Nick Soto nicksoto

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

RFC Template

Feature Name: (fill me in with a unique identity, myawesomefeature)

Start Date: (fill me in with today's date, YYYY-MM-DD)

Author: (your names)

Related components/issues: (if any)

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.

Effective Engineer - Notes

By Edmond Lau
Highly Recommended 👍
http://www.theeffectiveengineer.com/

What's an Effective Engineer?

Requirements

Minikube requires that VT-x/AMD-v virtualization is enabled in BIOS. To check that this is enabled on OSX / macOS run:

sysctl -a | grep machdep.cpu.features | grep VMX

If there's output, you're good!

Prerequisites

Integrate Gem/Engine and main Rails app

Overview

Paths
Routes
Add functionality to controller
Improving (Extending or overriding) Engine functionality
Helpers
Assets

This is an example of how I combine interaction/service classes with Wisper event broadcasting in Rails.

In this example, I show a UsersController#create API, a corresponding service object, and all the test code/listeners to make it all happen.

The outcome is:

Concepts in your system ("Signing up a user", "Creating an order") have a single entry point in your codebase, vs. making raw ActiveRecord calls to object.save in dozens of places.
Since your concept has one entry point (the service class), you can easily grep for usage of it.
Stupid easy to attach listeners to the service class
All event listeners are very small and easily unit tested

	apiVersion: v1
	kind: ReplicationController
	metadata:
	name: kube-registry-v0
	namespace: kube-system
	labels:
	k8s-app: kube-registry
	version: v0
	spec:
	replicas: 1

	# 1) Create your private key
	$ cd ~/.ssh
	$ openssl genrsa -des3 -passout pass:x -out lvh.me.pass.key 2048

	# 2) Generate RSA key
	$ openssl rsa -passin pass:x -in lvh.me.pass.key -out lvh.me.key

	# 3) Get rid of private key
	$ rm lvh.me.pass.key

	#!/bin/bash

	while [[ $# -gt 1 ]]
	do
	case "$1" in
	-f \| --file)
	file="$2"
	shift 2
	;;
	-h \| --hostname)

	# Wouldn't it be great if you could have STI like functionality
	# without needing to encode strings of class names in the database?
	# Well today is your lucky day! Discriminable Model is here to help.
	#
	# Simply specify your models desired type column, and provide a block to
	# do the discrimination. If you want the whole STI-esque shebang of properly
	# typed finder methods you can supply an array of 'discriminate_types' that will
	# be used to apply an appropriate type.
	#
	# class MyModel < ActiveRecord::Base