Herd

Organize ActiveRecord collection functionality into manageable classes.

Requirements

Ruby >= 1.9.2
Rails >= 3.0.0

What is Herd?

As models grow in size and complexity, it can be challenging to keep track of which class methods are for collections and which are not. Throw validations, associations, and scopes into the mix, and the model can become unwieldy to manage.

Herd provides a way to organize collection related functionality into separate, manageable classes.

Take the following ActiveRecord class for example:

class Movie < ActiveRecord::Base
  scope :recent, where('released_at > ?', 6.months.ago)
  scope :profitable, where('gross > budget')

  def self.filter_by_title(title)
    where('title LIKE ?', "%#{title}%")
  end

  def release_year
    released_at.year
  end

  def profitable?
    gross > budget
  end
end

Using Herd, you can define a separate class to declare collection concerns:

class Movie < ActiveRecord::Base
  herded_by Movies

  def release_year
    released_at.year
  end

  def profitable?
    gross > budget
  end
end

class Movies < Herd::Base
  model Movie # optional

  scope :recent, where('released_at > ?', 6.months.ago)
  scope :profitable, where('gross > budget')

  def self.filter_by_title(title)
    where('title LIKE ?', "%#{title}%")
  end
end

Installation

Add this line to your application's Gemfile:

gem 'herd'

And then execute:

$ bundle

Or install it yourself as:

$ gem install herd

Usage Example

Using Herd is as easy as inheriting from Herd::Base. Declaring the model is optional if it can be inferred by the ActiveRecord class name.

class Movie < ActiveRecord::Base
  herded_by Movies

  has_and_belongs_to_many :directors
  has_many :characters, :dependent => :destroy
end

class Movies < Herd::Base
  model Movie # optional

  scope :failures, where("revenue < '10000000'")

  def self.directed_by(director)
    where(directors: {name: director}).joins(:directors)
  end
end

Then you can use the collection methods as if they were defined in the model class:

Movie.where('released_at < 2012-06-01').failures

Director.first.movies.failures

You can also use the Herd classes directly:

Movies.failures

Contributing