[Rails] :index = nil

On here: http://api.rubyonrails.org/classes/ActionView/Helpers/FormHelper.html#method-i-check_box-label-Gotcha you see this code: %= fields_for project[invoice_attributes][], invoice, :index = nil do |form| % %= form.check_box :paid % ... % end % why are they using :index = nil in the

[Rails] index = nil params jumbled *sometimes*

My app has a timesheet, which is a collection of many TimeCards, based on a Date. I have one user that can create new TimeCards just fine, except on three associated Jobs. Each time he saves he gets a 500 error. Looking at the params, they come across jumbled and my processing method chokes: