How to add a method to an activerecord collection?

Question

I would like to add a method to all collections for a specific model. Let\'s say I want to add the method my_complicated_averaging_method to the WeatherData collect

Answer 1

On Rails >= 4 you can to use where(nil) inplace of scoped

class Foo < ActiveRecord::Base  
  def self.bar
    where(nil).pluck(:id)
  end
end

Foo.where(id: [1, 2, 3]).order(:id).bar

And further, you can use #scope, for example:

class Foo < ActiveRecord::Base
  scope :bar, -> {where(nil).pluck(:id)}
end

Finally, You can write code like Foo.all.bar