attr_accessible breaks nested model attributes

If a model with has_many and accepts_nested_attributes_for also has attr_accessible, then you cannot use nested model attributes to create instances of the child model in the parent model.

I confirmed this using a testbed based on the Railscast for Nested Model Forms. Survey accepts_nested_attributes_for :questions. I then run the following code:

Survey.create({:name => "test", :questions_attributes => [ { :content => "a"} ] }).questions.size

If Survey does not have attr_accessible :name, then the result of this statement is 1. If it does have it, then the result is zero.

I've tested this in Rails 2.3.2 and Rails 3, and got the same behavior.

(I originally described this on Stack Overflow)

Craig Walker