Eval

eval.rb

#Palindrome a word phrase that reads the same backwards
# write code that will return true for the following palindrome
#  "A man, a plan, a canal: Panama"
module Palindrome
  def self.is_palindrome(word)
    normalized = word.downcase.gsub(/\W/, '')
    normalized == normalized.reverse
  end
end

# Palindrome.is_palindrome("A man, a plan, a canal: Panama") => true

##############################################################################################################################
#What would you say is wrong with this code
class CommentsController < ApplicationController
  def users_comments
    posts = Post.all
    comments = posts.map(&:comments).flatten
    @user_comments = comments.select do |comment|
      comment.author.username == params[:username]
    end
  end
end

# 1. I would do the user lookup first
# 2. Mapping over the entire posts table to reduce it into a list of comments is going
#    to take forever...
# 3. It looks like comment.author is a user. I would make sure the field is a foreign
#    key reference to user, so that you could just do user.comments

class CommentsController < ApplicationController
  def users_comments
    user = User.where(username: params[:username])
    @user_comments = user.comments
  end
end

##############################################################################################################################
files = {
    'Input.txt' => 'Randy',
    'Code.py' => 'Stan',
    'Output.txt' => 'Randy'
}

module FileOwners
  def self.group_by_owners(files)
    files.reduce({}) do |result, (file, owner)|
      if result[owner]
        result[owner].push(file)
      else
        result[owner] = [file]
      end
      result
    end
  end
end

puts FileOwners.group_by_owners(files)
 #returns hash containing array of file names
 # for each owner
 # {randy => [Input.text, Output.txt], stand => [Code.py]}
#
##############################################################################################################################
# How would you define a Person model so that any Person can be
# assigned as a parent of another Person.
# What columns would you need to define in the migration creating the table for person
# so you could do the following
# john = Person.create(name: "John")
# jim = Person.create(name: "Jim", parent: john)
# bob = Person.create(name: "Bob", parent: john)
# john.children.map(&:name)
# => ["Jim", "Bob"]
#

class Person < ActiveRecord::Base
  belongs_to :parent, class_name: 'Person', optional: true
  has_many :children, class_name: 'Person'
end

def change
  add_reference :users, :parent_id, index: true, null: true
end
##############################################################################################################################
#config/routes.rb
# what routes, http verbs will the following snippet generate
resources :posts do
  member do
    get 'comments'
  end
  collection do
    post 'bulk_upload'
  end
end

# GET, POST to /posts
# GET to /posts/new
# GET to /posts/:id/edit
# GET, PUT, PATCH, DELETE to /posts/:id
# GET to /posts/:id/comments
# GET to /posts/bulk_upload