AR not save updated PostgreSQL arrays

[nleo]

pry> model.array << element
pry>  model.save
   (0.4ms)  BEGIN
   (0.4ms)  COMMIT
=> true

unless File.exist?('Gemfile')
  File.write('Gemfile', <<-GEMFILE)
    source 'https://rubygems.org'
    gem 'rails', '4.1.0'
    gem 'pg'
  GEMFILE

  system 'bundle'
end

require 'bundler'
Bundler.setup(:default)

require 'active_record'
require 'minitest/autorun'
require 'logger'
require 'pry'

ActiveRecord::Base.establish_connection adapter: "postgresql",
  host: "localhost",
  user: "postgres",
  database: "test"

ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  execute 'drop table if exists bars'
  create_table :bars
  execute "alter table bars add column array_of_varchar varchar(255)[]"
end

class Bar < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_postgresql_save_array
    bar = Bar.create! array_of_varchar: []
    bar.array_of_varchar << 'Sample string'
    bar.save!
    bar.reload
    assert_equal 'Sample string', bar.array_of_varchar[0]
  end
end

[nleo]

#not work
model.update! array: model.array.push(element)
#works
model.array << element
model.array_will_change!
model.save!

[senny]

@nleo this is currently expected behavior. Rails does not know when you change the object itself. You need to use the attribute writer array_attribute= or the array_attribute_will_change! method.

[senny]

It's also the same as with #6127

[nleo]

@senny I agree it maybe overwork to watch array changes, just notice that as user then I say to system update! and specify attribute and value I expect to overwrite columne whenether it changed or not.