aasm

AASM - Ruby state machines

AASM - State machines for Ruby classes (plain Ruby, ActiveRecord, Mongoid, NoBrainer, Dynamoid)
Under MIT License
By aasm

hacktoberfest ruby state-machine aasm transition activerecord mongoid rails

AASM - Ruby state machines


Index

This package contains AASM, a library for adding finite state machines to Ruby classes.


AASM started as the acts_as_state_machine plugin but has evolved into a more generic library
that no longer targets only ActiveRecord models. It currently provides adapters for many
ORMs but it can be used for any Ruby class, no matter what parent class it has (if any).


Upgrade from version 3 to 4

Take a look at the README_FROM_VERSION_3_TO_4 for details how to switch from version 3.x to 4.0 of AASM.


Usage

Adding a state machine is as simple as including the AASM module and start defining
states and events together with their transitions:


```ruby
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
```


This provides you with a couple of public methods for instances of the class Job:


ruby
job = Job.new
job.sleeping? # => true
job.may_run? # => true
job.run
job.running? # => true
job.sleeping? # => false
job.may_run? # => false
job.run # => raises AASM::InvalidTransition


If you don't like exceptions and prefer a simple true or false as response, tell
AASM not to be whiny:


```ruby
class Job
...
aasm whiny_transitions: false do
...
end
end


job.running? # => true
job.may_run? # => false
job.run # => false
```


When firing an event, you can pass a block to the method, it will be called only if
the transition succeeds :


ruby
job.run do
job.user.notify_job_ran # Will be called if job.may_run? is true
end


Callbacks

You can define a number of callbacks for your events, transitions and states. These methods, Procs or classes will be
called when certain criteria are met, like entering a particular state:


```ruby
class Job
include AASM


aasm do
state :sleeping, initial: true, before_enter: :do_something
state :running, before_enter: Proc.new { do_something && notify_somebody }
state :finished


after_all_transitions :log_status_change

event :run, after: :notify_somebody do
before do
log('Preparing to run')
end

transitions from: :sleeping, to: :running, after: Proc.new {|*args| set_process(*args) }
transitions from: :running, to: :finished, after: LogRunTime
end

event :sleep do
after do
...
end
error do |e|
...
end
transitions from: :running, to: :sleeping
end


end


def log_status_change
puts "changing from #{aasm.from_state} to #{aasm.to_state} (event: #{aasm.current_event})"
end


def set_process(name)
...
end


def do_something
...
end


def notify_somebody
...
end


end


class LogRunTime
def call
log "Job was running for X seconds"
end
end
```


In this case do_something is called before actually entering the state sleeping,
while notify_somebody is called after the transition run (from sleeping to running)
is finished.


AASM will also initialize LogRunTime and run the call method for you after the transition from running to finished in the example above. You can pass arguments to the class by defining an initialize method on it, like this:


Note that Procs are executed in the context of a record, it means that you don't need to expect the record as an argument, just call the methods you need.


```ruby
class LogRunTime
# optional args parameter can be omitted, but if you define initialize
# you must accept the model instance as the first parameter to it.
def initialize(job, args = {})
@job = job
end


def call
log "Job was running for #{@job.run_time} seconds"
end
end
```


Parameters

You can pass parameters to events:


ruby
job = Job.new
job.run(:defragmentation)


All guards and after callbacks will receive these parameters. In this case set_process would be called with
:defragmentation argument.


If the first argument to the event is a state (e.g. :running or :finished), the first argument is consumed and
the state machine will attempt to transition to that state. Add comma separated parameter for gaurds and callbacks


ruby
job = Job.new
job.run(:running, :defragmentation)

In this case set_process won't be called, job will transition to running state and callback will receive
:defragmentation as parameter


Error Handling

In case of an error during the event processing the error is rescued and passed to :error
callback, which can handle it or re-raise it for further propagation.


