Milind mike1011

Ruby and Rails Interview Questions

Ruby

What is a class?
What is an object?
What is a module? Can you tell me the difference between classes and modules?
Can you tell me the three levels of method access control for classes and modules? What do they imply about the method?
There are three ways to invoke a method in ruby. Can you give me at least two?
Explain this ruby idiom: a ||= b

DigitalOcean Rails/Ubuntu/NGINX (16.04) Setup

Setup
Swapfile
NGINX
ElasticSearch
RVM
Rails
Redis
Postgres

Arel Cheatsheet on Steroids

A (more) complete cheatsheet for Arel, including NamedFunction functions, raw SQL and window functions.

Tables

posts = Arel::Table.new(:posts)
posts = Post.arel_table # ActiveRecord

Table alias

Run rails new --help to view all of the options you can pass to rails new:

$ bin/rails new --help
Usage:
  rails new APP_PATH [options]

Options:
  -r, [--ruby=PATH]                                      # Path to the Ruby binary of your choice
                                                         # Default: /Users/eliot/.rbenv/versions/2.2.0/bin/ruby

Resources:

https://github.com/ankane/searchkick

Indexing

By default, simply adding the call 'searchkick' to a model will do an unclever indexing of all fields (but not has_many or belongs_to attributes).

In practice, you'll need to customize what gets indexed. This is done by defining a method on your model called search_data

def search_data

	http://stackoverflow.com/questions/22667401/postgres-json-data-type-rails-query
	http://stackoverflow.com/questions/40702813/query-on-postgres-json-array-field-in-rails

	#payload: [{"kind"=>"person"}]
	Segment.where("payload @> ?", [{kind: "person"}].to_json)

	#data: {"interest"=>["music", "movies", "programming"]}
	Segment.where("data @> ?", {"interest": ["music", "movies", "programming"]}.to_json)
	Segment.where("data #>> '{interest, 1}' = 'movies' ")
	Segment.where("jsonb_array_length(data->'interest') > 1")

	module Authenticable

	# Devise methods overwrite
	def current_user
	@current_user \|\|= User.find_by(authentication_token: request.headers['Authorization'])
	end

	def authenticate_with_token!
	render json: { errors: "Not authenticated" },
	status: :unauthorized unless user_signed_in?