DCI

Hello There! I’m @patricksroberts. I work at @iorahealth. I co-organize @bostonrb.

DATA CONTEXT INTERACTION

DCI is a strategy to separate what your system does from what your system is.

The Old and Busted Way

# app/models/user.rb class User < ActiveRecord::Base validates_presence_of :twitter_handle def tweet TwitterWrangler.add_to_queue twitter_handle, twitter message end private def twitter_message “Today my BMI is #{body_mass_index} and I’m #{percent_of_body_mass_index_goal} from my goal of #{body_mass_index_goal}!” end end

THE NEW HOTNESS

DATA

# app/models/user.rb class User < ActiveRecord::Base validates_presence_of :twitter_handle end

ROLE

# app/roles/twit_user.rb module TwitUser def twitter_message “Today my BMI is #{body_mass_index} and I’m #{percent_of_body_mass_index_goal} from my goal of #{body_mass_index_goal}!” end end

CONTEXT

# app/contexts/bmi_update_tweet.rb class BmiUpdateTweet attr_reader :user def initialize(user) @user = user @user.extend TwitUser end def call TwitterWrangler.add_to_queue @user.twitter_handle, @user.twitter_message end end

INTERACTION

# app/controllers/tweets_controller.rb class TweetsController < ApplicationController def update user = User.find(params[:id]) BmiUpdateTweet.new(user).call respond_with :ok end end