20160726083045_add_more_detail_to_job.rb

class AddMoreDetailToJob < ActiveRecord::Migration[5.0]
  def change
    add_column :jobs, :wage_upper_bound, :integer
    add_column :jobs, :wage_lower_bound, :integer
    add_column :jobs, :contact_email, :string
  end
end

job.rb

class Job < ApplicationRecord
  belongs_to :user
  validates :title, presence: true
  validates :wage_upper_bound, presence: true
  validates :wage_lower_bound, presence: true
  validates :wage_lower_bound, numericality: {greater_than: 0}

  scope :show_public, -> { where("is_hidden = 'false'") } # :is_hidden => false
  scope :recent, -> { order(created_at: :desc) }
end