Hashifiable

With Hashifiable you can specify a line with the methods that will be called to create a hash representation of your object. Simple and straightforward.

How it works

require 'hashifiable'

class User < Struct.new(:id, :name, :state, :private_data, :more_private_data)
  extend Hashifiable
  hashify :id, :name, :state
end

user = User.new(1, 'pote', 'active', 'real credit card number', 'super secret token')

user.to_h     # Yes, #to_hash works too, but be good and use to_h. :)
#=> {:id=>1, :name=>"pote", :state=>"active"}

As simple as that, I find most gems with similar functionality to simply do too much, Hashifiable provides a minimum interface to solve the problem of object representation (mostly to be used in APIs) without too much fuzz.

Passing Procs and lambdas

You can also declare a Proc or a lambda instead of just specifying a method name.

class User < ActiveRecord::Base

  has_many :hobbies

  extend Hashifiable
  hashify :id,
          :name,
          :hobbies => Proc.new { hobbies.map(:&to_hash) },
          :right_now => lambda { Time.now }
end

Complex structures

If you want to define whatever complex structure to be included you can simply define a method in your object that returns said structure and include it by name in the hashify statement. Like so:

class User < ActiveRecord::Base
  has_many :activity_logs

  extend Hashifiable
  hashify :id, :name, :activity

  def activity
  {
    logs: self.activity_logs.map(&:to_h),
    appointments: self.appointments.map(&:to_h),
    random: {
      i_am_a_key: 'And I am a value',
      bacon:  'cats'
    }
  }
  end
end

Installation

$ gem install hashifiable

Development setup

$ bundle install
$ rspec

Thanks

To @soveran for an alternative and prettier implementation than the one I had came up with originally.
To @tizoc for great constructive criticism and pointing me towards instance_exec, of which I didn't know about. :)
To all contributors