Can I access IIdentity from Web API
Solution 1:
They removed GetUserPrincipal in ASP.NET MVC 4 RC. However it seems the ApiController property User has replaced this: http://msdn.microsoft.com/en-us/library/system.web.http.apicontroller.user
Solution 2:
Yes you can. ApiController has a Request property of type System.Net.Http.HttpRequestMessage; this holds details about the current request naturally (it also has a setter for unit testing purposes). HttpRequestMessage has a Properties dictionary; you will find the value of the key MS_UserPrincipal holds your IPrincipal object.
In researching this answer, I came across the System.Web.Http.HttpRequestMessageExtensions which has a GetUserPrincipal(this HttpRequestMessage request) extension method which accesses this dictionary value; I hadn't seen this extension method before and was accessing Request.Properties["MS_UserPrincipal"] directly, but this might be a better method (less dependent on the ASP.NET Web Api team keeping the name of the key the same...)
Solution 3:
You can try to use this extension method from System.ServiceModel.dll:
public static IPrincipal GetUserPrincipal(this HttpRequestMessage request);
as:
IPrincipal principal = request.GetUserPrincipal();
IIdentity identity = principal.Identity;
Solution 4:
I had the same problem and I found this way.
In your ApiController you can usebase.ControllerContext.RequestContext.Principal.Identity.;