Also, you can define a method that will be called if any event fails:


ruby
def aasm_event_failed(event_name, old_state_name)
# use custom exception/messages, report metrics, etc
end


During the transition's :after callback (and reliably only then, or in the global
after_all_transitions callback) you can access the originating state (the from-state)
and the target state (the to state), like this:


ruby
def set_process(name)
logger.info "from #{aasm.from_state} to #{aasm.to_state}"
end


Lifecycle

Here you can see a list of all possible callbacks, together with their order of calling:


ruby
begin
event before_all_events
event before
event guards
transition guards
old_state before_exit
old_state exit
after_all_transitions
transition after
new_state before_enter
new_state enter
...update state...
event before_success # if persist successful
transition success # if persist successful, database update not guaranteed
event success # if persist successful, database update not guaranteed
old_state after_exit
new_state after_enter
event after
event after_all_events
rescue
event error
event error_on_all_events
ensure
event ensure
event ensure_on_all_events
end


Use event's after_commit callback if it should be fired after database update.


The current event triggered

While running the callbacks you can easily retrieve the name of the event triggered
by using aasm.current_event:


ruby
# taken the example callback from above
def do_something
puts "triggered #{aasm.current_event}"
end


and then


```ruby
job = Job.new


# without bang
job.sleep # => triggered :sleep


# with bang
job.sleep! # => triggered :sleep!
```


Guards

Let's assume you want to allow particular transitions only if a defined condition is
given. For this you can set up a guard per transition, which will run before actually
running the transition. If the guard returns false the transition will be
denied (raising AASM::InvalidTransition or returning false itself):


```ruby
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


job = Cleaner.new
job.may_clean? # => false
job.clean # => raises AASM::InvalidTransition
job.may_clean_if_needed? # => true
job.clean_if_needed! # idle


job.clean_if_dirty(:clean) # => false
job.clean_if_dirty(:dirty) # => true
```


You can even provide a number of guards, which all have to succeed to proceed


```ruby
def walked_the_dog?; ...; end


event :sleep do
transitions from: :running, to: :sleeping, guards: [:cleaning_needed?, :walked_the_dog?]
end

```


If you want to provide guards for all transitions within an event, you can use event guards


ruby
event :sleep, guards: [:walked_the_dog?] do
transitions from: :running, to: :sleeping, guards: [:cleaning_needed?]
transitions from: :cleaning, to: :sleeping
end


If you prefer a more Ruby-like guard syntax, you can use if and unless as well:


```ruby
event :clean do
transitions from: :running, to: :cleaning, if: :cleaning_needed?
end


event :sleep do
transitions from: :running, to: :sleeping, unless: :cleaning_needed?
end

end
```


You can invoke a Class instead a method since this Class responds to call


ruby
event :sleep do
transitions from: :running, to: :sleeping, guards: Dog
end

ruby
class Dog
def call
cleaning_needed? && walked?
end
...
end


Transitions

In the event of having multiple transitions for an event, the first transition that successfully completes will stop other transitions in the same event from being processed.


```ruby
require 'aasm'


class Job
include AASM


aasm do
state :stage1, initial: true
state :stage2
state :stage3
state :completed


event :stage1_completed do
transitions from: :stage1, to: :stage3, guard: :stage2_completed?
transitions from: :stage1, to: :stage2
end

end


def stage2_completed?
true
end
end


job = Job.new
job.stage1_completed
job.aasm.current_state # stage3
```


You can define transition from any defined state by omitting from:


ruby
event :abort do
transitions to: :aborted
end


Display name for state

You can define display name for state using :display option


```ruby
class Job
include AASM


aasm do
state :stage1, initial: true, display: 'First Stage'
state :stage2
state :stage3
end
end


job = Job.new
job.aasm.human_state


```


Multiple state machines per class

Multiple state machines per class are supported. Be aware though that AASM has been
built with one state machine per class in mind. Nonetheless, here's how to do it (see below). Please note that you will need to specify database columns for where your pertinent states will be stored - we have specified two columns move_state and work_state in the example below. See the Column name & migration section for further info.


```ruby
class SimpleMultipleExample
include AASM
aasm(:move, column: 'move_state') 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, column: 'work_state') 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


simple.aasm(:move).current_state


=> :standing

simple.aasm(:work).current_state


=> :sleeping

simple.start
simple.aasm(:move).current_state


=> :standing

simple.aasm(:work).current_state


=> :processing

```


Handling naming conflicts between multiple state machines

AASM doesn't prohibit to define the same event in more than one state
machine. If no namespace is provided, the latest definition "wins" and
overrides previous definitions. Nonetheless, a warning is issued:
SimpleMultipleExample: overriding method 'run'!.


