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Pluck multiple columns/attributes in Rails 3, 4, 5, and can return data as hash instead of only array. Also supports Mongoid.

This Gem stands on the shoulders of this article: Plucking Multiple Columns in Rails 3. And modified to support not only Rail 3.

If you have a Rails 3 project, and want to pluck not only one column, feel free to use this gem and no need to worry about upgrading to Rails 4, 5 in the future will break this.


Add this line to your application's Gemfile:

gem 'pluck_all'

And then execute:

$ bundle

Or install it yourself as:

$ gem install pluck_all


pluck to array

Behaves the same as the Rails 4 pluck, but you can use it in Rails 3

User.where('id < 3').pluck_array(:id, :account)
# => [[1, 'account1'], [2, 'account2']]

pluck to hash

Similar to pluck_array, but return hash instead.

User.where('id < 3').pluck_all(:id, :account)
# => [{"id"=>1, "account"=>"account1"}, {"id"=>2, "account"=>"account2"}]

User.where('id < 3').pluck_all('id, account AS name')
# => [{"id"=>1, "name"=>"account1"}, {"id"=>2, "name"=>"account2"}]

Support Mongoid

class User
  include Mongoid::Document

  field :name, type: String
  field :age, type: Integer

User.pluck_all(:name, :age)
# => [
#      {'name' => 'Pearl Shi'   , 'age' => 18},
#      {'name' => 'Rumble Huang', 'age' => 20},
#      {'name' => 'Khiav Reoy'  , 'age' => 20},
#    ]


Compare with map and as_json

pluck_all return raw hash data without loading a bunch of records, in that having better performace than using map and as_json. The following is the benchmark test on 191,093 users, where users table have 51 columns.

                                       user     system      total        real
map                               36.110000  61.200000  97.310000 ( 99.535375)
select + map                      10.530000   0.660000  11.190000 ( 12.550974)
select + as_json                  49.040000   1.120000  50.160000 ( 55.417534)
pluck_all                          3.310000   0.100000   3.410000 (  3.527775)

test script

Compare with pluck_to_hash gem

pluck_all has better performace since it uses raw hash data from ActiveRecord::Base.connection.select_all, while pluck_to_hash uses pluck method, which calls ActiveRecord::Base.connection.select_all and transfers the raw hash data to array format, and then transfer the data to hash format again. The following benchmark test uses same datebase as above.

                                       user     system      total        real
pluck_to_hash                      2.960000   0.130000   3.090000 (  3.421640)
pluck_all                          2.160000   0.120000   2.280000 (  2.605118)

test script

Other Support

Support Pluck Carrierwave Uploader (if you use carrierwave)

User.where(xxx).pluck_all(:profile_pic).map{|s| s['profile_pic'] }

is the same as


If the uploader use something like:, You may have to send these columns manually:

User.where(xxx).cast_need_columns(%i(id, name)).pluck_all(:id, :name, :profile_pic).map{|s| s['profile_pic'] }


After checking out the repo, run bin/setup to install dependencies. Then, run rake test_active_record or rake test_mongoid to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.