How to use ActiveModel callbacks on class methods?

Question

I want to execute a method before each class method. Is it possible to do this using ActiveModel callbacks or do i have to use metaprogramming ?

I tried :

class Image
  extend ActiveModel::Callbacks

  define_model_callbacks :create
  before_create :set_base_uri

  def self.create
    run_callbacks :create do
      ..my_code..
    end
  end

  def set_base_uri
    ..my_code..
  end
end

When i call Image.create i get

undefined method `run_callbacks' for Image:Class

The same code works if i change create to an instance method. I looked at the documentation but they don't mention class methods, does ActiveModel support class methods callbacks ?

Answer 1

i don't think callback can work, as the callback method is invoked in the instance level. Use an alias_method may works.