverterParameter=200}"/>
<Editor
x:Name="CommentEditor"
Text="{Binding Comment}"
Placeholder="Comment up to 200 characters"
MaxLength="200">
</Editor>
in your CharactersRemainingConverter :
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return string.Format("{0} characters remaining",(int.Parse((string)parameter) - (int)value));
}