Dynamic hash field in Mongoid using strong parameters

Question

So there doesn't appear to be any clean way to generically allow Hash field with strong parameters. This may of course be a strong parameters issue but I'm curious if there is a workaround. I have a model with some fields...

field :name, type: String
field :email, type: String
field :other_stuff, type: Hash, default: {}

Now I could just permit everything:

params.require(:registration).permit!

But that isn't really a great idea and what I'd like to do is something like...

params.require(:registration).permit(:name, :email, { other_stuff: {} })

However this doesn't seem to be possible with strong parameters, it isn't possible to just whitelist a hash as a property (yay for SQL centric ActiveRecord APIs!). Any ideas how this might be done, or is my best bet to submit a Rails patch to allow for this scenario.

Answer 1

Ok, after researching this, I found an elegant solution that I will start using too:

params.require(:registration).permit(:name).tap do |whitelisted|
  whitelisted[:other_stuff] = params[:registration][:other_stuff]
end

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

Answer 2

If necessary nested attributes can also be permitted as follows:

def create_params
  params[:book]["chapter"].permit(:content)
end

Answer 3

For a field that allows nested hashes, I use the following solution:

def permit_recursive_params(params)
  params.map do |key, value|
    if value.is_a?(Array)
      { key => [ permit_recursive_params(value.first) ] }
    elsif value.is_a?(Hash) || value.is_a?(ActionController::Parameters)
      { key => permit_recursive_params(value) }
    else
      key
    end
  end
end

To apply it to for example the values param, you can use it like this:

def item_params
  params.require(:item).permit(values: permit_recursive_params(params[:item][:values]))
end