Nested attributes unpermitted parameters

Seems there is a change in handling of attribute protection and now you must whitelist params in the controller (instead of attr_accessible in the model) because the former optional gem strong_parameters became part of the Rails Core.

This should look something like this:

class PeopleController < ActionController::Base
  def create
    Person.create(person_params)
  end

private
  def person_params
    params.require(:person).permit(:name, :age)
  end
end

So params.require(:model).permit(:fields) would be used

and for nested attributes something like

params.require(:person).permit(:name, :age, pets_attributes: [:id, :name, :category])

Some more details can be found in the Ruby edge API docs and strong_parameters on github or here

or you can simply use

def question_params

  params.require(:question).permit(team_ids: [])

end

Actually there is a way to just white-list all nested parameters.

params.require(:widget).permit(:name, :description).tap do |whitelisted|
  whitelisted[:position] = params[:widget][:position]
  whitelisted[:properties] = params[:widget][:properties]
end

This method has advantage over other solutions. It allows to permit deep-nested parameters.

While other solutions like:

params.require(:person).permit(:name, :age, pets_attributes: [:id, :name, :category])

Don't.

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Source:

https://github.com/rails/rails/issues/9454#issuecomment-14167664

From the docs

To whitelist an entire hash of parameters, the permit! method can be used

params.require(:log_entry).permit!

Nested attributes are in the form of a hash. In my app, I have a Question.rb model accept nested attributes for an Answer.rb model (where the user creates answer choices for a question he creates). In the questions_controller, I do this

  def question_params

      params.require(:question).permit!

  end

Everything in the question hash is permitted, including the nested answer attributes. This also works if the nested attributes are in the form of an array.

Having said that, I wonder if there's a security concern with this approach because it basically permits anything that's inside the hash without specifying exactly what it is, which seems contrary to the purpose of strong parameters.