Alternatively, you can provide a namespace for each state machine:


```ruby
class NamespacedMultipleExample
include AASM
aasm(:status) do
state :unapproved, initial: true
state :approved


event :approve do
transitions from: :unapproved, to: :approved
end

event :unapprove do
transitions from: :approved, to: :unapproved
end


end


aasm(:review_status, namespace: :review) do
state :unapproved, initial: true
state :approved


event :approve do
transitions from: :unapproved, to: :approved
end

event :unapprove do
transitions from: :approved, to: :unapproved
end


end
end


namespaced = NamespacedMultipleExample.new


namespaced.aasm(:status).current_state


=> :unapproved

namespaced.aasm(:review_status).current_state


=> :unapproved

namespaced.approve_review
namespaced.aasm(:review_status).current_state


=> :approved

```


All AASM class- and instance-level aasm methods accept a state machine selector.
So, for example, to use inspection on a class level, you have to use


```ruby
SimpleMultipleExample.aasm(:move).states.map(&:name)


=> [:standing, :walking, :running]

```


Binding event

Allow an event to be bound to another
```ruby
class Example
include AASM


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


aasm(:question) do
state :answered, initial: true
state :asked


event :ask, binding_event: :start do
transitions from: :answered, to: :asked
end
event :answer, binding_event: :stop do
transitions from: :asked, to: :answered
end

end
end


example = Example.new
example.aasm(:work).current_state #=> :sleeping
example.aasm(:question).current_state #=> :answered
example.ask
example.aasm(:work).current_state #=> :processing
example.aasm(:question).current_state #=> :asked
```


Auto-generated Status Constants

AASM automatically generates constants
for each status so you don't have to explicitly define them.


```ruby
class Foo
include AASM


aasm do
state :initialized
state :calculated
state :finalized
end
end



Foo::STATE_INITIALIZED



=> :initialized

Foo::STATE_CALCULATED



=> :calculated

```


Extending AASM

AASM allows you to easily extend AASM::Base for your own application purposes.


Let's suppose we have common logic across many AASM models. We can embody this logic in a sub-class of AASM::Base.


```ruby
class CustomAASMBase < AASM::Base
# A custom transiton that we want available across many AASM models.
def count_transitions!
klass.class_eval do
aasm with_klass: CustomAASMBase do
after_all_transitions :increment_transition_count
end
end
end


# A custom annotation that we want available across many AASM models.
def requires_guards!
klass.class_eval do
attr_reader :authorizable_called,
:transition_count,
:fillable_called


  def authorizable?
@authorizable_called = true
end

def fillable?
@fillable_called = true
end

def increment_transition_count
@transition_count ||= 0
@transition_count += 1
end
end


end
end
```


When we declare our model that has an AASM state machine, we simply declare the AASM block with a :with_klass key to our own class.


```ruby
class SimpleCustomExample
include AASM


# Let's build an AASM state machine with our custom class.
aasm with_klass: CustomAASMBase do
requires_guards!
count_transitions!


state :initialised, initial: true
state :filled_out
state :authorised

event :fill_out do
transitions from: :initialised, to: :filled_out, guard: :fillable?
end
event :authorise do
transitions from: :filled_out, to: :authorised, guard: :authorizable?
end


end
end
```


ActiveRecord

AASM comes with support for ActiveRecord and allows automatic persisting of the object's
state in the database.


Add gem 'after_commit_everywhere', '~> 1.0' to your Gemfile.


```ruby
class Job < ActiveRecord::Base
include AASM


aasm do # default column: aasm_state
state :sleeping, initial: true
state :running


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

event :sleep do
transitions from: :running, to: :sleeping
end


end


end
```


Bang events

You can tell AASM to auto-save the object or leave it unsaved


```ruby
job = Job.new
job.run # not saved
job.run! # saved


or

job.aasm.fire(:run) # not saved
job.aasm.fire!(:run) # saved
```


Saving includes running all validations on the Job class. If
whiny_persistence flag is set to true, exception is raised in case of
failure. If whiny_persistence flag is set to false, methods with a bang return
true if the state transition is successful or false if an error occurs.


