supporting ActiveRecord transactions when firing an event

CHANGELOG.md

@@ -1,5 +1,9 @@
 # CHANGELOG
 
+## 3.0.13
+
+ * supporting ActiveRecord transactions when firing an event
+
 ## 3.0.12
 
  * aasm_from_states_for_state now supports to filter for specific transition

README.md

@@ -5,7 +5,13 @@ This package contains AASM, a library for adding finite state machines to Ruby c
 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
 [ActiveRecord](http://api.rubyonrails.org/classes/ActiveRecord/Base.html) and
-[Mongoid](http://mongoid.org/).
+[Mongoid](http://mongoid.org/), but it can be used for any Ruby class, no matter its
+parent class.
+
+### Transaction support
+
+Since version 3.0.13 AASM supports ActiveRecord transactions. So whenever a transition
+callback fails, all changes to any database record are rolled back.
 
 ## Features ##
 

lib/aasm/aasm.rb

@@ -7,7 +7,7 @@ module AASM
       AASM::StateMachine[base] = AASM::StateMachine.new('')
     end
     AASM::Persistence.set_persistence(base)
-   super
+    super
   end
 
   module ClassMethods
@@ -72,7 +72,7 @@ module AASM
     def aasm_human_event_name(event)
       AASM::SupportingClasses::Localizer.new.human_event_name(self, event)
     end
-  end
+  end # ClassMethods
 
   # this method does what? does it deliver the current state?
   def aasm_current_state

lib/aasm/persistence/active_record_persistence.rb

@@ -149,6 +149,12 @@ module AASM
           aasm_enter_initial_state if send(self.class.aasm_column).blank?
         end
 
+        def aasm_fire_event(name, options, *args)
+          transaction do
+            super
+          end
+        end
+
       end
 
       module WriteStateWithoutPersistence

spec/models/transactor.rb

@@ -0,0 +1,26 @@
+require 'active_record'
+class Transactor < ActiveRecord::Base
+
+  belongs_to :worker
+
+  include AASM
+  aasm :column => :status do
+    state :sleeping, :initial => true
+    state :running, :before_enter => :start_worker, :after_enter => :fail
+
+    event :run do
+      transitions :to => :running, :from => :sleeping
+    end
+  end
+
+private
+
+  def start_worker
+    worker.update_attribute(:status, 'running')
+  end
+
+  def fail
+    raise StandardError.new('failed on purpose')
+  end
+
+end

spec/models/worker.rb

@@ -0,0 +1,2 @@
+class Worker < ActiveRecord::Base
+end

spec/schema.rb

@@ -11,6 +11,17 @@ ActiveRecord::Schema.define(:version => 0) do
     t.string "status"
   end
 
+  create_table "transactors", :force => true do |t|
+    t.string "name"
+    t.string "status"
+    t.integer "worker_id"
+  end
+
+  create_table "workers", :force => true do |t|
+    t.string "name"
+    t.string "status"
+  end
+
   create_table "invalid_persistors", :force => true do |t|
     t.string "name"
     t.string "status"

spec/unit/active_record_persistence_spec.rb

@@ -1,6 +1,7 @@
 require 'rubygems'
 require 'active_record'
 require 'logger'
+require 'spec_helper'
 
 load_schema
 
@@ -317,4 +318,17 @@ describe 'transitions with persistence' do
     persistor.should_not be_sleeping
   end
 
+  describe 'transactions' do
+    it 'should rollback all changes' do
+      worker = Worker.create!(:name => 'worker', :status => 'sleeping')
+      transactor = Transactor.create!(:name => 'transactor', :worker => worker)
+      transactor.should be_sleeping
+      worker.status.should == 'sleeping'
+
+      lambda {transactor.run!}.should raise_error(StandardError, 'failed on purpose')
+      transactor.should be_running
+      worker.reload.status.should == 'sleeping'
+    end
+  end
+
 end