Milan Rawal codemilan

Transactions

As your business logic gets complex you may need to implement transactions. The classic example is a bank funds transfer from account A to account B. If the withdrawal from account A fails then the deposit to account B should either never take place or be rolled back.

Basics

All the complexity is handled by ActiveRecord::Transactions. Any model class or instance has a method named .transaction. When called and passed a block, that block will be executed inside a database transaction. If there's an exception raised, the transaction will automatically be rolled back.

Example

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

Installation

Install fish via Brew
Optionally install Oh My Fish!
Add fish to known shells
Set default shell to fish

brew install fish  
curl -L https://get.oh-my.fish | fish

	# Adapted from https://rubyplus.com/articles/3401-Customize-Field-Error-in-Rails-5
	ActionView::Base.field_error_proc = Proc.new do \|html_tag, instance\|
	html = ''

	form_fields = [
	'textarea',
	'input',
	'select'
	]

	require 'net/ftp'

	CONTENT_SERVER_DOMAIN_NAME = "one-of-the-ftp-server.thought-sauce.com.hk"
	CONTENT_SERVER_FTP_LOGIN = "saucy-ftp-server-login"
	CONTENT_SERVER_FTP_PASSWORD = "saucy-ftp-server-password"


	# LOGIN and LIST available files at default home directory
	Net::FTP.open(CONTENT_SERVER_DOMAIN_NAME, CONTENT_SERVER_FTP_LOGIN, CONTENT_SERVER_FTP_PASSWORD) do \|ftp\|
	files = ftp.list

	#!/usr/bin/env bash
	#
	# Simple script to setup friendly environment for beginning Linux/Mac Ruby users
	#

	echo "installing pry and awesome_print"
	gem install -q --no-ri --no-rdoc \
	pry pry-doc pry-coolline awesome_print

	# Nifty pry config copied from https://github.com/dotphiles/dotphiles/blob/master/ruby/aprc

	# This probably isn't a good thing to want to do, but it came up for me,
	# so in the spirit of helping others with weird problems (and because this
	# seems to be documented almost nowhere):

	after_save do

	if some_failing_condition
	errors.add(:something, "some failure happened.")
	raise ActiveRecord::RecordInvalid.new(self)
	end

	# Ref:- 'https://gist.github.com/tadast/9932075'
	# Inside your rails app root directory.
	# run "mkdir config/certs && touch config/certs/.keep"
	# Add below two lines in .gitignore
	# /config/certs/*
	# !/config/certs/.keep

	# Add below code in config/puma.rb

	if Rails.env.development?

	# https://www.justinweiss.com/articles/search-and-filter-rails-models-without-bloating-your-controller/
	# Call scopes directly from your URL params:
	#
	# @products = Product.filter(params.slice(:status, :location, :starts_with))
	module Filterable
	extend ActiveSupport::Concern

	module ClassMethods

	# Call the class methods with the same name as the keys in <tt>filtering_params</tt>

	# This server demo does a socket hijack in Rack and then saves the socket to a global variable
	# to prevent it from being GCed when the Puma thread ends. It will then write "BEEP" to each
	# socket every ten seconds to prevent the connection timing out. During testing, it easily
	# handled up to 65523 connections, after which it ran into the `ulimit` for open file descriptors.
	# The bit with the waiting area is there because a normal `Set` is not thread safe and it would
	# drop socket due to race conditions. The `Queue` is thread safe and will make sure all sockets
	# are preserved.

	# run with `rackup -q -p 8000 -o 0.0.0.0 c10k.ru`
	# testing: install `ab` and then run `ab -c 20000 -n 20000 <ip adress of server>:8000/