FrozenRecord

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ActiveRecord-like interface for read only access to static data files.

Installation

Add this line to your application's Gemfile:

gem 'frozen_record'

And then execute:

$ bundle

Or install it yourself as:

$ gem install frozen_record

Models definition

Just like with ActiveRecord, your models need to inherits from FrozenRecord::Base:

class Country < FrozenRecord::Base
end

But you also have to specify in which directory your data files are located. You can either do it globaly

FrozenRecord::Base.base_path = '/path/to/some/directory'

Or per model:

class Country < FrozenRecord::Base
  self.base_path = '/path/to/some/directory'
end

You can also specify a custom backend. Backends are classes that know how to load records from a static file. By default FrozenRecord expects an YAML file, but this option can be changed per model:

class Country < FrozenRecord::Base
  self.backend = FrozenRecord::Backends::Yaml
end

Custom backends

A valid backend must implement two class methods, filename and load.

class MyCustomBackend
  class << self
    def filename(model_name)
      # Returns the file name as a String
    end

    def load(file_path)
      # Reads file and returns records as an Array of Hash objects
    end
  end
end

Query interface

FrozenRecord aim to replicate only modern ActiveRecord querying interface, and only the non "string typed" ones.

e.g

# Supported query interfaces
Country.
  where(region: 'Europe').
  where.not(language: 'English').
  order(id: :desc).
  limit(10).
  offset(2).
  pluck(:name)

# Non supported query interfaces
Country.
  where('region = "Europe" AND language != "English"').
  order('id DESC')

Scopes

While the scope :symbol, lambda syntax is not supported, the class methods way is:

class Country
  def self.republics
    where(king: nil)
  end

  def self.part_of_nato
    where(nato: true)
  end
end

Country.republics.part_of_nato.order(id: :desc)

Supported query methods

  • where
  • where.not
  • order
  • limit
  • offset

Supported finder methods

  • find
  • first
  • last
  • to_a
  • exists?

Supported calculation methods

  • count
  • pluck
  • ids
  • minimum
  • maximum
  • sum
  • average

Configuration

Reloading

By default the YAML files are parsed once and then cached in memory. But in development you might want changes to be reflected without having to restart your application.

For such cases you can set auto_reloading to true either globally or on a model basis:

FrozenRecord::Base.auto_reloading = true # Activate reloading for all models
Country.auto_reloading # Activate reloading for `Country` only

Contributors

FrozenRecord is a from scratch reimplementation of a Shopify project from 2007 named YamlRecord. So thanks to: