On following line from controller
@user = create_from(provider)
Getting exception
#<NoMethodError: undefined method `transaction' for User:Class>
Here is the first line of exception backtrace
"/Users/Gull/.rvm/gems/ruby-2.1.0-preview2/gems/sorcery-0.8.4/lib/sorcery/controller/submodules/external.rb:173:in `create_from'"
This make sense that transaction are not supported by mongo, but is the configuration part that is invoking the transaction part of sorcery ?
adding following line in the model file ... make it working