Sequencer

sequencing.rb

# migration
t.integer  :sequence

# controller action
# and the way we've done the method, it's probably logical to put the action in test_scenarios_controller
def sequence
  TestScenario.sequence=(params[:sequence])
  render :json => { :status => :ok }
end

# routes.rb
put  'sequence',        :on => :collection

# sequencer module
module Concerns::Sequence
  extend ActiveSupport::Concern

  included do
    default_scope :order => :sequence
    before_create :set_sequence
  end

  def set_sequence
    self.sequence = (self.class.maximum('sequence') || 0) + 1 unless self.sequence
  end

  module ClassMethods
    def sequence=(params)
      transaction do
        params.each_pair do |key, value|
          if record = find(value["id"])
            record.update_attributes!(:sequence => key)
          end
        end
      end
    end
  end
end

# test scenario
include Concerns::Sequence

# in the view
%table.sortable(data-url='#{path_to_the_sequence_action}')
  #...
  # this will add the id for each table row
  %tr[test_scenario]
  
# And then you can use jquery ui sortable to move the rows around
# and have a event callback to send the order of rows and ids back to the path you specified in the data-url
# Let me know if you need help with that part

# a test from a previous project
it 'should order questions according to sequence' do
  @module = ...
  [4, 2, 1, 5, 3].each do |sequence|
    q = create(:training_question, :training_module_id => @module.id, :text => sequence.to_s, :sequence => sequence)
  end
  # and then check that the sequence is kept
  @module.reload
  assert_equal '1', @module.questions.first.text
end

# this is just an example for one of the test