json decode error

json_decode_error.rb

# THE SQL for the Case object is above the Case Object
# To generate error
# to run: bundle exec ruby json_decode_error.rb
# http://localhost:4567/start
#    Copy the WFID which is printed
# http://localhost:4567/history/:wfid

require 'rubygems'

require 'ruote'
require 'ruote/part/storage_participant'
require 'ruote/storage/fs_storage'
require 'yajl'
Rufus::Json.backend = :yajl
require 'pg'
require 'ruote-sequel'
require 'active_record'
require 'ruote-sequel'

connect_data = {
  :adapter   => 'postgresql',
  :database  => "bpm_reference_development",
  :username  => '', # your username
  :password  => '', # your password
  :host      => 'localhost',
  :port      => 5432
}

ActiveRecord::Base.configurations[:development] = connect_data
ActiveRecord::Base.include_root_in_json = true
ActiveRecord::Base.store_full_sti_class = true
ActiveSupport.use_standard_json_time_format = true
ActiveSupport.escape_html_entities_in_json = false
ActiveRecord::Base.establish_connection(ActiveRecord::Base.configurations[:development])

SEQUEL_CONNECTION =  Sequel.connect(connect_data.merge(:adapter => "postgres"))
Ruote::Sequel.create_table(SEQUEL_CONNECTION, false) unless SEQUEL_CONNECTION.tables.include?(:documents)
RUOTE_STORAGE = Ruote::Sequel::Storage.new(SEQUEL_CONNECTION, {}) # documented option - #   opts = { 'remote_definition_allowed' => true }

ENGINE = Ruote::Dashboard.new(Ruote::Worker.new(RUOTE_STORAGE))

ENGINE.register_participant :stage1 do |workitem|
  Case.update_case_stage(workitem.fields['reference'], "stage1")
  workitem.fields["case_result1"] = "Completed Stage 1"
end

ENGINE.register_participant :stage2 do |workitem|
  Case.update_case_stage(workitem.fields['reference'], "stage2")
  workitem.fields["case_result2"] = "Completed Stage 2"
end

ENGINE.register_participant :stage3 do |workitem|
  Case.update_case_stage(workitem.fields['reference'], "stage3")
  workitem.fields["case_result3"] = "Completed Stage 3"
end

STAGES_PDEF = Ruote.define do
  sequence do
    stage1
    stage2
    stage3
  end
end

module Ruote
  class StorageHistory
    def steps_by_process(wfid)
      # which ones were 'executed' - filters out items like setting up sequence and concurrence steps
      all_expressions = self.by_process(wfid)
      dispatched_expressions = all_expressions.select{|msg| 'dispatched' == msg["action"]}      
      # for all the msgessions, get the name and order by sorting by the original timestamp
      dispatched_expressions.map do |msg| 
        [msg['participant_name'], msg["original_put_at"]]
      end.sort{|a,b| a.last <=> b.last}.map{|exp| exp.first}
    end
  end
end

require 'ruote/log/storage_history'
ENGINE.add_service('history', Ruote::StorageHistory)


# CREATE TABLE cases (
#   id    SERIAL,
#   case_state  varchar(255)
# );
class Case < ActiveRecord::Base
  def self.update_case_stage(reference, state)
    kase = find(reference)
    kase.update_attributes(:case_state => state)
    kase
  end
end


#
# web resources (thanks to Sinatra)
#

require 'cgi'
require 'sinatra'
require 'haml'

get '/start' do
  kase = Case.create!
  ENGINE.launch(STAGES_PDEF, :reference => kase.id)
end

get '/history/:wfid' do
  ENGINE.history.steps_by_process(params[:wfid]).join(", ")
end