Simple example of how to remove a key from a mongo document

remove_key.rake

namespace :harmony do
  desc "Munges the data"
  task :munge => :environment do
    docs_with_publish = Item.collection.find({'publish' => {'$exists' => true}}).to_a
    
    puts "Item count: #{Item.count}"
    puts "Items with publish key: #{docs_with_publish.size}"
    
    docs_with_publish.each do |hash|
      hash.delete('publish')
      Item.collection.save(hash)
    end
    
    activities_with_thumbnail = Activity.collection.find({'source.thumbnail' => {'$exists' => true}}).to_a
    
    puts "Activity count: #{Activity.count}"
    puts "Activites with thumbnail: #{activities_with_thumbnail.size}"
    
    activities_with_thumbnail.each do |hash|
      hash['source'].delete('thumbnail')
      Activity.collection.save(hash)
    end
  end
end