Module: Renalware::ExplicitStateModel

Extended by:

ActiveSupport::Concern

Included in:

HD::Session, Letters::Letter

Defined in:

app/models/concerns/renalware/explicit_state_model.rb

Overview

Enables Explicit State Models with ActiveRecord in contrast to the State pattern or Finite State Machines (FSM). For more information: medium.com/@martinezdelariva/explicit-state-modeling-f6e534c33508#.ljvhnkz01

Example

class Letter < ActiveRecord
  include ExplicitStateModel
  # define the states you would like
  has_states :draft, :approved
end

Calling the ‘has_states` macro will:

• define scopes for each state; e.g. ‘Letter.draft`, `Letter.approved`

• add a state attribute; e.g. ‘Letter::Draft.state # => “draft”`

Create subclasses representing those states, this uses ActiveRecord’s STI implementation.

class Letter::Draft < Letter
  def approve!
    becomes!(Approved)
  end
end

class Letter::Approved < Letter
end

You are responsible for managing state transitions using ActiveRecord’s ‘becomes` class method:

Letter::Draft.create!
draft_letter = Letter.draft.first!
draft_letter.state # => "draft"
draft_letter.draft? # => true
approved_letter = draft_letter.approve!
approved_letter.save!
approved_letter.state # => "approved"

Defined Under Namespace

Modules: ClassMethods