ASP.NET MVC: When to set Thread.CurrentThread.CurrentUICulture?

Request.UserLanguages[0] can only be a hint what language the users wishes to see. Most users dont know where to change the browser language.

Another point: Dont be sure that Request.UserLanguages[0] is a valid language. It can even be null. (Not sure what bots have there)

You usually have a Language chooser on the page. Once a user has selected a language there, it is stored in a cookie, session or url. I like to use url because I think it looks pretty.

If a user sees your page without having set a language on your page, you should check if Request.UserLanguages[0] is a language you support and set Thread.CurrentThread.CurrentUICulture.

I use a filter to set Thread.CurrentThread.CurrentUICulture. Thats ok as long as no other filter is using Thread.CurrentThread.CurrentUICulture. Otherwise you would need to set the right execution order for filters.

I also use Matts helper and it worked very well so far.

Here is a sample using an HttpModule:

http://weblogs.manas.com.ar/smedina/2008/12/17/internationalization-in-aspnet-mvc/

Other options, create a base Controller class and implement the localization logic there. Or use an action filter attribute, but you'll have to remember to add it on every controller or combine this approach with the base Controller class.