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

mike1011

######################################  UBUNTU  ###############################################

==== to search by port ======
lsof -wni tcp:3000

==== to kill by port ========
sudo kill -9 `sudo lsof -t -i:3000`
==== another way to search and kill a process using port ===
sudo lsof -i -P -n | grep 6379
sudo kill  -9 <process_id>

mike1011

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")

mike1011

Use Case - Use Devise Confirmable module to confirm newly added organization(org) using email(association)

We want Three things to work - 
     Use confirmable - send_confirmation_instructions to send email when new org is added
     Define Routes - organization_confirmation_url, so that user can use this route to confirm the org
     Add confirmable columns inside existing organizations table, update token,timestamps on db
     
====== HERE WE START =========     
- `organization.rb`
	has_one :contact_detail ##contains email

mike1011

Do you have spaces in your Windows username?

1. Create a new account on Windows without a space.

#Installation

1. Download cygwin from http://cygwin.com
2. Run setup-(x86|x86_64).exe
3. Click next until selecting repo to download packages
4. Choose http://cs.vt.edu (gotta go fast), click next

mike1011

First, setup and install monit on Ubuntu server
   ###get the latest
   sudo apt-get update
   ##install monit
   sudo apt-get install monit
   ##edit monit and add the below custom scripts
   sudo vim /etc/monit/monitrc
   ##reload and verify
   sudo monit reload
   sudo monit

mike1011

# this monit config goes in /etc/monit/conf.d

check process puma_master
  with pidfile  /data/myapp/current/tmp/puma.pid
  start program = "/etc/monit/scripts/puma start"
  stop program = "/etc/monit/scripts/puma stop" 
  group myapp

check process puma_worker_0
  with pidfile /data/myapp/current/tmp/puma_worker_0.pid

mike1011

stats = Sidekiq::Stats.new

stats.queues

stats.enqueued

stats.processed

stats.failed

mike1011

#Make sure heroku toolbelt and rvm are installed
#heroku toolbelt available to download on their site, rvm available via curl
\curl -sSL https://get.rvm.io | bash -s stable --ruby

rvm use "2.1.1"
rvm use --create 2.1.1@project 
gem install rails 

#if using postgres (good for heroku) pass argument to 'rails new'
rails new project --database=postgresql

mike1011

require 'aws-sdk'
  
s3 = Aws::S3::Resource.new(
  region: 'us-east-1',
  credentials: Aws::InstanceProfileCredentials.new()
)
bucket =  s3.bucket('my-daily-backups')

file = (DateTime.now).strftime("%Y.%m.%d-backup")
if bucket.object(file).exists?