Pexels - Applicant Qualification Test

question2.1.txt

### Question 2.1

1. In the show action of PostsController we create a new instance variable called "@post" and use the ActiveRecord ORM to generate a SQL query for our database that returns a collection of all entries in the "posts" table that have attribute "published = true" and where the "id" attribute from the "params" hash matches the "id" of the "post" entry.

We then use the ORMs "first" method to select the first object from the collection.

In the next line we check if "@post" is undefined or nil. If it is we set "@post" to the newest / latest entry in the database.

In the "posts/show" view we iterate over the "comments" for a "post" (usually identified by "post_id" attribute on "comment"), insert a paragraph for each comment and fetch and display the "user.name" and the "text" of the "comment".

question2.2.1.rb

### Question 2.2.1

# change

class PostsController < ApplicationController
  def show
    @post = Post.where("published = true").where("id = #{params[:id]}").first
    @post ||= Post.last
  end
end

# to

class PostsController < ApplicationController
  def show
    @post = Post.where(published: true).find_by(id: params[:id]) || Post.last
  end
end

# I would change the code as shown above to
# - avoid SQL injection attackes as described here: https://www.netsparker.com/blog/web-security/sql-injection-ruby-on-rails-development/
# - make it more concise
# - only return single post for a specific id - for all DBs that I worked with so far the id column had to be unique

question2.2.2.erb

<%# Question 2.2.2 %>

<%# change %>

<% @post.comments.each do |comment| %>
  <p>
    <b><%= comment.user.name %> wrote a comment:</b>
    <%= comment.text %>
  </p>
<% end %>

<%# to %>

<% @post.comments.each do |comment| %>
  <p>
    <b><%= comment&.user&.name %> wrote a comment:</b>
    <%= comment&.text %>
  </p>
<% end %>

<%# I would change the code as shown above to avoid getting errors if either "user" is "nil" or "name" is "nil". The Safe Navigation Operator was introduced with ruby 2.3.0, if an older ruby is used we should probably check with <% if comment.user && comment.user.name %> %>

reverse_string.rb

# Returns the input string in reverse order
#
# Examples:
# reverse_string('photography') => "yhpargotohp"
# reverse_string('super photography') => "yhpargotohp repus"
def reverse_string(input)
  # verify that input parameter is a String
  raise ArgumentError.new("Please provide a String") if !input.is_a? String

  # verify that input parameter is not empty
  raise ArgumentError.new("Input may not be empty") if input.empty?

  # iterate over each character of input string and
  # prepend to input_reverse, thereby reversing the string
  input_reverse = ''
  input.each_char { |c| input_reverse.prepend(c) }
  input_reverse
end

reverse_string_test.rb

require 'minitest/autorun'
require_relative 'reverse_string'

class TestReverseString < MiniTest::Unit::TestCase
  def test_reverse_string
    assert_equal "yhpargotohp", reverse_string('photography')
  end

  def test_reverse_string_with_spaces
    assert_equal "yhpargotohp repus", reverse_string('super photography')
  end

  def test_argument_with_non_string_types
    assert_raises ArgumentError do
      reverse_string(1)
    end
  end

  def test_empty_string
    assert_raises ArgumentError do
      reverse_string('')
    end
  end
end