ASP.Net MVC: Internationalization (i18n) and Localization (i10n) in MVC

Internationalization (i18n) and Localization (i10n) are collectively know as Globalization.

ASP.Net Culture

Every executing .Net thread has two important properties.

1. Thread.Culture
2. Thread.CurrentUICulture

Thread.Culture

Impacts formatting of dates and numbers. For example:
DateTime.Now.ToString();  // how is date displayed, month first, day first, etc.
date.ToShortDateString();   // format date appropriate for the culture
 //  what currency symbol is shows; what is 1000s separator
//  decimal separator; 10.00 E (in euros)
amount.ToString(“c”);

Thread.CurrentUICulture

• Impacts loading of resources, such as strings
• Use Resources.resx to Localize the strings being displayed. For example, Strings.resx will store default resources.
• Resx files can store localized text and binary assets
• Create a Resource for each language you wish to support. For example, String.es.resx will store resource for Spanish culture
• Resource Loader loads the current resources for the culture
• In Visual Studio, set the BuildAction to embedded resource
• Visual Studio generates strongly-typed classes for Resource access
• Resources.Greeting returns culture specific string; falls back to base resources if no culture specific resource is present

Setting Culture in ASP.NET using HTTP headers

• Default language of the browser is passed in the accept-language header
• To turn on, refer to the <globalization> section of web.config

<system.web>

  <globalization culture=”auto” uiCulture=”auto” />

</system.web>

Testing formatting based on accept-language header

• Go to Settings for Internet Explorer
• Internet Options
• Under appearance press [Languages]
• Pick a language

Manually Setting Culture in ASP.NET

• For example, user can select the language on the log in page
• Use CultureInfo::DefaultThreadCurrentCulture to set desired culture before using formatting classes and methods

Referencing resources in MVC 

In Data Model using Data Annotation

[Required(ErrorMessageResourceType=type(<namespace>.MyResources),
ErrorMessageResourceName=”UserNameRequiredError”]
public string username {get; set;}

In Razor View

1. Create Resource files. The resource files can be created in the same Web project, a Separate Library, or a separte folder in the Web project.

2. Create MyResources.resx
Greeting: Welcome

3. Change access modifier to public from Internal so that the Razor views can use it since Razor views are compiled to a different assembly.

4. Add MyResources.fr.resx
Greeting: Bonjour!
For the localized resource, no code generation. Only done for the base resource file.

5. Modify view to use the resources

<h1>@<namespace>.MyResources.Greeting</h2>

This will load the correct string based on appropriate language accept header.

We can also create resources within the View subfolder and use in the View.

In Cached controller action 

// Returns language-specific CACHED data
// Adjust cache settings to vary by language
[OutputCache  ... VarByHeader=”Accept-Language”)]

Controller

Can also use as follows in controller
ViewBag.Message = MyResources.Greeting;