### Home Classes Methods

### In Files

- lib/state_machine/integrations/active_record/versions.rb
- lib/state_machine/integrations/active_record.rb

### Methods

- ::active?
- ::matching_ancestors
- #ancestors_for
- #around_save
- #attribute_column
- #create_scope
- #create_with_scope
- #create_without_scope
- #default_error_message_options
- #define_action_hook
- #define_dynamic_state_initializer
- #define_state_initializer
- #define_static_state_initializer
- #i18n_scope
- #invalidate
- #load_locale
- #load_observer_extensions
- #owner_class_ancestor_has_method?
- #owner_class_attribute_default
- #runs_validations_on_action?
- #supports_mass_assignment_security?
- #supports_observers?
- #supports_validations?
- #transaction
- #translate

### Included Modules

- StateMachine::Integrations::ActiveModel::Observer
- StateMachine::Integrations::Base
- StateMachine::Integrations::ActiveModel

### Files

- LICENSE

### Class/Module Index

Quicksearch

- StateMachine
- StateMachine::AllMatcher
- StateMachine::Assertions
- StateMachine::AttributeTransitionCollection
- StateMachine::BlacklistMatcher
- StateMachine::Branch
- StateMachine::Callback
- StateMachine::ClassMethods
- StateMachine::Error
- StateMachine::EvalHelpers
- StateMachine::Event
- StateMachine::EventCollection
- StateMachine::Graph
- StateMachine::InstanceMethods
- StateMachine::IntegrationNotFound
- StateMachine::Integrations
- StateMachine::Integrations::ActiveModel
- StateMachine::Integrations::ActiveModel::Observer
- StateMachine::Integrations::ActiveModel::ObserverUpdate
- StateMachine::Integrations::ActiveRecord
- StateMachine::Integrations::Base
- StateMachine::Integrations::Base::ClassMethods
- StateMachine::Integrations::DataMapper
- StateMachine::Integrations::DataMapper::Observer
- StateMachine::Integrations::MongoMapper
- StateMachine::Integrations::Mongoid
- StateMachine::Integrations::Sequel
- StateMachine::InvalidEvent
- StateMachine::InvalidParallelTransition
- StateMachine::InvalidTransition
- StateMachine::LoopbackMatcher
- StateMachine::Machine
- StateMachine::MachineCollection
- StateMachine::MacroMethods
- StateMachine::Matcher
- StateMachine::MatcherHelpers
- StateMachine::NodeCollection
- StateMachine::Path
- StateMachine::PathCollection
- StateMachine::RailsEngine
- StateMachine::State
- StateMachine::StateCollection
- StateMachine::StateContext
- StateMachine::Transition
- StateMachine::TransitionCollection
- StateMachine::WhitelistMatcher
- StateMachine::YARD
- StateMachine::YARD::Handlers
- StateMachine::YARD::Handlers::Base
- StateMachine::YARD::Handlers::Event
- StateMachine::YARD::Handlers::Machine
- StateMachine::YARD::Handlers::State
- StateMachine::YARD::Handlers::Transition
- Object

No matching classes.

# StateMachine::Integrations::ActiveRecord

Adds support for integrating state machines with ActiveRecord models.

## Examples

Below is an example of a simple state machine defined within an ActiveRecord model:

    class Vehicle < ActiveRecord::Base
      state_machine :initial => :parked do
        event :ignite do
          transition :parked => :idling
        end
      end
    end

The examples in the sections below will use the above class as a reference.

## Actions

By default, the action that will be invoked when a state is transitioned is the `save` action. This will cause the record to save the changes made to the state machine's attribute. Note that if any other changes were made to the record prior to transition, then those changes will be saved as well.

For example,

    vehicle = Vehicle.create          # => #<Vehicle id: 1, name: nil, state: "parked">
    vehicle.name = 'Ford Explorer'
    vehicle.ignite                    # => true
    vehicle.reload                    # => #<Vehicle id: 1, name: "Ford Explorer", state: "idling">

## Events

As described in StateMachine::InstanceMethods#state_machine, event attributes are created for every machine that allow transitions to be performed automatically when the object's action (in this case, :save) is called.

