Throw a better exception when the user didn't add the MVC services

[danroth27]

Currently you get an ArgumentNullException when you use MVC, but didn't add the MVC services. We should throw a better exception.

[yishaigalatzer]

@dougbu - Here is the first replacement for enum support for this sprint

[rynowak]

@davidfowl Had an earlier suggestion to auto-fix this problem for the user rather than throwing here. #128 #Demoware

[yishaigalatzer]

We decided to throw and not autofix

-----Original Message-----
From: Ryan Nowak
Sent: 4/30/2014 11:34 AM
To: aspnet/WebFx
Cc: Yishai Galatzer
Subject: Re: [WebFx] Throw a better exception when the user didn't add the MVCservices (#347)

@davidfowl Had an earlier suggestion to auto-fix this problem for the user rather than throwing here. #128 #Demoware

—
Reply to this email directly or view it on GitHub.

[dougbu]

Message already seems pretty good. Certainly not throwing an NRE now. Is this issue still relevant?

FYI message from Autofac, when using .NET 4.5:

The requested service 'Microsoft.AspNet.Mvc.IActionDescriptorsCollectionProvider' has not been
registered. To avoid this exception, either register a component to provide the service, check
for service registration using IsRegistered(), or use the ResolveOptional() method to resolve an
optional dependency.

and from the default ServiceProvider, when using K10:

TODO: No service for type 'Microsoft.AspNet.Mvc.IActionDescriptorsCollectionProvider' has been
registered. 

[rynowak]

@dougbu this still isn't good enough. It doesn't tell the user what to do to fix the problem.

Did you call UseServices()? Did you call AddMvc()? Did you call .UseMvc()? you should do that.

[dougbu]

My question was really about balancing that usability improvement (which seems slight) against breaking the preferred DI model and explicitly calling serviceProvider.GetService<IActionDescriptorsCollectionProvider>() from the DefaultActionSelector constructor.

[yishaigalatzer]

Same as #543

[sornaks]

Checked in. 791518d