chainable_scope.rb

# scope uses merge which looses conditions when chained on the same attribute
# see https://github.com/rails/rails/issues/7365 for the issue
# see https://github.com/rails/rails/blob/da5e5c5f779355a2e99e63a90612cbeaeb0fc986/activerecord/lib/active_record/relation/spawn_methods.rb#L35 for an explanation
# see https://github.com/rails/rails/commit/cd26b6ae7c1546ef8f38302661bbedf8cb487311 for a fix in Rails 4
# The workaround is to just use class methods - we wrap a dsl around just that
# Usage: extend ChainableScope in your ActiveRecord::Base derived class
module ChainableScope
  def chainable_scope name
    raise 'chainable_scope must be called with a block!' unless block_given?
    define_singleton_method name do |*args|
      yield(*args) or scoped
    end
  end
end

ActiveRecord::Base.extend(ChainableScope)