MVC4 Beta: Important Change to DisplayMode

As many of you know the beta of MVC4 came out. Of course I downloaded and installed it.

I noticed my existing code such as…

DisplayModes.Modes.Insert(0, new DefaultDisplayMode("iPhone")
ContextCondition = (ctx => ctx.Request.UserAgent.IndexOf(
"iPhone", StringComparison.OrdinalIgnoreCase) >= 0)

gave an error “DisplayModes” does not exist in the current context. Wait a sec, I updated my references and everything, what gives.

well they threw something new in there.

the correct code is now..

DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("iPhone")
ContextCondition = (ctx => ctx.Request.UserAgent.IndexOf(
"iPhone", StringComparison.OrdinalIgnoreCase) >= 0)

Notice the


it replaced the older DisplayModes.

I am sure there is more. I will post them as I find them.

MVC4 : Mobile Routing : Part 2

Updated 12 March 2012 to support the MVC4 Beta

In part one of this series I showed a brief intro into the view routing capabilities of MVC4. In this article we are going to dig a bit deeper and explore how it can be extended.

While just havingthe ability to redirect to a mobile view is neat, it would be even better to be able to add more conditions and view types than just the existing mobile one.

Fortunately the framework does have this ability.

To create new view versions (DefaultDisplayModes), you add each DefaultDisplayMode in the Application_Start event of the global.asax.cs.  The running application will the select which view to use based on declared conditions being met.

Here is an example of an a DefaultDisplayMode being added to the DisplayModes list

DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("iPhone")
ContextCondition = (ctx => ctx.Request.UserAgent.IndexOf(
"iPhone", StringComparison.OrdinalIgnoreCase) >= 0)

DisplayModeProvider.Instance is an IList and Modes.Insert is a standard insert with an index and item to be inserted.

The concise format is;

DisplayModeProvider.Instance.Modes.Insert({index}, new DefaultDisplayMode("{DisplayModeName}") {Context})

{Context} is evaluated at runtime and must return a Boolean, If a true is returned then the View Engine attempts to load a view with that Display mode name.


The viewengine starts with the very first displaymode in the Displaymodes<IList>  which is at index 0 and iterates through the  Displaymodes<IList>  until a matching view is found.

So given these inserts in this order in code (no context to keep it simple)

DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("Mobile")
DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("Tablet")
DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("AndroidTablet")

The veiwengine would evaluate for AndroidTablet if that fails go to Tablet, then evaluate for mobile.

There already is a default DefaultDisplayMode(“Mobile”) already baked into the framework. Adding another DefaultDiplayMode named mobile does not erase that display mode it just adds another conditional to direct the view engine to use


Complex Conditionals

Remember that the evaluation must return a Boolean ? Well that lets you create fairly complex conditions such as this one below.

<p>DisplayModeProvider.Instance.Modes.Insert(0, new DefaultDisplayMode("Mobile")
ContextCondition = (ctx =>
ctx.Request.UserAgent.IndexOf("iPad", StringComparison.OrdinalIgnoreCase) >= 0 ||
ctx.Request.UserAgent.IndexOf("android", StringComparison.OrdinalIgnoreCase) >= 0 ||
ctx.Request.UserAgent.IndexOf("iPhone", StringComparison.OrdinalIgnoreCase) >= 0 ||
ctx.Request.UserAgent.IndexOf("Windows Phone OS",StringComparison.OrdinalIgnoreCase)>= 0

Here the condition is checking for a variety of user agent strings using the OR (||) operator.

To see how far some have taken this, I highly recomend reading Eric Sowell’s blog at


We really cant wait till this becomes RTM. No really we can’t, we are running on the developer’s preview of MVC 4.

I do hope this has helped some of you out there. I promise I will add more as I get time. Wish me luck.

RDU Code Camp 2011

I will be presenting at this years Code Camp in Raleigh-Durham NC.  I will be showing off the Microsoft MVC 4 Developers Preview. Showing off the new conditional routing features of the framework (Mobile, baby), and a little bit of JQuery mobile just for fun.

So Can you guess what this is ?

DisplayModes.Modes.Insert({index}, new DefaultDisplayMode("{DisplayModeName}")  { {Context}  }

Check out See you there

MVC 4 :Mobile Routing: Part One

If you have not read Scott Hanselman’s Blog Post  on the developers preview of Visual Studio 2011, Asp.Net and MVC 4. GO READ IT !!

What caught my eye about MVC 4 was its new mobile support.   As mentioned in Scott’s Blog;

ASP.NET MVC 4 Developer Preview is the latest release of our MVC framework. This release includes built-in support for mobile sites, new, fresh HTML5 project templates as well as jQuery Mobile. It has enhanced support for asynchronous methods, and custom code generation.

You can download the bits from here

So one of the new is mobile device detection and routing.  In normal MVC you have a controller action that has an associated SINGLE view. The view then has the same filename as the action method. MVC 4 has a feature that allows routing from a  {controller}/{action} to one of several views depending on whether or not the browsing device is mobile.

The MVC 4 Functionality simply adds the identifier mobile between the two names {ActionName}.mobile.{fileType} example “” This can be used in the case of _layout pages as well. If a mobile device browses to the site then a view with the .mobile middle name will be returned if it it exists. If not then the desktop view will be returned.