ASP.NET MVC 5 Internationalization-2

Determining Culture

There is a header field called "Accept-Language" that the browser sends on every request. This field contains a list of culture names (language-country) that the user has configured in their browser. The problem is that this culture may not reflect the real user's preferred language, such as a computer in a public place. We should allow the user to choose a language explicitly and allow them even to change it. In order to do this sort of things, we need to store the user's preferred language in a store, which can be perfectly a cookie. We will create a base controller that inspects the cookie contents first, if there is no cookie, we will use the "Accept-Language" field sent by their browser. Create a controller and name it "BaseController" like below:

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public class BaseController : Controller {     protected override IAsyncResult BeginExecuteCore(AsyncCallback callback, object state)     {         string cultureName = null;                   // Attempt to read the culture cookie from Request         HttpCookie cultureCookie = Request.Cookies["_culture"];         if (cultureCookie != null)             cultureName = cultureCookie.Value;         else             cultureName = Request.UserLanguages != null && Request.UserLanguages.Length > 0 ?                     Request.UserLanguages[0] :  // obtain it from HTTP header AcceptLanguages                     null;         // Validate culture name         cultureName = CultureHelper.GetImplementedCulture(cultureName); // This is safe                   // Modify current thread's cultures                    Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo(cultureName);         Thread.CurrentThread.CurrentUICulture = Thread.CurrentThread.CurrentCulture;                   return base.BeginExecuteCore(callback, state);     } }

Make sure all controllers in this project inherit from this BaseController. The base controller checks if the cookie exists, and sets the current thread cultures to that cookie value. Of course, because cookie content can be manipulated on the client side, we should always validate its value using a helper class called "CultureHelper". If the culture name is not valid, the helper class returns the default culture.