How to stop being Rails Developer

WHY LIFE WITH RUBY ON RAILS BECOMES
SO HARD AFTER FEW MONTHS OF DEVELOPMENT?
IVAN NEMYTCHENKO

IVAN NEMYTCHENKO
> 14 years in IT
> cofounded 2 IT-companies
> occasional speaker
> coorganized 2 HappyDev conferences
> worked in a startup
> worked as project-manager
> working with Rails since 2006
> author of RailsHurts.com
> internship for ruby junior developers:
SkillGrid
> twitter: @inem

RAILS WORLD is so cool
that we don't even have whole class of problems
millions of java programmers
struggring every day

THESE THINGS MIGHT HELP YOU
> SOLID principles
> Design Patterns
> Refactoring techniques
> Architecture types
> Code smells identification
> Best practices of testing

PRINCIPLES.
MISUNDERSTOOD.
APPLIED.

DRY
«DON'T REPEAT YOURSELF»
RAILSHURTS.COM/_DRY

JUST AVOID DUPLICATION, RIGHT?

«Duplication is far cheaper that
wrong abstraction»
— Sandi Metz

KISS
«KEEP IT SIMPLE, STUPID»
RAILSHURTS.COM/_KISS

ACTIVERECORD
class User < ActiveRecord::Base
end

ACTIVERECORD
> input data coercion
> setting default values
> input data validation
> interaction with the database
> handling nested structures
> callbacks (before_save, etc...)

Polymorphic STI model which belongs to another
polymorphic model through third model, which also has
some valuable JSON data stored in Postgres using
hstore.

WHAT ARE YOU GONNA DO?
> reorganize associations
> become Rails core contributor

PAINFUL BECAUSE OF THE
COMPLEXITY

RAILS IS NOT SIMPLE. IT IS CONVENIENT.

FAT MODEL,
SKINNY CONTROLLER
RAILSHURTS.COM/_SKINNY

BUT IT IS ONLY PART OF THE PROBLEM

YOU SHOULD HAVE NO FAT CLASSES AT ALL

*HINT:
PROPER SOLUTION
REQUIRES THINKING
OUT OF MVC BOX

RAILS
IS NOT YOUR
APPLICATIONRAILSHURTS.COM/_APP

It just doesn't make sense.
Here's my Rails application.
Here's app folder. What's wrong?

HEXXAGONAL ARCHITECTURE
RAILSHURTS.COM/_HEXX

YAGNI«YOU AREN'T GONNA NEED IT»
RAILSHURTS.COM/_YAGNI

WHAT IF YOUR APP
DOESN'T NEED PERSISTANCE YET?

WHAT IF YOUR APP CORE
DOESN'T NEED WEB FRAMEWORK YET?

«Question everything generally
thought to be obvious»
— Dieter Rams

THREE RULES FOR DEVELOPERS
WHO ARE NOT SURE OF ONE'S STRENGTH
> Do not apply DRY principle too early
> Remember about Single Responsibility Principle
> Learn how to apply Design Patterns

FEATURE #1: USERS REGISTRATION

SINGLE TABLE
INHERITANCE !

CONDITIONAL
VALIDATIONS !

BOTH STI AND CONDITIONAL
VALIDATIONS ARE JUST WORKAROUNDS
THE PROBLEM IS DEEPER!

SINGE RESPONSIBILITY PRINCIPLE:
A CLASS SHOULD HAVE
ONLY ONE REASON TO
CHANGE

OUR MODEL KNOWS ABOUT HOW..
> admin form is validated
> org_user form is validated
> guest_user form is validated
> user data is saved

COOKING FORM OBJECT (STEP 1)
class Person
attr_accessor :first_name, :last_name
def initialize(first_name, last_name)
@first_name, @last_name = first_name, last_name
end
end

class Person
attr_accessor :first_name, :last_name
def initialize(first_name, last_name)
@first_name, @last_name = first_name, last_name
end
include ActiveModel::Validations
validates_presence_of :first_name, :last_name
end

class Person
include Virtus.model
attribute :first_name, String
attribute :last_name, String
validates_presence_of :first_name, :last_name
end

FORM OBJECT
class OrgUserInput
include Virtus.model
attribute :login, String
attribute :password, String
attribute :password_confirmation, String
attribute :organization_id, Integer
validates_presence_of :login, :password, :password_confirmation
validates_numericality_of :organization_id
end

USING FORM OBJECT
def create
input = OrgUserInput.new(params)
if input.valid?
@user = User.create(input.to_hash)
else
#...
end
end

FOUR SIMPLE OBJECTS
INSTEAD OF ONE COMPLEX

def redeem
unless bonuscode = Bonuscode.find_by_hash(params[:code])
render json: {error: 'Bonuscode not found'}, status: 404 and return
end
if bonuscode.used?
render json: {error: 'Bonuscode is already used'}, status: 404 and return
end
unless recipient = User.find_by_id(params[:receptor_id])
render json: {error: 'Recipient not found'}, status: 404 and return
end
ActiveRecord::Base.transaction do
amount = bonuscode.mark_as_used!(params[:receptor_id])
recipient.increase_balance!(amount)
if recipient.save && bonuscode.save
render json: {balance: recipient.balance}, status: 200
else
render json: {error: 'Error during transaction'}, status: 500
end
end
end

SINGLE
RESPONSIBILITY
PRINCIPLE

bonuscode.redeem_by(user)
OR
user.redeem_bonus(code)
?

SERVICE OBJECT!
(USE CASE, INTERACTOR)

COOKING SERVICE OBJECT (STEP 1)
class RedeemBonuscode
def redeem
render json: {error: 'Bonuscode not found'}, status: 404 and return
end
if bonuscode.used?
render json: {error: 'Bonuscode is already used'}, status: 404 and return
end
render json: {error: 'Recipient not found'}, status: 404 and return
end
if recipient.save && bonuscode.save
render json: {balance: recipient.balance}, status: 200
else
render json: {error: 'Error during transaction'}, status: 500
end
end
end
end

class RedeemBonuscode
def run!(params)
raise BonuscodeNotFound.new
end
if bonuscode.used?
raise BonuscodeIsAlreadyUsed.new
end
raise RecipientNotFound.new
end
recipient.save! && bonuscode.save!
end
recipient.balance
end
end

def redeem
use_case = RedeemBonuscode.new
begin
recipient_balance = use_case.run!(params)
rescue BonuscodeNotFound, BonuscodeIsAlreadyUsed, RecipientNotFound => ex
render json: {error: ex.message}, status: 404 and return
rescue TransactionError => ex
render json: {error: ex.message}, status: 500 and return
end
render json: {balance: recipient_balance}
end

BUSINESS LOGIC /
CONTROLLER SEPARATION

7 Patterns to Refactor Fat ActiveRecord Models
railshurts.com/_7ways
* * *
Arkency
railshurts.com/_arkency
* * *
Adam Hawkins
railshurts.com/_hawkins

How to stop being Rails Developer

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