If you want make sure the state gets saved without running validations (and
thereby maybe persisting an invalid object state), simply tell AASM to skip the
validations. Be aware that when skipping validations, only the state column will
be updated in the database (just like ActiveRecord update_column is working).


```ruby
class Job < ActiveRecord::Base
include AASM


aasm skip_validation_on_save: true do
state :sleeping, initial: true
state :running


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

event :sleep do
transitions from: :running, to: :sleeping
end


end


end
```


Also You can skip the validation at instance level with some_event_name_without_validation! method.
With this you have the flexibility of having validation for all your transitions by default and then skip it wherever required.
Please note that only state column will be updated as mentioned in the above example.


ruby
job.run_without_validation!


If you want to make sure that the AASM column for storing the state is not directly assigned,
configure AASM to not allow direct assignment, like this:


```ruby
class Job < ActiveRecord::Base
include AASM


aasm no_direct_assignment: true do
state :sleeping, initial: true
state :running


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

end


end
```


resulting in this:


ruby
job = Job.create
job.aasm_state # => 'sleeping'
job.aasm_state = :running # => raises AASM::NoDirectAssignmentError
job.aasm_state # => 'sleeping'


Timestamps

You can tell AASM to try to write a timestamp whenever a new state is entered.
If timestamps: true is set, AASM will look for a field named like the new state plus _at and try to fill it:


```ruby
class Job < ActiveRecord::Base
include AASM


aasm timestamps: true do
state :sleeping, initial: true
state :running


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

end
end
```


resulting in this:


ruby
job = Job.create
job.running_at # => nil
job.run!
job.running_at # => 2020-02-20 20:00:00


Missing timestamp fields are silently ignored, so it is not necessary to have setters (such as ActiveRecord columns) for all states when using this option.


ActiveRecord enums

You can use
enumerations
in Rails 4.1+ for your state column:


```ruby
class Job < ActiveRecord::Base
include AASM


enum state: {
sleeping: 5,
running: 99
}


aasm column: :state, enum: true do
state :sleeping, initial: true
state :running
end
end
```


You can explicitly pass the name of the method which provides access
to the enumeration mapping as a value of enum, or you can simply
set it to true. In the latter case AASM will try to use
pluralized column name to access possible enum states.


Furthermore, if your column has integer type (which is normally the
case when you're working with Rails enums), you can omit :enum
setting --- AASM auto-detects this situation and enabled enum
support. If anything goes wrong, you can disable enum functionality
and fall back to the default behavior by setting :enum
to false.


Sequel

AASM also supports Sequel besides ActiveRecord, and Mongoid.


```ruby
class Job < Sequel::Model
include AASM


aasm do # default column: aasm_state
...
end
end
```


However it's not yet as feature complete as ActiveRecord. For example, there are
scopes defined yet. See Automatic Scopes.


Dynamoid

Since version 4.8.0 AASM also supports Dynamoid as
persistence ORM.


Mongoid

AASM also supports persistence to Mongodb if you're using Mongoid. Make sure
to include Mongoid::Document before you include AASM.


ruby
class Job
include Mongoid::Document
include AASM
field :aasm_state
aasm do
...
end
end


NoBrainer

AASM also supports persistence to RethinkDB
if you're using Nobrainer.
Make sure to include NoBrainer::Document before you include AASM.


ruby
class Job
include NoBrainer::Document
include AASM
field :aasm_state
aasm do
...
end
end


Redis

AASM also supports persistence in Redis via
Redis::Objects.
Make sure to include Redis::Objects before you include AASM. Note that non-bang
events will work as bang events, persisting the changes on every call.


```ruby
class User
include Redis::Objects
include AASM


aasm do
end
end
```


Automatic Scopes

AASM will automatically create scope methods for each state in the model.


```ruby
class Job < ActiveRecord::Base
include AASM


aasm do
state :sleeping, initial: true
state :running
state :cleaning
end


def self.sleeping
"This method name is already in use"
end
end
```


```ruby
class JobsController < ApplicationController
def index
@running_jobs = Job.running
@recent_cleaning_jobs = Job.cleaning.where('created_at >= ?', 3.days.ago)


# @sleeping_jobs = Job.sleeping   #=> "This method name is already in use"

end
end
```


If you don't need scopes (or simply don't want them), disable their creation when
defining the AASM states, like this:


```ruby
class Job < ActiveRecord::Base
include AASM


aasm create_scopes: false do
state :sleeping, initial: true
state :running
state :cleaning
end
end
```


Transaction support

Since version 3.0.13 AASM supports ActiveRecord transactions. So whenever a transition
callback or the state update fails, all changes to any database record are rolled back.
Mongodb does not support transactions.


