localization - ASP.NET MVC Model Binder with Global Number Formats

Question

The default model binder is returning errors for properties that are of type double when my application is being used in countries that use different number formatting for decimals (e.g. 1.2 = 1,2). The culture of the site is set conditionally in my BaseController.

I have tried adding a custom model binder and overriding the bindModel function but I can't see how to get around the error in there as the Culture has already been set back to the default of en-GB.

So I tried adding an action filter to my BaseController that sets the Culture there but unfortunately bindModel seems to get fired before my action filter.

How can I get around this? Either by getting the Culture to not reset itself or set it back before bindModel kicks in?

Controller where model comes in invalid:

public ActionResult Save(MyModel myModel)
{
    if (ModelState.IsValid)
    {
        // Save my model
    }
    else
    {
       // Raise error
    }
}

Filter where Culture is set:

public override void OnActionExecuting(ActionExecutingContext filterContext)
{
    CultureInfo culture = createCulture(filterContext);

    if (culture != null)
    {
         Thread.CurrentThread.CurrentCulture = culture;
         Thread.CurrentThread.CurrentUICulture = culture;
    }

    base.OnActionExecuting(filterContext);
}

Custom Model Binder:

public class InternationalDoubleModelBinder : DefaultModelBinder
{
   public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
   {
       ValueProviderResult valueResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
       if (valueResult != null)
       {
           if (bindingContext.ModelType == typeof(double) || bindingContext.ModelType == typeof(Nullable<double>))
           {
               double doubleAttempt;

               doubleAttempt = Convert.ToDouble(valueResult.AttemptedValue);

               return doubleAttempt;
           }
        }
        return null;
   }
}

Answer 1

You want your application to use a single culture, right? If so, you can do this with the globalization tag of your web.config.

<configuration>
    <system.web>
        <globalization
           enableClientBasedCulture="true"        
           culture="en-GB"
           uiCulture="en-GB"/>
    </system.web>
</configuration>

And then you can forget those custom model binder and use the default.

UPDATE: Ok, it's a multi-language application. How do you get the culture you want? Can you call createCulture on the MvcApplication class? You could do this:

public class MvcApplication : HttpApplication
{
    //...
    public void Application_OnBeginRequest(object sender, EventArgs e)
    {
        CultureInfo culture = GetCulture();
        Thread.CurrentThread.CurrentCulture = culture;
        Thread.CurrentThread.CurrentUICulture = culture;
    }
    //...
}

This method is called before the model bind, so, again, you won't need the custom model binder. I hope it works for you :)