browser - ASP.NET MVC 4 Mobile Display Modes Stop Working

Question

Mobile display modes in ASP.NET MVC 4 stop serving the correct views after about an hour of uptime, despite browser overrides correctly detecting an overridden mobile device.

Recycling the application pool temporarily solves the problem.

The new browser override feature correctly allows mobile devices to view the desktop version of a site, and vice-versa. But after about an hour of uptime, the mobile views are no longer rendered for a mobile device; only the default desktop Razor templates are rendered. The only fix is to recycle the application pool.

Strangely, the browser override cookie continues to function. A master _Layout.cshtml template correctly shows "mobile" or "desktop" text depending on the value of ViewContext.HttpContext.GetOverriddenBrowser().IsMobileDevice, but the wrong views are still being rendered. This leads me to believe the problem lies with the DisplayModes.

The action in question is not being cached:

[OutputCache(NoStore = true, Duration = 0, VaryByParam = "*")]

I am using 51Degrees for mobile detection, but I don't think this should affect the overridden mobile detection. Is this a bug in DisplayModes feature for ASP.NET MVC 4 Beta & Developer Preview, or am I doing something else wrong?

---

Here is my DisplayModes setup in Application_Start:

DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("iPhone")
{
    ContextCondition = context =>
        context.GetOverriddenBrowser().IsMobileDevice
        && (context.Request.UserAgent.IndexOf("iPhone", StringComparison.OrdinalIgnoreCase) >= 0
        || context.Request.UserAgent.IndexOf("Android", StringComparison.OrdinalIgnoreCase) >= 0
        || !context.Request.Browser.IsMobileDevice)
    });

/*  Looks complicated, but renders Home.iPhone.cshtml if the overriding browser is
    mobile or if the "real" browser is on an iPhone or Android. This falls through
    to the next instance Home.Mobile.cshtml for more basic phones like BlackBerry.
*/

DisplayModeProvider.Instance.Modes.Insert(1, new DefaultDisplayMode("Mobile")
{
    ContextCondition = context =>
        context.GetOverriddenBrowser().IsMobileDevice
});

Answer 1

This is a known issue in MVC 4 (Codeplex: #280: Multiple DisplayModes - Caching error, will show wrong View). This will be fixed in the next version of MVC.

In the meantime you can install a workaround package available here: http://nuget.org/packages/Microsoft.AspNet.Mvc.FixedDisplayModes.

For most applications simply installing this package should resolve the issue.

For some applications that customize the collection of registered view engines, you should make sure that you reference Microsoft.Web.Mvc.FixedRazorViewEngine or Microsoft.Web.Mvc.FixedWebFormViewEngine, instead of the default view engine implementations.