There are currently 3 transactional callbacks that can be handled on the event, and 2 transactional callbacks for all events.


ruby
event before_all_transactions
event before_transaction
event aasm_fire_event (within transaction)
event after_commit (if event successful)
event after_transaction
event after_all_transactions


If you want to make sure a depending action happens only after the transaction is committed,
use the after_commit callback along with the auto-save (bang) methods, like this:


```ruby
class Job < ActiveRecord::Base
include AASM


aasm do
state :sleeping, initial: true
state :running


event :run, after_commit: :notify_about_running_job do
transitions from: :sleeping, to: :running
end

end


def notify_about_running_job
...
end
end


job = Job.where(state: 'sleeping').first!
job.run! # Saves the model and triggers the after_commit callback
```


Note that the following will not run the after_commit callbacks because
the auto-save method is not used:


ruby
job = Job.where(state: 'sleeping').first!
job.run
job.save! #notify_about_running_job is not run


Please note that :after_commit AASM callbacks behaves around custom implementation
of transaction pattern rather than a real-life DB transaction. This fact still causes
the race conditions and redundant callback calls within nested transaction. In order
to fix that it's highly recommended to add gem 'after_commit_everywhere', '~> 1.0'
to your Gemfile.


If you want to encapsulate state changes within an own transaction, the behavior
of this nested transaction might be confusing. Take a look at
ActiveRecord Nested Transactions
if you want to know more about this. Nevertheless, AASM by default requires a new transaction
transaction(requires_new: true). You can override this behavior by changing
the configuration


```ruby
class Job < ActiveRecord::Base
include AASM


aasm requires_new_transaction: false do
...
end


...
end
```


which then leads to transaction(requires_new: false), the Rails default.


Additionally, if you do not want any of your ActiveRecord actions to be
wrapped in a transaction, you can specify the use_transactions flag. This can
be useful if you want want to persist things to the database that happen as a
result of a transaction or callback, even when some error occurs. The
use_transactions flag is true by default.


```ruby
class Job < ActiveRecord::Base
include AASM


aasm use_transactions: false do
...
end


...
end
```


Pessimistic Locking

AASM supports ActiveRecord pessimistic locking via with_lock for database persistence layers.


| Option | Purpose |
| ------ | ------- |
| false (default) | No lock is obtained | |
| true | Obtain a blocking pessimistic lock e.g. FOR UPDATE |
| String | Obtain a lock based on the SQL string e.g. FOR UPDATE NOWAIT |


```ruby
class Job < ActiveRecord::Base
include AASM


aasm requires_lock: true do
...
end


...
end
```


```ruby
class Job < ActiveRecord::Base
include AASM


aasm requires_lock: 'FOR UPDATE NOWAIT' do
...
end


...
end
```


Column name & migration

As a default AASM uses the column aasm_state to store the states. You can override
this by defining your favorite column name, using :column like this:


```ruby
class Job < ActiveRecord::Base
include AASM


aasm column: :my_state do
...
end


aasm :another_state_machine, column: :second_state do
...
end
end
```


Whatever column name is used, make sure to add a migration to provide this column
(of type string).
Do not add default value for column at the database level. If you add default
value in database then AASM callbacks on the initial state will not be fired upon
instantiation of the model.


```ruby
class AddJobState < ActiveRecord::Migration
def self.up
add_column :jobs, :aasm_state, :string
end


def self.down
remove_column :jobs, :aasm_state
end
end
```


Log State Changes

Logging state change can be done using paper_trail gem


Example of implementation can be found here https://github.com/nitsujri/aasm-papertrail-example


