WARNING: Can't mass-assign protected attributes

Question

I get this error \"WARNING: Can\'t mass-assign protected attributes: races_attributes\" , when following this http://railscasts.com/episodes/196-nested-model-form-part-1 on rail

Answer 1

attr_accessible specifies that you can not mass-assign attributes, using save method, for example. So, if you change an attribute that is not defined with attr_accessible, you will get a warning because it will not actually be saved in the database.

Answer 2

Shorter than using attr_accessible, safer than using whitelist_attributes: attr_protected

Just indicate the protected attributes, and Rails will infer that all others can be mass-assigned:

class MyClass < ActiveRecord::Base
  attr_protected :id
end

(I always have way more attributes that I want mass-assigned than the ones I want protected.)