Rails views: .html.haml vs .haml / html.erb vs erb

Normally I use the .haml extension for my views. Today while working on one Rails app I have learned why in some cases one cannot just use .haml.

	class Contacts::ApplicationController
	respond_to :json, :html
	def index
	respond_with Contacts.all
	end
	end

view raw gistfile1.rb hosted with ❤ by GitHub

Given the above controller, if you just use .haml instead of .html.haml every response will be rendered using that .haml template.

Initially I had created app/views/contacts/index.haml for responding to html requests.
After I changed 'repond_to :html' to 'respond_to :html, :json' -- I was confused when I saw an HTML response when fetching '/contacts.json'.

Renaming 'app/views/contacts/index.haml' to index.html.haml' solved the problem, Rails no longer used index.haml to render the JSON response.