500Tech / Rails Riddles #2

user.rb

# Improve / Fix as many things in the code below
# Answers should be sent to [email protected]
# Good luck

class User < ActiveRecord::Base
  validates_presence_of :name, :email, :date_of_birth, :age_category

  before_save do
    age = (Time.now - date_of_birth).year
    if age < 10 age_category = 'child'
    elsif age < 18 age_category = 'teenager'
    elsif age < 24 age_category = 'young'
    elsif age < 54 age_category = 'adult'
    else age_category = 'senior'
  end
end

Send answers privately to [email protected]. No spoilers!

Improvement number 1 - name your callback!

before_save :set_age_category

protected
def set_age_category
...

Improvement number 2 - use small methods for reusablility and readability

def age
  (Time.now - date_of_birth).year
end

def set_age_category
  if age < 10....
end

Fix number 1 - trying to set an active record attribute from within a method requires an explicit use of 'self':

def set_age_category
  ...
  self.age_category = ...
end

Improvement number 3 - use array and loop over a hash to set the age category (many other possible solutions for this):

CATEGORIES = [[10, 'child'],
                               [18, 'teenager'],
                               [24, 'young'],
                               [54, 'adult'],
                               [200, 'senior']]
...
def set_age_category
  self.age_category = CATEGORIES.take_while { |category| category[0] < age}.last[1]
end

Improvement number 4 - define age_category as a method so that whenever we use it it's correct (and not just after we save):

def age_category
   CATEGORIES.take_while { |category| category[0] < age}.last[1]
end

def set_age_category
  self[:age_category] = age_category
end

Fix number 2 - don't validate age_category (because it is a calculated field)

validates_presence_of :name, :email, :date_of_birth
```ruby