Inspection

AASM supports query methods for states and events


Given the following Job class:


```ruby
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, guard: :cleaning_needed?
end

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


end


def cleaning_needed?
false
end
end
```


```ruby


show all states

Job.aasm.states.map(&:name)


=> [:sleeping, :running, :cleaning]

job = Job.new


show all permitted states (from initial state)

job.aasm.states(permitted: true).map(&:name)


=> [:running]
List all the permitted transitions(event and state pairs) from initial state

job.aasm.permitted_transitions


=> [{ :event => :run, :state => :running }]

job.run
job.aasm.states(permitted: true).map(&:name)


=> [:sleeping]
show all non permitted states

job.aasm.states(permitted: false).map(&:name)


=> [:cleaning]
show all possible (triggerable) events from the current state

job.aasm.events.map(&:name)


=> [:clean, :sleep]
show all permitted events

job.aasm.events(permitted: true).map(&:name)


=> [:sleep]
show all non permitted events

job.aasm.events(permitted: false).map(&:name)


=> [:clean]
show all possible events except a specific one

job.aasm.events(reject: :sleep).map(&:name)


=> [:clean]
list states for select

Job.aasm.states_for_select


=> [["Sleeping", "sleeping"], ["Running", "running"], ["Cleaning", "cleaning"]]
show permitted states with guard parameter

job.aasm.states({permitted: true}, guard_parameter).map(&:name)
```


Warning output

Warnings are by default printed to STDERR. If you want to log those warnings to another output,
use


```ruby
class Job
include AASM


aasm logger: Rails.logger do
...
end
end
```


You can hide warnings by setting AASM::Configuration.hide_warnings = true


RubyMotion support

Now supports CodeDataQuery !
However I'm still in the process of submitting my compatibility updates to their repository.
In the meantime you can use my fork, there may still be some minor issues but I intend to extensively use it myself, so fixes should come fast.


Warnings:
- Due to RubyMotion Proc's lack of 'source_location' method, it may be harder
to find out the origin of a "cannot transition from" error. I would recommend using
the 'instance method symbol / string' way whenever possible when defining guardians and callbacks.


Testing
RSpec

AASM provides some matchers for RSpec:
* transition_from,
* have_state, allow_event
* and allow_transition_to.


Installation Instructions:

Examples Of Usage in Rspec:

```ruby


classes with only the default state machine

job = Job.new
expect(job).to transition_from(:sleeping).to(:running).on_event(:run)
expect(job).not_to transition_from(:sleeping).to(:cleaning).on_event(:run)
expect(job).to have_state(:sleeping)
expect(job).not_to have_state(:running)
expect(job).to allow_event :run
expect(job).to_not allow_event :clean
expect(job).to allow_transition_to(:running)
expect(job).to_not allow_transition_to(:cleaning)


on_event also accept multiple arguments

expect(job).to transition_from(:sleeping).to(:running).on_event(:run, :defragmentation)


classes with multiple state machine

multiple = SimpleMultipleExample.new
expect(multiple).to transition_from(:standing).to(:walking).on_event(:walk).on(:move)
expect(multiple).to_not transition_from(:standing).to(:running).on_event(:walk).on(:move)
expect(multiple).to have_state(:standing).on(:move)
expect(multiple).not_to have_state(:walking).on(:move)
expect(multiple).to allow_event(:walk).on(:move)
expect(multiple).to_not allow_event(:hold).on(:move)
expect(multiple).to allow_transition_to(:walking).on(:move)
expect(multiple).to_not allow_transition_to(:running).on(:move)
expect(multiple).to transition_from(:sleeping).to(:processing).on_event(:start).on(:work)
expect(multiple).to_not transition_from(:sleeping).to(:sleeping).on_event(:start).on(:work)
expect(multiple).to have_state(:sleeping).on(:work)
expect(multiple).not_to have_state(:processing).on(:work)
expect(multiple).to allow_event(:start).on(:move)
expect(multiple).to_not allow_event(:stop).on(:move)
expect(multiple).to allow_transition_to(:processing).on(:move)
expect(multiple).to_not allow_transition_to(:sleeping).on(:move)


allow_event also accepts arguments

expect(job).to allow_event(:run).with(:defragmentation)


```


Minitest

AASM provides assertions and rspec-like expectations for Minitest.


Assertions

List of supported assertions: assert_have_state, refute_have_state, assert_transitions_from, refute_transitions_from, assert_event_allowed, refute_event_allowed, assert_transition_to_allowed, refute_transition_to_allowed.


