method
to_ary
rails latest stable - Class:
ActiveRecord::Core::ClassMethods
to_ary()public
+Array#flatten+ will call #to_ary (recursively) on each of the elements of the array, and then rescues from the possible NoMethodError. If those elements are +ActiveRecord::Base+‘s, then this triggers the various method_missing's that we have, which significantly impacts upon performance.
So we can avoid the method_missing hit by explicitly defining #to_ary as nil here.
See also tenderlovemaking.com/2011/06/28/til-its-ok-to-return-nil-from-to_ary.html