In ActiveRecord, these automated events are run in the following order:

- before validation - Run before callbacks and persist new states, then validate

- before save - If validation was skipped, run before callbacks and persist new states, then save

- after save - Run after callbacks

For example,

    vehicle = Vehicle.create          # => #<Vehicle id: 1, name: nil, state: "parked">
    vehicle.state_event               # => nil
    vehicle.state_event = 'invalid'
    vehicle.valid?                    # => false
    vehicle.errors.full_messages      # => ["State event is invalid"]

    vehicle.state_event = 'ignite'
    vehicle.valid?                    # => true
    vehicle.save                      # => true
    vehicle.state                     # => "idling"
    vehicle.state_event               # => nil

Note that this can also be done on a mass-assignment basis:

    vehicle = Vehicle.create(:state_event => 'ignite')  # => #<Vehicle id: 1, name: nil, state: "idling">
    vehicle.state                                       # => "idling"

This technique is always used for transitioning states when the `save` action (which is the default) is configured for the machine.

### Security implications

Beware that public event attributes mean that events can be fired whenever mass-assignment is being used. If you want to prevent malicious users from tampering with events through URLs / forms, the attribute should be protected like so:

    class Vehicle < ActiveRecord::Base
      attr_protected :state_event
      # attr_accessible ... # Alternative technique

      state_machine do
        ...
      end
    end

If you want to only have some events be able to fire via mass-assignment, you can build two state machines (one public and one protected) like so:

    class Vehicle < ActiveRecord::Base
      attr_protected :state_event # Prevent access to events in the first machine

      state_machine do
        # Define private events here
      end

      # Public machine targets the same state as the private machine
      state_machine :public_state, :attribute => :state do
        # Define public events here
      end
    end

## Transactions

In order to ensure that any changes made during transition callbacks are rolled back during a failed attempt, every transition is wrapped within a transaction.

For example,

    class Message < ActiveRecord::Base
    end

    Vehicle.state_machine do
      before_transition do |vehicle, transition|
        Message.create(:content => transition.inspect)
        false
      end
    end

    vehicle = Vehicle.create      # => #<Vehicle id: 1, name: nil, state: "parked">
    vehicle.ignite                # => false
    Message.count                 # => 0

Note that only before callbacks that halt the callback chain and failed attempts to save the record will result in the transaction being rolled back. If an after callback halts the chain, the previous result still applies and the transaction is not rolled back.

To turn off transactions:

    class Vehicle < ActiveRecord::Base
      state_machine :initial => :parked, :use_transactions => false do
        ...
      end
    end

## Validations

As mentioned in StateMachine::Machine#state, you can define behaviors, like validations, that only execute for certain states. One important caveat here is that, due to a constraint in ActiveRecord's validation framework, custom validators will not work as expected when defined to run in multiple states. For example:

    class Vehicle < ActiveRecord::Base
      state_machine do
        ...
        state :first_gear, :second_gear do
          validate :speed_is_legal
        end
      end
    end

In this case, the `:speed_is_legal` validation will only get run for the `:second_gear` state. To avoid this, you can define your custom validation like so:

    class Vehicle < ActiveRecord::Base
      state_machine do
        ...
        state :first_gear, :second_gear do
          validate {|vehicle| vehicle.speed_is_legal}
        end
      end
    end

## Validation errors

If an event fails to successfully fire because there are no matching transitions for the current record, a validation error is added to the record's state attribute to help in determining why it failed and for reporting via the UI.

For example,

    vehicle = Vehicle.create(:state => 'idling')  # => #<Vehicle id: 1, name: nil, state: "idling">
    vehicle.ignite                                # => false
    vehicle.errors.full_messages                  # => ["State cannot transition via \"ignite\""]

If an event fails to fire because of a validation error on the record and not because a matching transition was not available, no error messages will be added to the state attribute.

In addition, if you're using the `ignite!` version of the event, then the failure reason (such as the current validation errors) will be included in the exception that gets raised when the event fails. For example, assuming there's a validation on a field called `name` on the class:

    vehicle = Vehicle.new
    vehicle.ignite!       # => StateMachine::InvalidTransition: Cannot transition state via :ignite from :parked (Reason(s): Name cannot be blank)

## Scopes

To assist in filtering models with specific states, a series of named scopes are defined on the model for finding records with or without a particular set of states.

