artificemm

Semantic Commit Messages

See how a minor change to your commit message style can make you a better programmer.

Format: <type>(<scope>): <subject>

<scope> is optional

Example

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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")

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# from_cte_sql = ::Namespace::From.where_clause
# ..


from_table = Arel::Table.new(:from_lane)
to_table = Arel::Table.new(:to_lane)
rates_table = Arel::Table.new(:rates)

rates_table
  .join(from_table).on(rates_table[:from_id].eq(from_table[:id]))

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module Navigable
    extend ActiveSupport::Concern

    def next
        self.class.where("id > ?", self.id).order(id: :asc).first
    end

    def previous
        self.class.where("id < ?", self.id).order(id: :desc).first
    end

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require 'set'

# Solved exercises 
# Roberto Ruiz
# For Tinnova

# 1:
input = [{ "name": 'eggs', "price": 1 }, { "name": 'coffee', "price": 9.99 }, { "name": 'rice', "price": 4.04 }]

def sort_hash_by_price(ary)

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function calculateDistance(rssi) {
  
  var txPower = -59 //hard coded power value. Usually ranges between -59 to -65
  
  if (rssi == 0) {
    return -1.0; 
  }

  var ratio = rssi*1.0/txPower;
  if (ratio < 1.0) {

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Pry Cheat Sheet

• Youtube Tutorial 2013

Command Line

• pry -r ./config/app_init_file.rb - load your app into a pry session (look at the file loaded by config.ru)
• pry -r ./config/environment.rb - load your rails into a pry session

Debugger

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--- Debian

sudo apt-get --ignore-missing install build-essential git-core curl openssl libssl-dev libcurl4-openssl-dev zlib1g zlib1g-dev libreadline6-dev libyaml-dev libsqlite3-dev libsqlite3-0 sqlite3 libxml2-dev libxslt1-dev libffi-dev software-properties-common libgdm-dev libncurses5-dev automake autoconf libtool bison postgresql postgresql-contrib libpq-dev pgadmin3 libc6-dev nodejs -y

curl -sSL https://rvm.io/mpapis.asc | gpg --import -
curl -sSL https://get.rvm.io | bash -s stable
source ~/.rvm/scripts/rvm

rvm install 2.6.2
rvm use 2.6.2 --default

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#SOLID Principles with ruby examples

##SRP - Single responsibility principle A class should have only a single responsibility.

Every class should have a single responsibility, and that responsibility should be entirely encapsulated. All its services should be narrowly aligned with that responsibility, this embrace the high cohesion.

##OCP - Open/closed principle Software entities should be open for extension, but closed for modification.

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function loadJson(callback) {
	var XmlHttpRequest = new XMLHttpRequest();
	XmlHttpRequest.overrideMimeType("application/json");
	XmlHttpRequest.open('GET', 'file.json', true);
	XmlHttpRequest.onreadystatechange = function () {
		if (XmlHttpRequest.readyState == 4 && XmlHttpRequest.status == "200") {
			// .open will NOT return a value 
			// but simply returns undefined in async mode so use a callback
			callback(XmlHttpRequest.responseText);
		}