### Home Classes Methods

### In Files

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

### Methods

- ::active?
- ::matching_ancestors
- #around_save
- #attribute_field
- #create_with_scope
- #create_without_scope
- #define_action_hook
- #define_scope
- #define_state_accessor
- #define_state_initializer
- #owner_class_attribute_default
- #runs_validations_on_action?

### Included Modules

- 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
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- 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
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- 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
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- 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::Mongoid

Adds support for integrating state machines with Mongoid models.

## Examples

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

    class Vehicle
      include Mongoid::Document

      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: 4d70e028b876bb54d9000003, name: nil, state: "parked">
    vehicle.name = 'Ford Explorer'
    vehicle.ignite                    # => true
    vehicle.reload                    # => #<Vehicle _id: 4d70e028b876bb54d9000003, 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 Mongoid, 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: 4d70e028b876bb54d9000003, 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: 4d70e028b876bb54d9000003, 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
      include Mongoid::Document

      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
      include Mongoid::Document

      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

## 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 Mongoid's validation framework, custom validators will not work as expected when defined to run in multiple states. For example:

    class Vehicle
      include Mongoid::Document

      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
      include Mongoid::Document

      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: 4d70e028b876bb54d9000003, 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 basic scopes are defined on the model for finding records with or without a particular set of states.

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

    class Vehicle
      include Mongoid::Document

      scope :with_states, lambda {|*states| where(:state => {'$in' => states})}
      # with_states also aliased to with_state

      scope :without_states, lambda {|*states| where(:state => {'$nin' => 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 Mongoid, they cannot be chained.

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 Mongoid models behave in the same way that other Mongoid callbacks behave. The object involved in the transition is passed in as an argument.

For example,

    class Vehicle
      include Mongoid::Document

      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.

## Observers

In addition to support for Mongoid-like hooks, there is additional support for Mongoid observers. Because of the way Mongoid 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 < Mongoid::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 < Mongoid::Observer
      observe Vehicle, Switch, Project

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

### Callback Order

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

- (-) save

- (1) before_transition

- (-) valid

- (2) before_validation

- (3) after_validation

- (4) before_save

- (5) before_create

- (6) after_create

- (7) after_save

- (8) after_transition

## Internationalization

Any error message that is generated from performing invalid transitions can be localized. The following default translations are used:

    en:
      mongoid:
        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}"

You can override these for a specific model like so:

    en:
      mongoid:
        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":

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

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

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

- `mongoid.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":

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

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

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

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

An example translation configuration might look like so:

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

### Public Class Methods

active?() click to toggle source

    # File lib/state_machine/integrations/mongoid/versions.rb, line 5
    def self.active?
      ::Mongoid::VERSION =~ /^2\./
    end

matching_ancestors() click to toggle source

Classes that include Mongoid::Document will automatically use the Mongoid integration.

    # File lib/state_machine/integrations/mongoid.rb, line 362
    def self.matching_ancestors
      %(Mongoid::Document)
    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/mongoid.rb, line 439
    def around_save(object)
      object.class.state_machines.transitions(object, action).perform { yield }
    end

attribute_field() click to toggle source

Gets the field for this machine's attribute (if it exists)

    # File lib/state_machine/integrations/mongoid.rb, line 383
    def attribute_field
      owner_class.fields[attribute.to_s] || owner_class.fields[owner_class.aliased_fields[attribute.to_s]]
    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/mongoid.rb, line 445
    def create_with_scope(name)
      define_scope(name, lambda {|values| {attribute => {'$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/mongoid.rb, line 451
    def create_without_scope(name)
      define_scope(name, lambda {|values| {attribute => {'$nin' => 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/mongoid.rb, line 417
    def define_action_hook
      if action_hook == :save
        define_helper :instance,               def insert(*)                self.class.state_machine(#{name.inspect}).send(:around_save, self) { super.persisted? }                self              end                            def update(*)                self.class.state_machine(#{name.inspect}).send(:around_save, self) { super }              end                            def upsert(*)                self.class.state_machine(#{name.inspect}).send(:around_save, self) { super }              end, __FILE__, __LINE__ + 1
      else
        super
      end
    end

define_scope(name, scope) click to toggle source

Defines a new scope with the given name

    # File lib/state_machine/integrations/mongoid.rb, line 456
    def define_scope(name, scope)
      lambda {|model, values| model.criteria.where(scope.call(values))}
    end

define_state_accessor() click to toggle source

Skips defining reader/writer methods since this is done automatically

    # File lib/state_machine/integrations/mongoid.rb, line 411
    def define_state_accessor
      owner_class.field(attribute, :type => String) unless attribute_field
      super
    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/mongoid.rb, line 390
    def define_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                        def apply_pre_processed_defaults              defaults = {}              self.class.state_machines.initialize_states(self, :static => :force, :dynamic => false, :to => defaults)              defaults.each do |attr, value|                send(:"\#{attr}=", value) unless attributes.include?(attr)              end              super            end, __FILE__, __LINE__ + 1
    end

owner_class_attribute_default() click to toggle source

Gets the db default for the machine's attribute

    # File lib/state_machine/integrations/mongoid.rb, line 378
    def owner_class_attribute_default
      attribute_field && attribute_field.default_val
    end

runs_validations_on_action?() click to toggle source

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

    # File lib/state_machine/integrations/mongoid.rb, line 373
    def runs_validations_on_action?
      action == :save
    end

[Validate]

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