Kiev-rb#2

1. FormObject for building
complex forms
Dmytro Piliugin
@suaron
dmytro.piliugin@gmail.com

2. MVC
Model
M odel
Controller
View

3. MVC
Model
M odel
Controller
View

4. MVC
Model
M odel
Controller
FromObject
View

8. 1 class SignupsController < ApplicationController
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def new
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@signup_form = SignUpForm.new
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end
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def create
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@signup_form = SignUpForm.new(params)
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if @signup_form.save
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redirect_to home_path
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else
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render :new
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end
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end
14 end

9. 1 class SignUpForm
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include ActiveModel::Model
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attr_reader :user
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attr_reader :items
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def initialize(params = {})
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@user = User.new(user_params(params))
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@items = build_items(items_params(params))
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end
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def build_items(items_attributes)
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items_attributes.map do |attributes|
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Item.new(attributes)
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end
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end
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def user_params(params)
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params.fetch(:user, {}).slice(:email).to_hash
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end
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def items_params(params)
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params.fetch(:user, {}).fetch(:items, {}).values.map do |item_hash|
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item_hash.slice(:title).to_hash
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end
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end
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28 end

10. 1 class SignUpForm
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include ActiveModel::Model
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...
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def save
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valid? && persist
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end
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validate :at_least_one_item_should_be_presence
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def at_least_one_item_should_be_presence
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if @items.empty?
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errors.add(:items, 'at least one should be present')
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end
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end
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def valid?
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super
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@user.valid?
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@items.each(&:valid?)
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errors.empty? && @user.errors.empty?
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&& @items.all?{ |item| item.errors.empty? }
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end
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...
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27 end

11. 1 class SignUpForm
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include ActiveModel::Model
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...
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def save
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valid? && persist
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end
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...
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private
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def persist
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ActiveRecord::Base.transaction do
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company = Company.create!
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order = company.orders.create!
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@user.company = company
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@user.save!
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@items.each do |item|
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item.order = order
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item.save!
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end
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return true
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end
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end
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...
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88 end

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private
def persist
ActiveRecord::Base.transaction do
company = Company.create!
order = company.orders.create!
@user.company = company
@user.save!
@items.each do |item|
item.order = order
item.save!
end
AdminMailer.delay.notify(order.id)
return true
end
end

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private
def persist
ActiveRecord::Base.transaction do
company = Company.create!
order = company.orders.create!
@user.company = company
@user.save!
@items.each do |item|
item.order = order
authorize_and_save(item)
end
return true
end
end
def authorize_and_save(object)
if current_ability.can?(:create, object)
object.save!
else
errors.add(:security, "not authorised")
raise ActiveRecord::Rollback
end
end

14. slides:
https://speakerdeck.com/suaron/formobject-for-buildin
/
code: http://github.com/suaron/fo

15. References
•
http://railscasts.com/episodes/416-form-objects
•
http://matthewrobertson.org/blog/2012/09/20/decoupling-
•
http://robots.thoughtbot.com/activemodel-form-objects
•
http://pivotallabs.com/form-backing-objects-for-funand-profit/

16. Q/A