La Maquina

Model graph traversal

Installation

Add this line to your application's Gemfile:

gem 'la_maquina'

And then execute:

$ bundle

Or install it yourself as:

$ gem install la_maquina

Usage

Pistons

Once the Engine is called it fires the Pistons, the behavior of which is entirely up to you.

So, let's say, we have a couple objects that look like:

class DannyTrejo < ActiveRecord::Base
  has_many :machetes

  searchable do 
    double  :machete_sharpness, multiple: true do
      machetes.map(&:sharpness)
    end
  end
end

class Machete < ActiveRecord::Base
  belongs_to :danny_trejo

  include LaMaquina::Notifier
  notifies_about :danny_trejo
end

and we want to let DannyTrejo know when his Machete has been updated so that we can reindex him.

Machete is set up to fire on update, so we'll set up a listener Piston that looks like this:

class SunspotPiston < LaMaquina::Piston::Base
  class << self
    def fire!( notified_class, id, notifier_class = "" )
      indexed_class(notified_class).find(id).index!
    end

    private

    def indexed_class(klass)
      {"danny_trejo" => DannyTrejo}[klass] or raise "can't index class #{klass}!"
    end
  end
end

Which finds the klass, does a find on it and fires off Sunspot index!

Setup

The setup is pretty straightforward: you do all the setting up in config/initializers/la_maquina.rb.

The 3 things you have to do are: set up the pistons(if they need configuring), install them, and configure the error_handler. For example, if you're using the CachePiston and need to set up Redis, here's how your la_maquina.rb will look

LaMaquina::Piston::CachePiston.redis = Redis::Namespace.new(:cache_piston, redis: Redis.new)
LaMaquina::Engine.install LaMaquina::Piston::CachePiston, TestPiston
LaMaquina.error_notifier = LaMaquina::ErrorNotifier::HoneybadgerNotifier

ErrorNotifier

LaMaquina by default comes with an ErrorNotifier::Base that will explode in a very unhelpful manner. To override it, you need to change it in the config above and roll a new ErrorNotifier that responds to notify(error, details). For example, if you're using Honeybadger, you can use the included `LaMaquina::ErrorNotifiers::HoneybadgerNotifier, which looks like:

class HoneybadgerNotifier < LaMaquina::ErrorNotifier::Base
  self.notify(error = nil, details = {})
    Honeybadger.notify( :error_class => "CacheMachineError: #{error.class.name}",
                        :error_message => error.message,
                        :parameters => details
                      )
  end
end

If you don't care about your exceptions and want to ignore them, there's a notifier you can use, SilentNotifier, making that last line in your config/initializers/la_maquina.rb be

LaMaquina::Cinegual.error_notifier = LaMaquina::ErrorNotifier::SilentNotifier

Contributing

1. Fork it ( https://github.com/[my-github-username]/la_maquina/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request