Use update_column for newer Rails; ensure other dirty attributes are …

…not saved on state change

lib/workflow.rb

@@ -343,7 +343,13 @@ def load_workflow_state
     # On transition the new workflow state is immediately saved in the
     # database.
     def persist_workflow_state(new_value)
-      update_attribute self.class.workflow_column, new_value
+      if self.respond_to? :update_column
+        # Rails 3.1 or newer
+        update_column self.class.workflow_column, new_value
+      else
+        # older Rails; beware of side effect: other (pending) attribute changes will be persisted too
+        update_attribute self.class.workflow_column, new_value
+      end
     end
 
     private

test/new_versions/persistence_test.rb

@@ -0,0 +1,62 @@
+require 'test_helper'
+require 'active_record'
+require 'logger'
+require 'sqlite3'
+require 'workflow'
+require 'mocha/setup'
+require 'stringio'
+
+ActiveRecord::Migration.verbose = false
+
+class PersistenceTestOrder < ActiveRecord::Base
+  include Workflow
+
+  workflow do
+    state :submitted do
+      event :accept, :transitions_to => :accepted, :meta => {:doc_weight => 8} do |reviewer, args|
+      end
+    end
+    state :accepted do
+      event :ship, :transitions_to => :shipped
+    end
+    state :shipped
+  end
+
+  attr_accessible :title # protecting all the other attributes
+
+end
+
+PersistenceTestOrder.logger = Logger.new(STDOUT) # active_record 2.3 expects a logger instance
+PersistenceTestOrder.logger.level = Logger::WARN # switch to Logger::DEBUG to see the SQL statements
+
+class PersistenceTest < ActiveRecordTestCase
+
+  def setup
+    super
+
+    ActiveRecord::Schema.define do
+      create_table :persistence_test_orders do |t|
+        t.string :title, :null => false
+        t.string :workflow_state
+      end
+    end
+
+    exec "INSERT INTO persistence_test_orders(title, workflow_state) VALUES('order6', 'accepted')"
+  end
+
+  def assert_state(title, expected_state, klass = PersistenceTestOrder)
+    o = klass.find_by_title(title)
+    assert_equal expected_state, o.read_attribute(klass.workflow_column)
+    o
+  end
+
+  test 'ensure other dirty attributes are not saved on state change' do
+    o = assert_state 'order6', 'accepted'
+    o.title = 'going to change the title'
+    assert o.changed?
+    o.ship!
+    assert o.changed?, 'title should not be saved and the change still stay pending'
+  end
+
+end
+