gistfile1.rb

#!/usr/bin/env ruby
# encoding: utf-8

require 'bundler'
Bundler.setup(:default)

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

ActiveRecord::Base.establish_connection(adapter: 'postgresql', encoding: 'unicode', host: '127.17.0.3', pool: 5, username: 'postgres')
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :json_models do |t|
    t.json 'payload'
  end unless table_exists?(:json_models)
end

class JsonModel < ActiveRecord::Base
end

class BugTest < Minitest::Test
  def test_distinct_json
    # this works
    JsonModel.select("DISTINCT ON (json_models.id) json_models.*").to_a

    # this does not
    JsonModel.distinct.to_a
  end
end