Ian Kiku iankiku

GROKKING NOTES

I liked the way Grokking the coding interview organized problems into learnable patterns. However, the course is expensive and the majority of the time the problems are copy-pasted from leetcode. As the explanations on leetcode are usually just as good, the course really boils down to being a glorified curated list of leetcode problems.

So below I made a list of leetcode problems that are as close to grokking problems as possible.

Pattern: Sliding Window

JWT Auth + Refresh Tokens in Rails

This is just some code I recently used in my development application in order to add token-based authentication for my api-only rails app. The api-client was to be consumed by a mobile application, so I needed an authentication solution that would keep the user logged in indefinetly and the only way to do this was either using refresh tokens or sliding sessions.

I also needed a way to both blacklist and whitelist tokens based on a unique identifier (jti)

Before trying it out DIY, I considered using:

Run rails new --help to see all of the options you can use to create a new Rails application:

Output for Rails 8+

Usage:
  rails COMMAND [options]

You must specify a command:

First of all, please note that token expiration and revoking are two different things.

Expiration only happens for web apps, not for native mobile apps, because native apps never expire.
Revoking only happens when (1) uses click the logout button on the website or native Apps;(2) users reset their passwords; (3) users revoke their tokens explicitly in the administration panel.

1. How to hadle JWT expiration

A JWT token that never expires is dangerous if the token is stolen then someone can always access the user's data.

Quoted from JWT RFC:

Forms, `form_for`, and `link_to`

Lesson Objectives

Understand forms and the ways we write them
Understand the difference between form_tag and form_for
Understand link_to and how we can use it to dynamically link our application together

	name: Ruby

	on:
	push:
	branches: [ master ]
	pull_request:
	branches: [ master ]

	jobs:
	build:

	https://stackoverflow.com/a/1888569/11842937

	In MySQL:

	SELECT *
	FROM mytable
	WHERE record_date >= NOW() - INTERVAL 1 DAY
	In SQL Server:

	SELECT *

	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")

	# Also @see https://www.viget.com/articles/protip-passing-parameters-to-your-rake-tasks for
	# examples using dependents and default values for arguments (see the updates at the end)

	# Avdi Grimm's rake tutorial is really helpful. His section on FileLists:
	# @see http://www.virtuouscode.com/2014/04/22/rake-part-2-file-lists/


	# Rails:
	# * to get access to Rails models, etc, your task must depend on the :environment task
	# ex: task :my_task => :environment do ....

	"""Download sentry data.
	usage:

	python download_sentry_data.py <org>/<project> <api_key>

	"""
	import requests
	import csv