ActiveRecordLazyFindBy provides simple lazy methods that be able to reduce SQL issuance slightly.

Add this line to your application's Gemfile:

gem 'active_record_lazy_find_by'

And then execute:

$ bundle

Or install it yourself as:

$ gem install active_record_lazy_find_by

For example, you have defined the following table and class:

# == Schema Information
#
# Table name: users
#
#  id         :integer          not null, primary key
#  name       :string           not null
#  age        :integer          not null
#  created_at :datetime         not null
#  updated_at :datetime         not null
#

class User < ApplicationRecord
  include ActiveRecordLazyFindBy::Methods

  has_many :posts
end

The lazy_find_by returns an instance that does not execute SQL until it is needed.

user = User.lazy_find_by(id: 1, name: "foo")

user.id
#=> 1
user.name
#=> "foo"
user.age
  User Load (0.4ms)  SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
#=> 39

It executes SQL for relations, but it does not execute SQL for users table.

user = User.lazy_find_by(id: 1, name: "foo")
user.posts.find_by(id: 1)
  Post Load (0.3ms)  SELECT "posts".* FROM "posts" WHERE "posts"."user_id" = ? AND "posts"."id" = ? LIMIT ?  [["user_id", 1], ["id", 1], ["LIMIT", 1]]
#=> #<Post id: 1, user_id: 1, title: "bar", created_at: "2019-05-10 15:44:39", updated_at: "2019-05-10 15:44:39">

This gem provides the lazy_find method that be able to pass only id attribute.

user = User.lazy_find(1)
user.id
#=> 1
user.name
  User Load (0.4ms)  SELECT "users".* FROM "users" WHERE "users"."id" = ? LIMIT ?  [["id", 1], ["LIMIT", 1]]
#=> "dhh"

lazy_find_by and lazy_find methods does not execute SQL immediately, so an instance that returns by these methods may be older than databases.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/sinsoku/active_record_lazy_find_by. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the ActiveRecordLazyFindBy project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.