FormObject for building complex forms Dmytro Piliugin @suaron [email protected] 

MVC Model Controller View 

MVC Model Controller View 

MVC Model Controller View FromObject 

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1 class SignupsController < ApplicationController! 2 def new! 3 @signup_form = SignUpForm.new! 4 end! 5 ! 6 def create! 7 @signup_form = SignUpForm.new(params)! 8 if @signup_form.save! 9 redirect_to home_path! 10 else! 11 render :new! 12 end! 13 end! 14 end 

1 class SignUpForm! 2 include ActiveModel::Model! 3 ! 4 attr_reader :user! 5 attr_reader :items! 6 ! 7 def initialize(params = {})! 8 @user = User.new(user_params(params))! 9 @items = build_items(items_params(params))! 10 end! 11 ! 12 def build_items(items_attributes)! 13 items_attributes.map do |attributes|! 14 Item.new(attributes)! 15 end! 16 end! 17 ! 18 def user_params(params)! 19 params.fetch(:user, {}).slice(:email).to_hash! 20 end! 21 ! 22 def items_params(params)! 23 params.fetch(:user, {}).fetch(:items, {}).values.map do |item_hash|! 24 item_hash.slice(:title).to_hash! 25 end! 26 end! 27 ! 28 end 

1 class SignUpForm! 2 include ActiveModel::Model! 3! 4 ...! 5 ! 6 def save! 7 valid? && persist! 8 end! 9 ! 10 validate :at_least_one_item_should_be_presence! 12 def at_least_one_item_should_be_presence! 13 if @items.empty?! 14 errors.add(:items, 'at least one should be present')! 14 end! 15 end! 16 ! 17 def valid?! 18 super! 19 @user.valid?! 20 @items.each(&:valid?)! 21 errors.empty? && @user.errors.empty? \! 22 && @items.all?{ |item| item.errors.empty? }! 23 end! 24 ! 25 ...! 26! 27 end 

1 class SignUpForm! 2 include ActiveModel::Model! 3 ! 4 ...! 18 ! 19 def save! 20 valid? && persist! 21 end! 22 ! 23 ...! 34! 41 private! 42 def persist! 43 ActiveRecord::Base.transaction do! 44 company = Company.create!! 45 order = company.orders.create!! 46 ! 47 @user.company = company! 48 @user.save!! 49 ! 50 @items.each do |item|! 51 item.order = order! 52 item.save!! 53 end! 54 ! 55 return true! 56 end! 57 end! 58 ! 59 ...! 87! 88 end 

41 private! 42 def persist! 43 ActiveRecord::Base.transaction do! 44 company = Company.create!! 45 order = company.orders.create!! 46 ! 47 @user.company = company! 48 @user.save!! 49 ! 50 @items.each do |item|! 51 item.order = order! 52 item.save!! 53 end! 54 ! 55 AdminMailer.delay.notify(order.id)! 56 ! 57 return true! 58 end! 59 end 

41 private! 42 def persist! 43 ActiveRecord::Base.transaction do! 44 company = Company.create!! 45 order = company.orders.create!! 46 ! 47 @user.company = company! 48 @user.save!! 49 ! 50 @items.each do |item|! 51 item.order = order! 52 authorize_and_save(item)! 53 end! 54 ! 55 return true! 56 end! 57 end! 58 ! 59 def authorize_and_save(object)! 60 if current_ability.can?(:create, object)! 61 object.save!! 62 else! 63 errors.add(:security, "not authorised")! 64 raise ActiveRecord::Rollback! 65 end! 66 end 

slides: https://speakerdeck.com/suaron/ formobject-for-building-complex-forms/ code: http://github.com/suaron/fo 

References • http://railscasts.com/episodes/416-form-objects • http://matthewrobertson.org/blog/2012/09/20/ decoupling-rails-forms-from-the-database/ • http://robots.thoughtbot.com/activemodel-form- objects • http://pivotallabs.com/form-backing-objects-for-fun- and-profit/ 

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