MVC 5 How to define Owin LoginPath with localized routes

To enhance @martinoss answer, you may reach the same result without implementing a wrapper. Just copy the original handler, assign a new one that implements your redirection logic to modify context.RedirectionUri, and at the end call the original handler.

CookieAuthenticationProvider provider = new CookieAuthenticationProvider();

var originalHandler = provider.OnApplyRedirect;
provider.OnApplyRedirect = context =>
{
    //insert your logic here to generate the redirection URI
    string NewURI = "....";
    //Overwrite the redirection uri
    context.RedirectUri = NewURI;
    originalHandler.Invoke(context);
};

app.UseCookieAuthentication(new CookieAuthenticationOptions
{
   AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
   LoginPath = new PathString(url.Action("Login", "Account")),
   Provider = provider
});

Without taking too much of responsibility on the url format etc, you can do something like the following

public static void Configuration(IAppBuilder app)
{
    UrlHelper url = new UrlHelper(HttpContext.Current.Request.RequestContext);
    app.UseCookieAuthentication(new CookieAuthenticationOptions
    {
        AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
        LoginPath = new PathString(url.Action("LogOn", "Account", new { area = "Account" })),
        Provider = new CookieAuthenticationProvider
        {
            OnApplyRedirect = context => context.Response.Redirect(context.RedirectUri.Replace(CultureHelper.GetDefaultCulture(), Thread.CurrentUiCulture.Name))
        }
    });
}

I exactly had the same problem and figured out a way to overcome this limitation.

In the CookieAuthenticationOptions options, there is a "Provider" property which is initialized with the CookieAuthenticationProvider. This implements a method called ApplyRedirect and a delegate OnApplyRedirect. My first idea was to overwrite this ApplyRedirect and implement the required logic to handle localized routes. But unfortunately it can't be overriden. Passing my logic to OnApplyRedirect causes to overwrite the default behavior. You theoretically can grab the source of this behavior, copy it into your project and modify it to your needs, but this is obviously not a good practice. First, I decided to make a wrapper around the CookieAuthenticationProvider with two extension points using delegates and preserving the default behavior except of the url that is used - or easier, work around the wrapper (thx to lafi).

Then in the auth configuration I added my custom logic to the provider:

public void ConfigureAuth(IAppBuilder app)
{
    UrlHelper url = new UrlHelper(HttpContext.Current.Request.RequestContext);

    CookieAuthenticationProvider provider = new CookieAuthenticationProvider();

    var originalHandler = provider.OnApplyRedirect;

    //Our logic to dynamically modify the path (maybe needs some fine tuning)
    provider.OnApplyRedirect = context =>
    {
        var mvcContext = new HttpContextWrapper(HttpContext.Current);
        var routeData = RouteTable.Routes.GetRouteData(mvcContext);

        //Get the current language  
        RouteValueDictionary routeValues = new RouteValueDictionary();
        routeValues.Add("lang", routeData.Values["lang"]);

        //Reuse the RetrunUrl
        Uri uri = new Uri(context.RedirectUri);
        string returnUrl = HttpUtility.ParseQueryString(uri.Query)[context.Options.ReturnUrlParameter];
        routeValues.Add(context.Options.ReturnUrlParameter, returnUrl);

        //Overwrite the redirection uri
        context.RedirectUri = url.Action("login", "account", routeValues);
        originalHandler.Invoke(context);
    };

    app.UseCookieAuthentication(new CookieAuthenticationOptions
    {
        AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
        LoginPath = new PathString(url.Action("login", "account")),
        //Set the Provider
        Provider = provider
    });
}

See also this code:

• CookieAuthenticationHandler
• CookieAuthenticationProvider

Hope it fits your needs.

UPDATE: For less confusion, I updated my answer to use @Lafis enhancement, not using a wrapper class to apply the extended behavior. Please also give credit to @Lafis when upvoting.

How about this:

var cao = new CookieAuthenticationOptions
        {
            AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie,
            LoginPath = new PathString("/Account/Login"),
            Provider = new CookieAuthenticationProvider { OnApplyRedirect = ApplyRedirect }
        };
app.UseCookieAuthentication(cao);

and

  private static void ApplyRedirect(CookieApplyRedirectContext context)
    {

        UrlHelper _url = new UrlHelper(HttpContext.Current.Request.RequestContext);
        String actionUri = _url.Action("Login", "Account", new { });
        context.Response.Redirect(actionUri);
    }