An example ORM-like contact class

contact.rb

require 'pg'

class Contact
  attr_reader :id, :name, :email

  class << self
    def connection
      @@conn ||= PG.connect(
        dbname: 'contact_list',
        user: 'yorname',
        host: 'localhost'
      )
    end

    def all
      connection.exec("select * from contacts;").map do |row|
        Contact.new(row["id"], row["name"], row["email"])
      end
    end
  end

  def initialize(id, name, email)
    @id = id
    @name = name
    @email = email
  end

  def to_s
    "#{id}: #{name}, \"#{email}\""
  end
end

puts Contact.all