Examples Of Usage (Minitest):

Add require 'aasm/minitest' to your test_helper.rb file and use them like this:


```ruby


classes with only the default state machine

job = Job.new
assert_transitions_from job, :sleeping, to: :running, on_event: :run
refute_transitions_from job, :sleeping, to: :cleaning, on_event: :run
assert_have_state job, :sleeping
refute_have_state job, :running
assert_event_allowed job, :run
refute_event_allowed job, :clean
assert_transition_to_allowed job, :running
refute_transition_to_allowed job, :cleaning


on_event also accept arguments

assert_transitions_from job, :sleeping, :defragmentation, to: :running, on_event: :run


classes with multiple state machine

multiple = SimpleMultipleExample.new
assert_transitions_from multiple, :standing, to: :walking, on_event: :walk, on: :move
refute_transitions_from multiple, :standing, to: :running, on_event: :walk, on: :move
assert_have_state multiple, :standing, on: :move
refute_have_state multiple, :walking, on: :move
assert_event_allowed multiple, :walk, on: :move
refute_event_allowed multiple, :hold, on: :move
assert_transition_to_allowed multiple, :walking, on: :move
refute_transition_to_allowed multiple, :running, on: :move
assert_transitions_from multiple, :sleeping, to: :processing, on_event: :start, on: :work
refute_transitions_from multiple, :sleeping, to: :sleeping, on_event: :start, on: :work
assert_have_state multiple, :sleeping, on: :work
refute_have_state multiple, :processing, on: :work
assert_event_allowed multiple, :start, on: :move
refute_event_allowed multiple, :stop, on: :move
assert_transition_to_allowed multiple, :processing, on: :move
refute_transition_to_allowed multiple, :sleeping, on: :move
```


Expectations

List of supported expectations: must_transition_from, wont_transition_from, must_have_state, wont_have_state, must_allow_event, wont_allow_event, must_allow_transition_to, wont_allow_transition_to.


Add require 'aasm/minitest_spec' to your test_helper.rb file and use them like this:


```ruby


classes with only the default state machine

job = Job.new
job.must_transition_from :sleeping, to: :running, on_event: :run
job.wont_transition_from :sleeping, to: :cleaning, on_event: :run
job.must_have_state :sleeping
job.wont_have_state :running
job.must_allow_event :run
job.wont_allow_event :clean
job.must_allow_transition_to :running
job.wont_allow_transition_to :cleaning


on_event also accept arguments

job.must_transition_from :sleeping, :defragmentation, to: :running, on_event: :run


classes with multiple state machine

multiple = SimpleMultipleExample.new
multiple.must_transition_from :standing, to: :walking, on_event: :walk, on: :move
multiple.wont_transition_from :standing, to: :running, on_event: :walk, on: :move
multiple.must_have_state :standing, on: :move
multiple.wont_have_state :walking, on: :move
multiple.must_allow_event :walk, on: :move
multiple.wont_allow_event :hold, on: :move
multiple.must_allow_transition_to :walking, on: :move
multiple.wont_allow_transition_to :running, on: :move
multiple.must_transition_from :sleeping, to: :processing, on_event: :start, on: :work
multiple.wont_transition_from :sleeping, to: :sleeping, on_event: :start, on: :work
multiple.must_have_state :sleeping, on: :work
multiple.wont_have_state :processing, on: :work
multiple.must_allow_event :start, on: :move
multiple.wont_allow_event :stop, on: :move
multiple.must_allow_transition_to :processing, on: :move
multiple.wont_allow_transition_to :sleeping, on: :move
```


Installation
Manually from RubyGems.org

sh
% gem install aasm


Or if you are using Bundler

```ruby


Gemfile

gem 'aasm'
```


Building your own gems

sh
% rake build
% sudo gem install pkg/aasm-x.y.z.gem


Generators

After installing AASM you can run generator:


sh
% rails generate aasm NAME [COLUMN_NAME]

Replace NAME with the Model name, COLUMN_NAME is optional(default is 'aasm_state').
This will create a model (if one does not exist) and configure it with aasm block.
For ActiveRecord orm a migration file is added to add aasm state column to table.


Docker

Run test suite easily on docker
1. docker-compose build aasm
2. docker-compose run --rm aasm


Latest changes

Take a look at the CHANGELOG for details about recent changes to the current version.


Questions?

Feel free to



Maintainers

Contributing
Warranty

This software is provided "as is" and without any express or
implied warranties, including, without limitation, the implied
warranties of merchantibility and fitness for a particular
purpose.


License

Copyright (c) 2006-2017 Scott Barron


Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:


The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.


THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.