These named scopes are essentially the functional equivalent of the following definitions:

    class Vehicle < ActiveRecord::Base
      named_scope :with_states, lambda {|*states| {:conditions => {:state => states}}}
      # with_states also aliased to with_state

      named_scope :without_states, lambda {|*states| {:conditions => ['state NOT IN (?)', states]}}
      # without_states also aliased to without_state
    end

Note, however, that the states are converted to their stored values before being passed into the query.

Because of the way named scopes work in ActiveRecord, they can be chained like so:

    Vehicle.with_state(:parked).all(:order => 'id DESC')

Note that states can also be referenced by the string version of their name:

    Vehicle.with_state('parked')

## Callbacks

All before/after transition callbacks defined for ActiveRecord models behave in the same way that other ActiveRecord callbacks behave. The object involved in the transition is passed in as an argument.

For example,

    class Vehicle < ActiveRecord::Base
      state_machine :initial => :parked do
        before_transition any => :idling do |vehicle|
          vehicle.put_on_seatbelt
        end

        before_transition do |vehicle, transition|
          # log message
        end

        event :ignite do
          transition :parked => :idling
        end
      end

      def put_on_seatbelt
        ...
      end
    end

Note, also, that the transition can be accessed by simply defining additional arguments in the callback block.

### Failure callbacks

`after_failure` callbacks allow you to execute behaviors when a transition is allowed, but fails to save. This could be useful for something like auditing transition attempts. Since callbacks run within transactions in ActiveRecord, a save failure will cause any records that get created in your callback to roll back. You can work around this issue like so:

    class TransitionLog < ActiveRecord::Base
      establish_connection Rails.env.to_sym
    end

    class Vehicle < ActiveRecord::Base
      state_machine do
        after_failure do |vehicle, transition|
          TransitionLog.create(:vehicle => vehicle, :transition => transition)
        end

        ...
      end
    end

The `TransitionLog` model establishes a second connection to the database that allows new records to be saved without being affected by rollbacks in the `Vehicle` model's transaction.

### Callback Order

Callbacks occur in the following order. Callbacks specific to state_machine are bolded. The remaining callbacks are part of ActiveRecord.

- (-) save

- (-) begin transaction (if enabled)

- (1) before_transition

- (-) valid

- (2) before_validation

- (-) validate

- (3) after_validation

- (4) before_save

- (5) before_create

- (-) create

- (6) after_create

- (7) after_save

- (8) after_transition

- (-) end transaction (if enabled)

- (9) after_commit

## Observers

In addition to support for ActiveRecord-like hooks, there is additional support for ActiveRecord observers. Because of the way ActiveRecord observers are designed, there is less flexibility around the specific transitions that can be hooked in. However, a large number of hooks are supported. For example, if a transition for a record's `state` attribute changes the state from `parked` to `idling` via the `ignite` event, the following observer methods are supported:

- before/after/after_failure_to-_ignite_from_parked_to_idling

- before/after/after_failure_to-_ignite_from_parked

- before/after/after_failure_to-_ignite_to_idling

- before/after/after_failure_to-_ignite

- before/after/after_failure_to-_transition_state_from_parked_to_idling

- before/after/after_failure_to-_transition_state_from_parked

- before/after/after_failure_to-_transition_state_to_idling

- before/after/after_failure_to-_transition_state

- before/after/after_failure_to-_transition

The following class shows an example of some of these hooks:

    class VehicleObserver < ActiveRecord::Observer
      def before_save(vehicle)
        # log message
      end

      # Callback for :ignite event *before* the transition is performed
      def before_ignite(vehicle, transition)
        # log message
      end

      # Callback for :ignite event *after* the transition has been performed
      def after_ignite(vehicle, transition)
        # put on seatbelt
      end

      # Generic transition callback *before* the transition is performed
      def after_transition(vehicle, transition)
        Audit.log(vehicle, transition)
      end
    end

More flexible transition callbacks can be defined directly within the model as described in StateMachine::Machine#before_transition and StateMachine::Machine#after_transition.

To define a single observer for multiple state machines:

    class StateMachineObserver < ActiveRecord::Observer
      observe Vehicle, Switch, Project

      def after_transition(record, transition)
        Audit.log(record, transition)
      end
    end

## Internationalization

In Rails 2.2+, any error message that is generated from performing invalid transitions can be localized. The following default translations are used:

    en:
      activerecord:
        errors:
          messages:
            invalid: "is invalid"
            # %{value} = attribute value, %{state} = Human state name
            invalid_event: "cannot transition when %{state}"
            # %{value} = attribute value, %{event} = Human event name, %{state} = Human current state name
            invalid_transition: "cannot transition via %{event}"

Notice that the interpolation syntax is %{key} in Rails 3+. In Rails 2.x, the appropriate syntax is {{key}}.

