Globalization and localization

Internationalization involves Globalization and Localization.

Globalization is the process of designing apps that support different cultures. Globalization adds support for input, display, and output of a defined set of language scripts that relate to specific geographic areas.

Localization is the process of adapting a globalized app, which you have already processed for localizability, to a particular culture/locale.

Use localization

IStringLocalizer and IStringLocalizer<T> were architected to improve productivity when developing localized apps. IStringLocalizer uses the ResourceManager and ResourceReader to provide culture-specific resources at run time.

public class BookController : Controller
{
    private readonly IHtmlLocalizer<BookController> _localizer;

    public BookController(IHtmlLocalizer<BookController> localizer)
    {
        _localizer = localizer;
    }

    public IActionResult Hello(string name)
    {
        ViewData["Message"] = _localizer["<b>Hello</b><i> {0}</i>", name];

        return View();
    }
}

A French resource file could contain the following:

Key	Value
<i>Hello</i> <b>{0}!</b>	<i>Bonjour</i> <b>{0} !</b>

Note: You generally want to only localize text and not HTML.

Configure localization

Localization is configured in the Startup.ConfigureServices method:

services.AddLocalization(options => options.ResourcesPath = "Resources");

services.AddMvc()
    .AddViewLocalization(LanguageViewLocationExpanderFormat.Suffix)
    .AddDataAnnotationsLocalization();

• AddLocalization Adds the localization services to the services container. The code above also sets the resources path to "Resources".

• AddViewLocalization Adds support for localized view files. In this sample view localization is based on the view file suffix. For example "fr" in the Index.fr.cshtml file.

• AddDataAnnotationsLocalization Adds support for localized DataAnnotations validation messages through IStringLocalizer abstractions.

Localization middleware

The current culture on a request is set in the localization middleware. The localization middleware is enabled in the Startup.Configure method.

var supportedCultures = new[]
{
    new CultureInfo("en-US"),
    new CultureInfo("fr"),
};

app.UseRequestLocalization(new RequestLocalizationOptions
{
    DefaultRequestCulture = new RequestCulture("en-US"),
    // Formatting numbers, dates, etc.
    SupportedCultures = supportedCultures,
    // UI strings that we have localized.
    SupportedUICultures = supportedCultures
});