mongo_readonly_patch.rb

# encoding: utf-8

=begin
Mongoid::Errors::ReadonlyDocument:
message:
  Attempted to persist the readonly document 'Offer'.
summary:
  Documents loaded from the database using #only cannot be persisted.
resolution:
  Don't attempt to persist documents that are flagged as readonly.
=end

# https://github.com/mongodb/mongoid/blob/5.0.0-stable/lib/mongoid/stateful.rb#L72

require "mongoid/document"

unless Class.new.tap { |klass| klass.send(:include, Mongoid::Document) }.instance_methods.include?(:readonly?)
  abort "#{__FILE__}: Mongoid::Document does not include #readonly? method that is going to be patched"
end

module Mongoid
  module Document
    def readonly?
      #__selected_fields != nil
      #->
      false
    end
  end
end