Find corrupted MongoDB embedded items inside multiple collections. Code from @macreery.

find_corrupted_mongoid_embedded_items.rb

summary_totals = {}
summary_totals.default = 0
count = 0
{
  Collection => :items,
  Artwork => :images
}.each do |coll, orderable_subcoll|
  coll.all.each do |item|
    $stdout.write "." if count % 1000 == 0
    count += 1
    if (item.collection.find(_id: item._id).first[orderable_subcoll.to_s] || []).any? { |doc_subitem| (doc_subitem || {})['_id'].nil? }
      puts "\n#{coll}:#{item._id}\n" 
      summary_totals[coll] += 1
    end
  end
end
puts "\n\n === SUMMARY ==="
summary_totals.each do |k, v|
  puts "#{k}: #{v} bad documents"
end