RedisAssist - Easy Redis Backed Object Modeling

RedisAssist is a Persistant Object Model backed by Redis for Ruby.

Store and Fetch data of any type in Redis with as little friction as possible. RedisAssist lets you back simple or complex Object Models with Redis while giving you a convenient interface interact with it.

In progress RDoc: http://www.rubydoc.info/github/endlessinc/redis_assist/frames

Getting Started

In your Gemfile:

gem "redis_assist"

Create a model:

class Person < RedisAssist::Base
  attr_persist :name
  attr_persist :birthday,     as: :time
  attr_persist :meta_info,    as: :json
  attr_persist :created_at,   as: :time # Magic date fields just like ActiveRecord.

  def validate
    add_error(:name, "Albert Einstein is dead.") if name.eql?('Albert Eintein')
  end 
end

Saving

person = Person.new(name: 'Albert Hoffman', birthday: Time.parse('1/11/1906'), meta_info: { profession: 'Scientist' })
person.new_record?  # => true
person.name         # => "Albert Hoffman"
person.save         # => #<Person:0x007f88341662a0>
person.new_record?  # => false

Creating

person = Person.create(name: 'Albert Hoffman', birthday: Time.parse('1/11/1906'), meta_info: { profession: 'Scientist' })

Updating

With an instance

person = Person.find(1)
person.name = 'Hubble Love'
person.save

Skip callbacks / validations

person.update_columns(name: 'Tyler Love', birthday: Time.parse('1/11/1908'))

With only an id, this will hit callbacks and validations

Person.update(1, name: 'Tyler Love')

Validating

person = Person.new(name: 'Albert Einstein', birthday: Time.parse('1/11/1906'), meta_info: { profession: 'Scientist' })
persin.valid?       # => false
persin.errors       # => [{name: "Albert Einstein is dead."}]

Finding

Find by id

person = Person.find(1)

Find an array of people

# returns an array of people
people = Person.find([1, 2])

Find the last people

# Finds the last person created
people = People.last

# Finds the last 10 people created 
people = People.last(10)

# Find 10 people, offset from the end of the id index by 30
people = People.last(10, 30)

Find the first people

# Finds the first person created
people = People.first

# Finds the first 10 people created 
people = People.first(10)

# Find 10 people offset from the beginning of the id index by 30
people = People.first(10, 30)

Find all of the people. WARNING: If you have large data sets, you should use find_in_batches instead.

people = Person.all

Find in batches

Works just like the ActiveRecord find_in_batches. The most performant way to iterate over large data sets

# Supports options 
# `batch_size` the amount of records to find in each batch. Default is `500`
# `offset` offset from the begining of the `id` index

People.find_in_batches do |people|
  people.each do |person|
    # do something with a person
  end
end

Deleting

Deletes all the persisted attributes from redis.

person = Person.find(1)
person.delete       # => true

A soft delete feature is built into RedisAssist. Simply add a deleted_at attribute to your model.

attr_persist :deleted_at, as: :time 

You can fetch soft deleted records by setting a deleted property when calling #find

Person.find(1, deleted: true)

Callbacks

RedisAssist supports callbacks through a Rails like interface.

before_save :titleize_blog_title
after_create :send_to_real_time_sphinx_index
after_update :update_in_realtime_sphinx_index

after_delete do |record|
  record.cleanup!
end

def titleize_blog_title 
  blog_title.titleize!
end

def send_to_realtime_sphinx_index
  ...
end

def update_in_realtime_sphinx_index
  ...
end

Relationships

Experimental support for has_many and belongs_to relationships.

class Person < RedisAssist::Base
  attr_persist  :name
  has_many      :pets
end
        
class Pet < RedisAssist::Base
  attr_persist  :name
  belongs_to    :person
end

person = Person.create(name: 'Tyler Love')
person.add_pet Pet.new('Hubble Love')
person.add_pet Pet.new('Oliver Love')
person.save

person.pet_ids      # => [1,2]
person.pets         # => [..pets..]

pet = Pet.find(1) 
pet.person

Helpful methods

The Redis client used for the class

client = People.redis

Rename an attribute

RedisAssist::Utils.rename_attribute(model: Person, from: :name, to: :full_name)

Transforms

Since Redis only supports string values RedisAssist provides an interface for serialization in and out of Redis.

Currently RedisAssist natively supports the following types.

• String default
• Boolean
• Float
• Integer
• JSON
• Time
• list native redis list data type
• hash native redis hash data type

RedisAssist also provides an elegant API for defining custom transforms.

# Serialize/Deserialize objects with the MessagePack gem
class MessagePackTransform < RedisAssist::Transform
  def self.to(val)
    val.to_msgpack
  end

  def self.from(val)
    MessagePack.unpack(val) 
  end
end

To use the MessagePackTransform we just defined

attr_persist :really_long_biography, as: :message_pack      

Useful Info

RedisAssist takes advantage of redis hashes to store each persisted attribute. Using the Person module as an example, the fields will be stored as a Redis Hash with the key person:[id]:attributes. Several other design approaches were considered. This method was selected because 1) it keeps the underlying data structures flat and normalized in Redis 2) Offers Redis Hash performance benefits, as outlined here: http://redis.io/topics/memory-optimization

Hundreds of millions of RedisAssist creates, updates, finds, and saves are called on bustle.com every month.

In the works

• Refactor an internal API to add more robust support for native Redis data types. Currently there is basic support for lists and hashes. We intend to add advanced support for all Redis data types.
• Refactoring relationship support. RedisAssist relations are not an attempt to recreate SQL joins. The goal is to provide a convenient API for ordering, sorting, iterating over your data sets. It will never do everything a SQL JOIN will do, but it introduces many other practical ways of organizing, reading, and writing your data sets.
• Cleanup and 1.0
• Utilities to help with data migrations.
• redis_assist_index a seperate gem that adds native support for storing your redis models in Sphinx real-time indexes. Full super advanced full-text search, facets, sorting, etc. Hit me up at product@bustle.com if you're interested.

Requirements

redis-rb

Configuration

You can configure RedisAssist with your own redis client

RedisAssist::Config.redis = Redis.new([connection settings...])