Our First API Discussion

When should I use rails new my_app --api ? or it's ok to use rails new as usual even if I'm building an API

I´m getting a undefined method `temp' for nil:NilClass when i try to access json.temp @location.recordings.last.temp, I'm confused why this would be as i have the has_many set here is my code if anyone has any input that would be great git code here https://github.com/jrwrest/weather-app

Note: if rake routes doesn't work for you, it is because it has migrated to "rails routes".