Skip to content

Instantly share code, notes, and snippets.

View esquinas's full-sized avatar

Enrique Esquinas esquinas

19 followers · 87 following
  • Asturias, Spain
View GitHub Profile
@esquinas
esquinas / test_n_plus_ones_spec.rb
Last active January 25, 2024 15:40
Tests N+1 queries in Rails using RSpec
# frozen_string_literal: true
RSpec.describe TestNPlusOnes do
describe "<something>" do
subject(:generate) { puts("<Do something with the DB>") }
# Technique seen in ActiveRecord's #assert_queries_count to use with Minitest:
# https://github.com/rails/rails/blob/0496a5f994f134695bf7bdc02dacdf24925bc67c/activerecord/lib/active_record/testing/query_assertions.rb#L99
it "avoids N+1 queries" do
number_of_queries = 0
counter = ->(*, payload) {
@esquinas
esquinas / 20180523_Create_a_database_Exercise41.md
Last active May 7, 2023 11:28
SmartNinja WD2

Exercise 4.1 - Solutions:

Design

Job Board Database Design schema on Imgur

Create tables

-- Temporal.
@esquinas
esquinas / google-sheet-visibility.gs
Last active January 3, 2023 18:54
Check visibility of hidden rows and columns in Google Spreadsheet App Script
/*
USAGE EXAMPLES:
Is the tenth row hidden?
> isRowHidden(sheet.getRange('B10'))
Is column B hidden?
> isColumnHidden(sheet.getRange('B10'))
Is cell B10 visible? (not in a hidden row and/or column)
@esquinas
esquinas / sql_fiddling.sql
Last active September 2, 2022 15:35
How to play with SQL with no actual table (POSTGRES flavor)
-- WINDOW EXAMPLE:
SELECT id
, col1
, col2
, bool_col
, datecuen
, (CASE WHEN bool_col IS NOT NULL
THEN SUM(col1) OVER win1
+ SUM(col2) OVER win1
ELSE 0
@esquinas
esquinas / cantor_functions.rb
Created September 29, 2021 12:14
Ruby implementation of the Cantor pairing function to uniquely encode two natural numbers into a single natural number while being order sensitive.
# LINK: https://en.wikipedia.org/wiki/Pairing_function#Cantor_pairing_function
# LINK: https://www.cantorsparadise.com/cantor-pairing-function-e213a8a89c2b
def inv_cantor(z)
w = ((Math.sqrt(8.0*z.to_f + 1.0) - 1.0) / 2.0).floor
t = (w**2 + w) / 2
y = (z - t)
x = (w - y)
[x, y]
end
@esquinas
esquinas / json_create_additions_example.rb
Last active May 7, 2021 09:38
Example for Ruby JSON.parse option create_additions?
require 'json'
class Person
attr_accessor :name, :age
def initialize(name, age)
@name = name
@age = age
end
@esquinas
esquinas / mongo_id_from_date.rb
Last active December 24, 2020 10:59
Convert a timestamp to MongoDB ObjectId to get fast (indexed) create_at queries for free.
# USAGE:
# ------
# mongo_id_from_date Date.parse('2020-12-24') # => "5fe3da000000000000000000"
# mongo_id_from_date(Time.now) # => "5fe471d90000000000000000"
def mongo_id_from_date(date)
min_date = Time.at 0
max_date = Time.at 0xffffffff
raise "Error: date must be between #{min_date.to_date} and #{max_date.to_date}" if date < min_date || date > max_date
@esquinas
esquinas / gist:3291de1c711fa6816daedddf3402e9bd
Created December 9, 2020 14:34
Script to check ruby syntax of all Ruby files in project directory.
#!/usr/bin/env bash
echo 'STATIC-CHECKING RUBY SYNTAX OF ALL RB & RAKE FILES IN PROJECT'
echo
find . | grep ".*\.rb$" | xargs -L 1 ruby -c
find . | grep ".*\.rake$" | xargs -L 1 ruby -c
@esquinas
esquinas / number_to_base64.rb
Last active August 25, 2020 15:37
Convert integers (or hex ids) into url-safe base64 strings saving space compared to hexadecimal (like Mongo) IE: "b380d04df5a7ea1d22cc4a54" could be passed as "s4DQTfWn6h0izEpU" in an url param saving 8 characters.
# frozen_string_literal: true
require 'base64'
def number_to_base64(number, base: nil)
valid_base = ->(b) {
b.is_a?(Integer) && b > 1
}
hex2int = ->(hex_chars) {
hex_chars.to_i(16)
@esquinas
esquinas / hash_to_struct.rb
Last active July 23, 2020 13:18
Monkeypatch to mock this feature https://bugs.ruby-lang.org/issues/16986 but using a Hash#to_struct method.
# Usage:
# my_struct = { alpha: 1, beta: 2, 'charlie' => 3 }.to_struct
# my_struct.alpha # => 1
# my_struct.beta # => 2
# my_struct.charlie # => 3
# Remember, to compare structs: `my_struct.to_h == other_struct.to_h`
#
# Usage to get deep structs:
# my_deep_struct = {
# email: 'alice@example.com',