Rails: Why am I getting uninitialized Constant for a rake task, Rails 4.1.8

I'm not sure why either works, but if this is rails and those are rails models, your tasks should depend on the environment:

task :get_roles => [ :environment ] do

By depending on the :environment task, it first loads rails.

see also:

What's the 'environment' task in Rake?

You can also run rake task as

bundle exec rake environment xaaron:get_role

this will load Rails environment first.