What is that for?

Extends ActiveRecord by adding pluck_to_hash method that returns array of hashes instead of array of arrays. Useful when plucking multiple columns for rendering json or you need to access individual fields in your view for example.

Supports pluck_to_struct since version 0.3.0. pluck_to_struct returns an array of structs.

Installation

Add this line to your application's Gemfile:

gem 'pluck_to_hash'

And then execute:

$ bundle

Or install it yourself as:

$ gem install pluck_to_hash

Usage

Usage is similar to ActiveRecord.pluck, for example

Post.limit(2).pluck_to_hash(:id, :title)
#
# [{:id=>213, :title=>"foo"}, {:id=>214, :title=>"bar"}]
#

Post.limit(2).pluck_to_hash(:id)
#
# [{:id=>213}, {:id=>214}]
#

Or use the shorter alias pluck_h

Post.limit(2).pluck_h(:id)
#
# [{:id=>213}, {:id=>214}]
#

Supports select alias

User.pluck_to_hash(:id, 'created_at::date as my_date', 'created_at::time as my_time')
#
# [{:id=>23, :my_date=>Fri, 11 Jul 2014, :my_time=>2000-01-01 07:54:36 UTC},
#  {:id=>2, :my_date=>Tue, 01 Jul 2014, :my_time=>2000-01-01 14:36:15 UTC}]
#

Accepts block parameter

User.pluck_to_hash(:id, :title) do |user_hash|
  ...
end

Allows specifying the type of hash. Defaults to HashWithIndifferentAccess

User.pluck_to_hash(:id, :title, hash_type: CustomHash) do |custom_hash|
  ...
end

Using `pluck_to_struct`

posts = Post.limit(2).pluck_to_struct(:id, :title)
#
# [#<struct id=1, title="foo">, #<struct id=2, title="bar">]
#

posts.first.id
# 1

posts.first.title
# "foo"

or use the shorter alias pluck_s

posts = Post.limit(2).pluck_s(:id, :title)
#
# [#<struct id=1, title="foo">, #<struct id=2, title="bar">]
#

Supports block parameter as well

Post.limit(2).pluck_to_struct(:id, :title) do |post_struct|
  puts post_struct.title
end

Allows specifying the type of struct. Defaults to standard Struct.

Post.limit(2).pluck_to_struct(:id, :title, struct_type: OtherStructType) do |post_struct|
  puts post_struct.title
end

Using with Sinatra or other non-rails frameworks without ActiveSupport

Use version 0.1.4 that removes ActiveSupport dependency. HashWithIndifferentAccess is not used in that case.

Why not `ActiveRecord.select` or `ActiveRecord.as_json`?

Here are results of "benchmark" tests performed on MacBook Air. Each method did 10 runs, rejected the 2 highest and 2 lowest times and average the remaining 6. Ran these tests on about 40,000 records. We notice that pluck_to_hash is almost 4x faster than select and about 8x faster than as_json. As with all the "benchmarks", you should take these results with a pinch of salt!

# Node.pluck_h(:id, :title)
# Node.select(:id, :title).to_a
# Node.select(:id, :title).as_json

                    user     system      total        real
pluck_to_hash   0.145000   0.005000   0.150000 (  0.164836)
select          0.566667   0.010000   0.576667 (  0.590911)
as_json         1.196667   0.010000   1.206667 (  1.222286)

Contributing

Fork it ( https://github.com/girishso/pluck_to_hash/fork )
Create your feature branch (git checkout -b my-new-feature)
Commit your changes (git commit -am 'Add some feature')
Push to the branch (git push origin my-new-feature)
Create a new Pull Request

Licence

MIT License