Dependency on the gems loading order

[r7kamura]

elasticsearch-model only loads the corresponding extensions if the kaminari or will_paginate has already been loaded when it is loaded.

elasticsearch-rails/elasticsearch-model/lib/elasticsearch/model.rb

Lines 57 to 62 in 41f4291

	case
	when defined?(::Kaminari)
	Elasticsearch::Model::Response::Response.__send__ :include, Elasticsearch::Model::Response::Pagination::Kaminari
	when defined?(::WillPaginate)
	Elasticsearch::Model::Response::Response.__send__ :include, Elasticsearch::Model::Response::Pagination::WillPaginate
	end

In a typical Rails application, gems are usually loaded with Bundler.require in config/application.rb, which means that unless those gems are listed in the Gemfile before elasticsearch-model, it won’t work as intended.

The fact that behavior changes depending on the order of gems makes it very confusing and prone to misunderstandings. I think it would be much better to improve it by using mechanisms like ActiveSupport.on_load hooks so that it no longer depends on the load order.

For example, the Bundler/OrderedGems rule from rubocop-rails, commonly used in Rails development, enforces sorting gems alphabetically in the Gemfile. Following this, elasticsearch-model would appear before kaminari or will_paginate, making this issue a frequent occurrence.

• https://docs.rubocop.org/rubocop/cops_bundler.html#bundlerorderedgems