# File actionpack/lib/action_view/helpers/form_helper.rb, line 1803 def emitted_hidden_id? @emitted_hidden_id ||= nil end
This method keeps track of whether a hidden id field needs to be created when the form builder is generating fields for a nested model. It gets set to true by #hidden_field when that method is used to create a field named ‘id’.
Here’s an example of what this can be useful for: http://railsforum.com/viewtopic.php?id=39640