Set Culture in an ASP.Net MVC app

Question

What is the best place to set the Culture/UI Culture in an ASP.net MVC app

Currently I have a CultureController class which looks like this:

public class CultureController : Controller
{
    public ActionResult SetSpanishCulture()
    {
        HttpContext.Session["culture"] = "es-ES";
        return RedirectToAction("Index", "Home");
    }

    public ActionResult SetFrenchCulture()
    {
        HttpContext.Session["culture"] = "fr-FR";
        return RedirectToAction("Index", "Home");
    }
}

and a hyperlink for each language on the homepage with a link such as this:

<li><%= Html.ActionLink("French", "SetFrenchCulture", "Culture")%></li>
<li><%= Html.ActionLink("Spanish", "SetSpanishCulture", "Culture")%></li>

which works fine but I am thinking there is a more appropriate way to do this.

I am reading the Culture using the following ActionFilter http://www.iansuttle.com/blog/post/ASPNET-MVC-Action-Filter-for-Localized-Sites.aspx. I am a bit of an MVC noob so am not confident I am setting this in the correct place. I don't want to do it at the web.config level, it has to be based on a user's choice. I also don't want to check their http-headers to get the culture from their browser settings.

Edit:

Just to be clear - I am not trying to decide whether to use session or not. I am happy with that bit. What I am trying to work out is if it is best to do this in a Culture controller that has an action method for each Culture to be set, or is there is a better place in the MVC pipeline to do this?

Answer 1

protected void Application_AcquireRequestState(object sender, EventArgs e)
        {
            if(Context.Session!= null)
            Thread.CurrentThread.CurrentCulture =
                    Thread.CurrentThread.CurrentUICulture = (Context.Session["culture"] ?? (Context.Session["culture"] = new CultureInfo("pt-BR"))) as CultureInfo;
        }

Answer 2

If using Subdomains, for example like "pt.mydomain.com" to set portuguese for example, using Application_AcquireRequestState won't work, because it's not called on subsequent cache requests.

To solve this, I suggest an implementation like this:

1. Add the VaryByCustom parameter to the OutPutCache like this:

   [OutputCache(Duration = 10000, VaryByCustom = "lang")]
   public ActionResult Contact()
   {
       return View("Contact");
   }
   

2. In global.asax.cs, get the culture from the host using a function call:

   protected void Application_AcquireRequestState(object sender, EventArgs e)
   {
       System.Threading.Thread.CurrentThread.CurrentUICulture = GetCultureFromHost();
   }
   

3. Add the GetCultureFromHost function to global.asax.cs:

   private CultureInfo GetCultureFromHost()
   {
       CultureInfo ci = new CultureInfo("en-US"); // en-US
       string host = Request.Url.Host.ToLower();
       if (host.Equals("mydomain.com"))
       {
           ci = new CultureInfo("en-US");
       }
       else if (host.StartsWith("pt."))
       {
           ci = new CultureInfo("pt");
       }
       else if (host.StartsWith("de."))
       {
           ci = new CultureInfo("de");
       }
       else if (host.StartsWith("da."))
       {
           ci = new CultureInfo("da");
       }
   
       return ci;
   }
   

4. And finally override the GetVaryByCustomString(...) to also use this function:

   public override string GetVaryByCustomString(HttpContext context, string value)
   {
       if (value.ToLower() == "lang")
       {
           CultureInfo ci = GetCultureFromHost();
           return ci.Name;
       }
       return base.GetVaryByCustomString(context, value);
   }
   

The function Application_AcquireRequestState is called on non-cached calls, which allows the content to get generated and cached. GetVaryByCustomString is called on cached calls to check if the content is available in cache, and in this case we examine the incoming host domain value, again, instead of relying on just the current culture info, which could have changed for the new request (because we are using subdomains).