Add two event callbacks:

aasm_event_fired(from, to) - called when an event is fired successfully
aasm_event_failed(event)   - called when an event fails

These could be used to implement transition logging [Artem Vasiliev] or
setting a timestamp column [Mike Ferrier] as well as other pieces of love and magic.

CHANGELOG

@@ -1,3 +1,6 @@
+* Add some event callbacks, #aasm_event_fired(from, to), and #aasm_event_failed(event)
+  Based on transition logging suggestion [Artem Vasiliev] and timestamp column suggestion [Mike Ferrier]
+
 * Add #aasm_events_for_state and #aasm_events_for_current_state [Joao Paulo Lins]
 
 * Ensure that a state is written for a new record even if aasm_current_state or

TODO

@@ -9,5 +9,3 @@ Cool ideas from users:
 
 * Support multiple state machines on one object (Chris Nelson)
 * http://justbarebones.blogspot.com/2007/11/actsasstatemachine-enhancements.html (Chetan Patil)
-* transition logging (Artem Vasiliev)
-* timestamp column for state change on AR (Mike Ferrier)

lib/aasm.rb

@@ -41,9 +41,17 @@ module AASM
       define_method("#{name.to_s}!") do
         new_state = self.class.aasm_events[name].fire(self)
         unless new_state.nil?
+          if self.respond_to?(:aasm_event_fired)
+            self.aasm_event_fired(self.aasm_current_state, new_state)
+          end
+          
           self.aasm_current_state = new_state
           true
         else
+          if self.respond_to?(:aasm_event_failed)
+            self.aasm_event_failed(name)
+          end
+          
           false
         end
       end

spec/unit/aasm_spec.rb

@@ -9,6 +9,14 @@ class Foo
   aasm_event :close do
     transitions :to => :closed, :from => [:open]
   end
+
+  aasm_event :null do
+    transitions :to => :closed, :from => [:open], :guard => :always_false
+  end
+
+  def always_false
+    false
+  end
 end
 
 class Bar
@@ -122,3 +130,27 @@ describe AASM, '- getting events for a state' do
     foo.aasm_events_for_current_state
   end
 end
+
+describe AASM, '- event callbacks' do
+  it 'should call aasm_event_fired if defined and successful' do
+    foo = Foo.new
+    def foo.aasm_event_fired(from, to)
+    end
+
+    foo.should_receive(:aasm_event_fired)
+
+    foo.close!
+  end
+
+  it 'should call aasm_event_failed if defined and transition failed' do
+    foo = Foo.new
+    def foo.aasm_event_failed(event)
+    end
+
+    foo.should_receive(:aasm_event_failed)
+
+    foo.null!
+  end
+end
+
+