Getting Started

Random Record is an add on for ActiveRecord to give Rails 3 Models the abilities to access random records

Installation

Random Record is released as a Ruby Gem. The gem is to be installed within a Ruby on Rails 3 application. To install, simply add the following to your Gemfile:

# Gemfile
gem 'random_record'

After updating your bundle, you can use Random function within any ActiveRecord inherited model

Usage

For example you can do something like this in your controller (app/controllers/users_controller.rb), view or presenter

class UsersController < ApplicationController
  RANDOM_LIMIT = 5

  def index
    @users = User.random(RANDOM_LIMIT)
  end

  def show
    @user = User.random
  end
end

Advanced Usage

Random Record is implemented as a Class Method within ActiveRecord Models and can only be attached to the end of a scope chain as it uses eager loading

What does the mean, oh not so wise one?

Rails 3 uses ActiveRecord::Relation for chaining things like scopes, joins, where, or order on your model. This allows Rails to chain these scopes without returning the data until really needed. This is referred to as lazily loading.

This creates a contraint on the implementation of random() method

random() method requires eager loading (required data has to be fetched from the database before creating a random set).

This allows us the append this random method to the end of any Arel chain.

class User < ActiveRecord::Base
  scope :students, where("role = ?", "Student")
end

class UsersController < ApplicationController
  RANDOM_LIMIT = 5

  def index
    @users = User.students.order("created_at DESC").random(RANDOM_LIMIT)
  end

  def show
    @user = User.where("role <> ?", "Student").random
  end
end

But it restricts us to do something like this (use this method within a scope chain)

@user = User.random(2).where("role <> ?", "Student") # Is not going to work