Pluck multiple attributes in Rails 3. Also support in Rails 4, and Rails 5

This Gem standing on the shoulders of this article. And modify it 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.

Code Quality Rank: L5
Monthly Downloads: 19,446
Programming language: Ruby
License: MIT License
Tags: ORM/ODM Extensions     Pluck     Rails     Active Record    
Latest version: v2.0.4

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Pluck multiple columns/attributes in Rails 3, 4, 5, 6, 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, 6 in the future will break this.


  • Ruby 2.2 ~ 2.7
  • Rails 3.2, 4.2, 5.0, 5.1, 5.2, 6.0


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 #pluck method, but you can use it to pluck multiple columns in Rails 3

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

pluck to hash

Similar to #pluck method, but return array of hashes 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"}]

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 by benchmark-ips and limit 100 in each iteration:

Warming up --------------------------------------
                 map     1.000  i/100ms
        select + map    28.000  i/100ms
    select + as_json     7.000  i/100ms
           pluck_all    54.000  i/100ms
Calculating -------------------------------------
                 map     14.230  (± 0.0%) i/s -     72.000  in   5.065349s
        select + map    281.638  (± 4.6%) i/s -      1.428k in   5.081216s
    select + as_json     73.241  (± 4.1%) i/s -    371.000  in   5.076235s
           pluck_all    539.057  (± 6.7%) i/s -      2.700k in   5.034858s

           pluck_all:      539.1 i/s
        select + map:      281.6 i/s - 1.91x  slower
    select + as_json:       73.2 i/s - 7.36x  slower
                 map:       14.2 i/s - 37.88x  slower

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 shows the performance difference:

                                       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)

Tested by benchmark-ips and limit 1000 in each iteration:

Warming up --------------------------------------
       pluck_to_hash     7.000  i/100ms
           pluck_all     9.000  i/100ms
Calculating -------------------------------------
       pluck_to_hash     84.526  (± 4.7%) i/s -    427.000  in   5.065792s
           pluck_all     95.133  (± 4.2%) i/s -    477.000  in   5.021555s

           pluck_all:       95.1 i/s
       pluck_to_hash:       84.5 i/s - 1.13x  slower

See the test script for more details.

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: model.id, model.name 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 rubygems.org.


Bug reports and pull requests are welcome on GitHub at https://github.com/khiav223577/pluck_all. 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.

*Note that all licence references and agreements mentioned in the pluck_all README section above are relevant to that project's source code only.