add Array#pluck

Author: amancevice

README.md

@@ -191,6 +191,18 @@ Enable the helpers by requiring the `support` submodule:
 require 'yake/support'
 ```
 
+`Array` helpers:
+
+```ruby
+array = [{ a: 'b'}, { a: 'c' }, { a: 'd' }]
+
+array.pluck(:a)
+# => ["b", "c", "d"]
+
+array.to_dynamodb
+# => {:L=>[{:a=>{:S=>"b"}}, {:a=>{:S=>"c"}}, {:a=>{:S=>"d"}}]}
+```
+
 `Object` helpers:
 
 ```ruby

lib/yake/support.rb

@@ -6,6 +6,7 @@
 require 'uri'
 
 class Array
+  def pluck(key)  = map { |x| x[key] }
   def to_dynamodb = { L: map(&:to_dynamodb) }
 end
 

spec/support_spec.rb

@@ -75,6 +75,12 @@
     end
   end
 
+  context '#pluck' do
+    it 'should return a list of the plucked values' do
+      expect(([subject] * 3).pluck('fizz')).to eq(%w[buzz] * 3)
+    end
+  end
+
   context '#strict_encode64' do
     it 'should transform a Hash to a strict Base64-encoded string' do
       expect(subject.strict_encode64).to eq 'eyJmaXp6IjoiYnV6eiIsImphenoiOiJmdXp6IiwicmF6eiI6W3sibXRheiI6ImhhenoifV0sIndpenoiOnsia2l6eiI6ImthenoifX0='