Use IMarkupExtension together with StringFormat - xaml

Question

I'm using the TranslateExtension from Xamarin. Is it possible to add a StringFormat to the call?
Currently, I have
<Label Text="{i18n:Translate User}" />
but I would need something like this
<Label Text="{i18n:Translate User, StringFormat='{0}:'}" />
If I do the latter, I get
Xamarin.Forms.Xaml.XamlParseException: Cannot assign property "StringFormat": Property does not exists, or is not assignable, or mismatching type between value and property
I know I could add another translation with a colon, but it would be nice to have a different option.

Answer 1

A bit late to the party, but doing it with the standard extension and just XAML, go like this:
<Label Text="{Binding YourDynamicValue, StringFormat={i18n:Translate KeyInResources}}"/>
Your translation should look something like: Static text {0}. Where {0} is replaced by the value you bind to.
The problem is that the Translate extension just gets your string out of the resources, and doesn't have a StringFormat property etc. But you can assign the retrieved resource value to the StringFormat of the Binding.

Answer 2

You can add a parameter property to TranslateExtension.
My TranslateExtension looks like this. You can take the Parameter parts and add it to the one from the Xamarin sample.
[ContentProperty("Text")]
public class TranslateExtension : IMarkupExtension
{
public string Text { get; set; }
public string Parameter { get; set; }
object IMarkupExtension.ProvideValue(IServiceProvider serviceProvider)
{
try
{
if (Text == null)
return null;
var culture = new CultureInfo(CultureHelper.CurrentIsoLanguage);
var result = LocalizationResources.ResourceManager.GetString(Text, culture);
if (string.IsNullOrWhiteSpace(Parameter))
{
return string.IsNullOrWhiteSpace(result) ? "__TRANSLATE__" : result;
}
return string.IsNullOrWhiteSpace(result) ? "__TRANSLATE__" : string.Format(result, Parameter);
}
catch (Exception ex)
{
TinyInsights.TrackErrorAsync(ex);
return "__TRANSLATE__";
}
}
}

Answer 3

Here I have updated the Xamarin sample:
[ContentProperty("Text")]
public class TranslateExtension : IMarkupExtension
{
readonly CultureInfo ci = null;
const string ResourceId = "UsingResxLocalization.Resx.AppResources";
static readonly Lazy<ResourceManager> ResMgr = new Lazy<ResourceManager>(() => new ResourceManager(ResourceId, IntrospectionExtensions.GetTypeInfo(typeof(TranslateExtension)).Assembly));
public string Text { get; set; }
public string StringFormat {get;set;}
public TranslateExtension()
{
if (Device.RuntimePlatform == Device.iOS || Device.RuntimePlatform == Device.Android)
{
ci = DependencyService.Get<ILocalize>().GetCurrentCultureInfo();
}
}
public object ProvideValue(IServiceProvider serviceProvider)
{
if (Text == null)
return string.Empty;
var translation = ResMgr.Value.GetString(Text, ci);
if (translation == null)
{
#if DEBUG
throw new ArgumentException(
string.Format("Key '{0}' was not found in resources '{1}' for culture '{2}'.", Text, ResourceId, ci.Name),
"Text");
#else
translation = Text; // HACK: returns the key, which GETS DISPLAYED TO THE USER
#endif
}
if(!string.IsNullOrWhitespace(StringFormat)
return string.Format(StringFormat, translation);
return translation;
}
}