AASM Diagram

AASM Diagram creates diagrams for AASM state machines. To take an example from the AASM Readme:

require 'aasm-diagram'

class Job
  include AASM

  aasm do
    state :sleeping, :initial => true
    state :running, :cleaning

    event :run do
      transitions :from => :sleeping, :to => :running
    end

    event :clean do
      transitions :from => :running, :to => :cleaning
    end

    event :sleep do
      transitions :from => [:running, :cleaning], :to => :sleeping
    end
  end
end

job = Job.new

AASMDiagram::Diagram.new(job.aasm, 'docs/job.png')

Generates the following diagram:

Installation

• Install Graphviz (see the rails-erd guide for more details). If you use Homebrew try brew install graphviz.
• Add gem 'aasm-diagram', require: false, group: :development to your Gemfile and run bundle.

Integration

The gem exposes the generate Rake task, that can be used to generate the diagrams of state machines into
PNG images. The generate task accepts two parameters:

• the name of the model, in underscored format, will be CamelCased by the task
• the name of the state machine, for models with multiple AASMs; this argument is optional

The task will output the PNG image by default to the /tmp folder; but can be configured via the
AASM_DIAGRAM_OUTPUT_DIR environment variable to write the files to another folder.

The filenames are generated based on the parameters as follows model_name-state_machine_name.png.
If no state machine name is provided, the task will use default for the file name.

# for the Order model and the :dropoff state machine
rake aasm-diagram:generate[order,dropoff] # -> tmp/order-dropoff.png

# for the Invoice model and the "default" state machine
rake aasm-diagram:generate[invoice] # -> tmp/invoice-default.png

# with custom output directory
AASM_DIAGRAM_OUTPUT_DIR=docs rake aasm-diagram:generate[invoice] # -> docs/invoice-default.png

Rails

Once installed, the gem automatically integrates with Rails via Railties and exposes the task automatically.

rails aasm-diagram:generate[my_model,my_state_machine]

If the model contains only one state machine, or you just want to generate for the “default” one
you can skip the state machine name parameter.

rails aasm-diagram:generate[my_model]

Plain Ruby

For plain Ruby projects the gem includes a Rakefile that can be loaded in your project’s Rakefile,
using source code along the lines of:

# in Rakefile

require 'aasm-diagram'

spec = Gem::Specification.find_by_name 'aasm-diagram'
rakefile = "#{spec.gem_dir}/lib/aasm_diagram/Rakefile"
load rakefile

More Examples

Guards

class Cleaner
  include AASM

  aasm do
    state :idle, :initial => true
    state :cleaning

    event :clean do
      transitions :from => :idle, :to => :cleaning, :guard => :cleaning_needed?
    end

    event :clean_if_needed do
      transitions :from => :idle, :to => :cleaning do
        guard do
          cleaning_needed?
        end
      end
      transitions :from => :idle, :to => :idle
    end

    event :clean_if_dirty do
      transitions :from => :idle, :to => :cleaning, :guard => :if_dirty?
    end
  end

  def cleaning_needed?
    false
  end

  def if_dirty?(status)
    status == :dirty
  end
end

cleaner = Cleaner.new
AASMDiagram::Diagram.new(job.aasm, '../docs/guard-cleaner.png')

Multiple state machines per class

class SimpleMultipleExample
  include AASM
  aasm(:move) do
    state :standing, :initial => true
    state :walking
    state :running

    event :walk do
      transitions :from => :standing, :to => :walking
    end
    event :run do
      transitions :from => [:standing, :walking], :to => :running
    end
    event :hold do
      transitions :from => [:walking, :running], :to => :standing
    end
  end

  aasm(:work) do
    state :sleeping, :initial => true
    state :processing

    event :start do
      transitions :from => :sleeping, :to => :processing
    end
    event :stop do
      transitions :from => :processing, :to => :sleeping
    end
  end
end

simple = SimpleMultipleExample.new
AASMDiagram::Diagram.new(simple.aasm(:move), 'docs/multiple-state-machines-1.png')
AASMDiagram::Diagram.new(simple.aasm(:work), 'docs/multiple-state-machines-2.png')

Generates two images:

Notes

AASM Diagram is heavily inspired by rails-erd.

License

The gem is available as open source under the terms of the MIT License.