A service object that takes a trackable object, action, and parameters, and creates an Activity record for action auditing.

activity_creator.rb

class ActivityCreator

  def initialize(action, trackable, contact, comment=nil)
    @trackable = trackable                     # the affected object (could be the same as contact)
    @action    = action                        # what was done
    @comment   = comment
    @changes   = collect_changes
  end

  def call
    attrs = {
      tenant_id:       Tenant.current_id,
      user_id:         User.current_id,
      trackable:       trackable,
      action:          action,
      tracked_changes: changes
    }
    unless changes.empty? && action == 'update'
      Activity.create!(attrs)
    end
  end

  attr_accessor :user, :action, :trackable, :contact, :comment, :changes
  private

  IGNORE_ATTRS = [
    :created_at,
    :password_digest,
    :registration_token,
    :auth_token,
    :tenant_id,
    :updated_at,
  ]

  def remove_empty(changes)
    changes.delete_if{|k,v| v[0].blank? and v[1].blank?}
  end

  def collect_changes
    if action == 'create'
      IGNORE_ATTRS.push(:id)
    end
    changes = trackable.previous_changes.except(*IGNORE_ATTRS)
    changes = remove_empty(changes)
    changes = changes
  end

end