You can override these for a specific model like so:

    en:
      activerecord:
        errors:
          models:
            user:
              invalid: "is not valid"

In addition to the above, you can also provide translations for the various states / events in each state machine. Using the Vehicle example, state translations will be looked for using the following keys, where `model_name` = "vehicle", `machine_name` = "state" and `state_name` = "parked":

- `activerecord.state_machines.#{model_name}.#{machine_name}.states.#{state_name}`

- `activerecord.state_machines.#{model_name}.states.#{state_name}`

- `activerecord.state_machines.#{machine_name}.states.#{state_name}`

- `activerecord.state_machines.states.#{state_name}`

Event translations will be looked for using the following keys, where `model_name` = "vehicle", `machine_name` = "state" and `event_name` = "ignite":

- `activerecord.state_machines.#{model_name}.#{machine_name}.events.#{event_name}`

- `activerecord.state_machines.#{model_name}.events.#{event_name}`

- `activerecord.state_machines.#{machine_name}.events.#{event_name}`

- `activerecord.state_machines.events.#{event_name}`

An example translation configuration might look like so:

    es:
      activerecord:
        state_machines:
          states:
            parked: 'estacionado'
          events:
            park: 'estacionarse'

### Public Class Methods

active?() click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 5
    def self.active?
      ::ActiveRecord::VERSION::MAJOR == 2 || ::ActiveRecord::VERSION::MAJOR == 3 && ::ActiveRecord::VERSION::MINOR == 0
    end

matching_ancestors() click to toggle source

Classes that inherit from ActiveRecord::Base will automatically use the ActiveRecord integration.

    # File lib/state_machine/integrations/active_record.rb, line 421
    def self.matching_ancestors
      %(ActiveRecord::Base)
    end

### Public Instance Methods

ancestors_for(klass) click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 107
    def ancestors_for(klass)
      klass.self_and_descendents_from_active_record
    end

create_scope(name, scope) click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 29
    def create_scope(name, scope)
      if owner_class.respond_to?(:named_scope)
        name = name.to_sym
        machine_name = self.name

        # Since ActiveRecord does not allow direct access to the model
        # being used within the evaluation of a dynamic named scope, the
        # scope must be generated manually.  It's necessary to have access
        # to the model so that the state names can be translated to their
        # associated values and so that inheritance is respected properly.
        owner_class.named_scope(name)
        owner_class.scopes[name] = lambda do |model, *states|
          machine_states = model.state_machine(machine_name).states
          values = states.flatten.map {|state| machine_states.fetch(state).value}

          ::ActiveRecord::NamedScope::Scope.new(model, :conditions => scope.call(values))
        end
      end

      # Prevent the Machine class from wrapping the scope
      false
    end

default_error_message_options(object, attribute, message) click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 97
    def default_error_message_options(object, attribute, message)
      {:default => @messages[message]}
    end

define_static_state_initializer() click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 9
    def define_static_state_initializer
      define_helper :instance,             def attributes_from_column_definition(*)              result = super              self.class.state_machines.initialize_states(self, :static => :force, :dynamic => false, :to => result)              result            end, __FILE__, __LINE__ + 1
    end

i18n_scope(klass) click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 80
    def i18n_scope(klass)
      :activerecord
    end

invalidate(object, attribute, message, values = []) click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 52
    def invalidate(object, attribute, message, values = [])
      if defined?(I18n)
        super
      else
        object.errors.add(self.attribute(attribute), generate_message(message, values))
      end
    end

load_locale() click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 25
    def load_locale
      super if defined?(I18n)
    end

load_observer_extensions() click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 84
    def load_observer_extensions
      super
      ::ActiveRecord::Observer.class_eval do
        include StateMachine::Integrations::ActiveModel::Observer
      end unless ::ActiveRecord::Observer < StateMachine::Integrations::ActiveModel::Observer
    end

supports_mass_assignment_security?() click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 76
    def supports_mass_assignment_security?
      true
    end

supports_observers?() click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 68
    def supports_observers?
      true
    end

supports_validations?() click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 72
    def supports_validations?
      true
    end

translate(klass, key, value) click to toggle source

    # File lib/state_machine/integrations/active_record/versions.rb, line 60
    def translate(klass, key, value)
      if defined?(I18n)
        super
      else
        value ? value.to_s.humanize.downcase : 'nil'
      end
    end

