Get values of a single attribute from an instance variable

Question

I have an instance variable @items which i get from doing@items = Item.all inside a controller action. The Item class looks like this:

class Item < ActiveRecord::Base
  attr_accessible :weight, :color, :price
  validates :color, presence: true
  validates :price, presence: true
end

What i would like to do is to get the values of the :id attributes of all the items in@items the controller action in which i'm trying to get the ids looks like this:

def get_item_ids
  @items = Item.all
  item_ids = ??? ## i'm stuck here
end

How can get item_ids as an array of :id attributes of items inside @items ?

Answer 1

If you only need the ids and not the entire object itself, MrYoshiji's answer is best:

item_ids = Item.scoped.pluck(:id)

If, however, you already have a collection of items in @items then you can do this:

item_ids = @items.map(&:id)