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If the migration name is of the form "AddXXXToYYY" or "RemoveXXXFromYYY" and is followed by a list of column names and types then a migration containing the appropriate add_column and remove_column statements will be created.

Creating a table

$ rails g migration CreateUsers email:string:index

db/migrate/20161201203703_create_users.rb

class CreateUsers < ActiveRecord::Migration

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class StringValidator
  ALLOWED_PARANTHESIS = {
    ')' => '(',
    '}' => '{',
    ']' => '['
  }.freeze

  def initialize(value = '')
    @text = value
  end

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• By default rails will set the current utc time for created_at and rails will display them by converting into the application timeone
• You can set application time zone with config.time_zone = 'Eastern Time (US & Canada)'
• You can set application time zone config.active_record.default_timezone = :utc Supports :utc and :local
• Use Time.current wherever possible
• This doesn't work as expected

  Message.where(created_at: '19/01/2018'.to_time.beginning_of_day..'19/01/2018'.to_time.end_of_day)
  Message Exists (0.2ms)  SELECT  1 AS one FROM "messages" WHERE ("messages"."created_at" BETWEEN ? AND ?) LIMIT ?  [["created_at", "2018-01-18 18:30:00"], ["created_at", "2018-01-19 18:29:59.999999"], ["LIMIT", 1]]
  Message Load (0.1ms)  SELECT "messages".* FROM "messages" WHERE ("messages"."created_at" BETWEEN ? AND ?)  [["created_at", "2018-01-18 18:30:00"], ["created_at", "2018-01-19 18:29:59.999999"]]

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Change elasticsearch-rails & elasticsearch-model version

-gem 'elasticsearch-model', '0.1.8'
-gem 'elasticsearch-rails', '0.1.8'
+gem 'elasticsearch-rails', '~> 5.0.2'
+gem 'elasticsearch-model', '~> 5.0.2'

Bundle

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curl -X POST \
     -F "scrape=true" \
     -F "id=https://website.com" \
     https://graph.facebook.com

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Change root password:

sudo passwd

Change user password:

passwd

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List of some "easy to achieve" badges

Badge	Category	Description
Informed	Bronze	Read the entire tour page.
Educated	Bronze	Read the documentation tour.
Autobiographer	Bronze	Complete "About Me" section of user profile
Supporter	Bronze	First up vote.
Backer	Bronze	First example up vote.
Citizen Patrol	Bronze	First flagged post.
Suffrage	Bronze	Use 30 votes in a day.

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I18n Cheatsheet

t('my.messages.hello')

# same as 'my.messages.hello'
t(:hello, scope: 'my.messages')
t(:hello, scope: [:my, :messages])

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{
  "auto_indent": true, /* Optional */
  "draw_white_space": "all", /* Optional */
  "ensure_newline_at_eof_on_save": true, /* Recommended */
  "rulers":
  [
    80
  ], /* Optional */
  "smart_indent": true, /* Optional */
  "tab_size": 2, /* Recommended */

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Preload scoped associations

I have two models User and Post with following associations:

# app/models/user.rb
class User < ActiveRecord::Base
  has_many :posts
end