#{rel}_ids= with Mongoid HABTM

output

% ./test.rb
a.b_ids = [b.id]
a.b_ids: ["509ba6a40b32cb7486000001"]
a.bs: []
b.a_ids: []
b.as: []

a.bs = [b]
a.b_ids: ["509ba6a40b32cb7486000001"]
a.bs: [#<B _id: 509ba6a40b32cb7486000001, _type: nil, a_ids: ["509ba6a40b32cb7486000002"]>]
b.a_ids: ["509ba6a40b32cb7486000002"]
b.as: []

test.rb

#!/usr/bin/env ruby

require "rubygems"
require "mongoid"

Mongoid.configure do |config|
  config.connect_to("mongoid_sandbox")
end

class A
  include Mongoid::Document

  has_and_belongs_to_many :bs, inverse_of: :as
end

class B
  include Mongoid::Document

  has_and_belongs_to_many :as, inverse_of: :bs
end

a = A.new

b = B.new

a.b_ids = [b.id]
puts "a.b_ids = [b.id]"

puts "a.b_ids: #{a.b_ids}"
puts "a.bs: #{a.bs.to_a}"

puts "b.a_ids: #{b.a_ids}"
puts "b.as: #{b.as.to_a}"

puts

a.bs = [b]
puts "a.bs = [b]"

puts "a.b_ids: #{a.b_ids}"
puts "a.bs: #{a.bs.to_a}"

puts "b.a_ids: #{b.a_ids}"
puts "b.as: #{b.as.to_a}"