28 April 2011

Today I spent hours trying to make one line of code work. Fortunately Miguel Castro was ultimately able to help me troubleshoot the issue thanks to his deep understanding of all things ASP.NET.

The line of code seems so simple:

var data = Roles.GetRolesForUser(“rocky”);

In this case Roles is the RoleProvider API from System.Web.Security, and the method returns a string array with the roles for the user.

This line of code works great in my aspx page. No problem at all.

But in the same web project it throws a NullReferenceException when called from a WCF service (in a svc).

No stack trace. No detail. No nothing. I Binged, and Googled, and created a whole new solution (figuring my first solution was somehow corrupted). But nothing helped.

To cut to the answer, this works in a WCF service:

var data = Roles.Provider.GetRolesForUser(“rocky”);

See the difference? Instead of relying on the static helper method on the Roles type, this code explicitly calls the method on the default provider instance.

(fwiw, I think this behavior is relatively new, because that code used to work. I just don’t remember how long ago it was that it worked – .NET 3 or 3.5 – so perhaps something broke in .NET 4?)

In any case, problem solved – thanks Miguel!!