Adds ability to select different adapters via a workflow_adapter class method.

README.markdown

@@ -363,6 +363,26 @@ also know, if you need any interface beyond `load_workflow_state` and
 `persist_workflow_state` methods to implement an adapter for your
 favorite database.
 
+
+Custom Versions of Existing Adapters
+------------------------------------
+
+Other adapters (such as a custom ActiveRecord plugin) can be selected by adding a `workflow_adapter` class method, eg.
+
+```ruby
+class Example < ActiveRecord::Base
+  def self.workflow_adapter
+    MyCustomAdapter
+  end
+  include Workflow
+
+  # ...
+end
+```
+
+(The above will include `MyCustomAdapter` *instead* of `Workflow::Adapter::ActiveRecord`.)
+
+
 Accessing your workflow specification
 -------------------------------------
 

lib/workflow.rb

@@ -262,15 +262,15 @@ def self.included(klass)
 
     klass.extend ClassMethods
 
-    if Object.const_defined?(:ActiveRecord)
-      if klass < ActiveRecord::Base
-        klass.send :include, Adapter::ActiveRecord::InstanceMethods
-        klass.send :extend, Adapter::ActiveRecord::Scopes
-        klass.before_validation :write_initial_state
+    # Look for a hook; otherwise detect based on ancestor class.
+    if klass.respond_to?(:workflow_adapter)
+      klass.send :include, klass.workflow_adapter
+    else
+      if Object.const_defined?(:ActiveRecord) && klass < ActiveRecord::Base
+        klass.send :include, Adapter::ActiveRecord
       end
-    elsif Object.const_defined?(:Remodel)
-      if klass < Adapter::Remodel::Entity
-        klass.send :include, Remodel::InstanceMethods
+      if Object.const_defined?(:Remodel) && klass < Adapter::Remodel::Entity
+        klass.send :include, Adapter::Remodel::InstanceMethods
       end
     end
   end

lib/workflow/adapters/active_record.rb

@@ -1,6 +1,12 @@
 module Workflow
   module Adapter
     module ActiveRecord
+      def self.included(klass)
+        klass.send :include, Adapter::ActiveRecord::InstanceMethods
+        klass.send :extend, Adapter::ActiveRecord::Scopes
+        klass.before_validation :write_initial_state
+      end
+
       module InstanceMethods
         def load_workflow_state
           read_attribute(self.class.workflow_column)

test/adapter_hook_test.rb

@@ -0,0 +1,52 @@
+require File.join(File.dirname(__FILE__), 'test_helper')
+require 'workflow'
+class AdapterHookTest < ActiveRecordTestCase
+  test 'hook to choose adapter' do
+
+    ActiveRecord::Schema.define do
+      create_table(:examples) { |t| t.string :workflow_state }
+    end
+
+    class DefaultAdapter < ActiveRecord::Base
+      self.table_name = :examples
+      include Workflow
+      workflow do
+        state(:initial) { event :progress, :transitions_to => :last }
+        state(:last)
+      end
+    end
+
+    class ChosenByHookAdapter < ActiveRecord::Base
+      self.table_name = :examples
+      attr_reader :foo
+      def self.workflow_adapter
+        Module.new do
+          def load_workflow_state
+            @foo if defined?(@foo)
+          end
+          def persist_workflow_state(new_value)
+            @foo = new_value
+          end
+        end
+      end
+
+      include Workflow
+      workflow do
+        state(:initial) { event :progress, :transitions_to => :last }
+        state(:last)
+      end
+    end
+
+    default = DefaultAdapter.create
+    assert default.initial?
+    default.progress!
+    assert default.last?
+    assert DefaultAdapter.find(default.id).last?, 'should have persisted via ActiveRecord'
+
+    hook = ChosenByHookAdapter.create
+    assert hook.initial?
+    hook.progress!
+    assert_equal hook.foo, 'last', 'should have "persisted" with custom adapter'
+    assert ChosenByHookAdapter.find(hook.id).initial?, 'should not have persisted via ActiveRecord'
+  end
+end