Decisive

# app/controllers/users_controller.rb

class UsersController < ApplicationController
  include ActionController::Live # required to stream; decisive will fall back to rendering without it

  def index
    @users = User.all
  end
end

# app/views/users/index.csv.decisive

csv @users, filename: "users-#{Time.zone.now.strftime("%Y_%m_%d")}.csv" do
  column "Email" # omitted accessor field gets inferred: user.email
  column "Full name", :name # explicit accessor field: user.name
  column "Signed up" do |user| # accepts a block for doing something special
    user.created_at.to_date
  end
end

# app/views/users/index.csv.decisive

csv @users, filename: "users-#{Time.zone.now.strftime("%Y_%m_%d")}.csv", stream: false do |user|
  column "Email"
  column "Full name"

  user.faqs.favorite_questions_and_answers.each do |question, answer|
    column question, answer
  end

  column "Signed up", user.created_at.to_date # we have access to the user record directly
end

# decisive template

csv @records, filename: "report.csv", stream: false do
  ...
end

# controller

class ReportController < ApplicationController
  # include ActionController::Live

  ...
end

# features/support/fix_ac_live.rb
# requiring cucumber/rails requires rails/test_help which requires action_controller/test_case which redefines AC::Live#new_controller_thread to be single threaded, which breaks our downloads
# set it back to original method definition

module ActionController
  module Live
    silence_redefinition_of_method :new_controller_thread
    def new_controller_thread # :nodoc:
      Thread.new {
        t2 = Thread.current
        t2.abort_on_exception = true
        yield
      }
    end
  end
end