rails/strong_parameters — pull request #20 by bjhess (2012-04-09 14:44:26+00:00)
Title: nil param value that expects a hash should return :key => nil

When a nil param value arrives in place of an expected hash, return :key => nil, not simply nil.

Prior:

(rdb:1) params
{"book"=>nil}
(rdb:1) params.permit(book: { genre: :type })
nil

Now:

(rdb:1) params
{"book"=>nil}
(rdb:1) params.permit(book: { genre: :type })
{"book"=>nil}