### Protected Instance Methods

around_save(object) click to toggle source

Runs state events around the machine's :save action

    # File lib/state_machine/integrations/active_record.rb, line 500
    def around_save(object)
      transaction(object) do
        object.class.state_machines.transitions(object, action).perform { yield }
      end
    end

attribute_column() click to toggle source

Generates the fully-qualifed column name for this machine's attribute

    # File lib/state_machine/integrations/active_record.rb, line 519
    def attribute_column
      connection = owner_class.connection
      "#{connection.quote_table_name(owner_class.table_name)}.#{connection.quote_column_name(attribute)}"
    end

create_with_scope(name) click to toggle source

Creates a scope for finding records with a particular state or states for the attribute

    # File lib/state_machine/integrations/active_record.rb, line 508
    def create_with_scope(name)
      create_scope(name, lambda {|values| ["#{attribute_column} IN (?)", values]})
    end

create_without_scope(name) click to toggle source

Creates a scope for finding records without a particular state or states for the attribute

    # File lib/state_machine/integrations/active_record.rb, line 514
    def create_without_scope(name)
      create_scope(name, lambda {|values| ["#{attribute_column} NOT IN (?)", values]})
    end

define_action_hook() click to toggle source

Uses around callbacks to run state events if using the :save hook

    # File lib/state_machine/integrations/active_record.rb, line 479
    def define_action_hook
      if action_hook == :save
        define_helper :instance,               def save(*)                self.class.state_machine(#{name.inspect}).send(:around_save, self) { super }              end                            def save!(*)                self.class.state_machine(#{name.inspect}).send(:around_save, self) { super } || raise(ActiveRecord::RecordInvalid.new(self))              end                            def changed_for_autosave?                super || self.class.state_machines.any? {|name, machine| machine.action == :save && machine.read(self, :event)}              end, __FILE__, __LINE__ + 1
      else
        super
      end
    end

define_dynamic_state_initializer() click to toggle source

Initializes dynamic states

    # File lib/state_machine/integrations/active_record.rb, line 467
    def define_dynamic_state_initializer
      define_helper :instance,             def initialize(*)              super do |*args|                self.class.state_machines.initialize_states(self, :static => false)                yield(*args) if block_given?              end            end, __FILE__, __LINE__ + 1
    end

define_state_initializer() click to toggle source

Defines an initialization hook into the owner class for setting the initial state of the machine before any attributes are set on the object

    # File lib/state_machine/integrations/active_record.rb, line 446
    def define_state_initializer
      define_static_state_initializer
      define_dynamic_state_initializer
    end

owner_class_ancestor_has_method?(scope, method) click to toggle source

ActiveModel's use of method_missing / respond_to for attribute methods breaks both ancestor lookups and defined?(super). Need to special-case the existence of query attribute methods.

    # File lib/state_machine/integrations/active_record.rb, line 543
    def owner_class_ancestor_has_method?(scope, method)
      scope == :instance && method == "#{attribute}?" ? owner_class : super
    end

owner_class_attribute_default() click to toggle source

Gets the db default for the machine's attribute

    # File lib/state_machine/integrations/active_record.rb, line 437
    def owner_class_attribute_default
      if owner_class.connected? && owner_class.table_exists? && column = owner_class.columns_hash[attribute.to_s]
        column.default
      end
    end

runs_validations_on_action?() click to toggle source

Only runs validations on the action if using `:save`

    # File lib/state_machine/integrations/active_record.rb, line 432
    def runs_validations_on_action?
      action == :save
    end

transaction(object) click to toggle source

Runs a new database transaction, rolling back any changes by raising an ActiveRecord::Rollback exception if the yielded block fails (i.e. returns false).

    # File lib/state_machine/integrations/active_record.rb, line 527
    def transaction(object)
      result = nil
      object.class.transaction do
        raise ::ActiveRecord::Rollback unless result = yield
      end
      result
    end

[Validate]

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