Tengo un recurso anidado singular como este:

  map.resources :bookings, :member => { :rate => :post } do |booking|
    booking.resource :review
  end

Dándome estas rutas:

   new_booking_review GET    /bookings/:booking_id/review/new(.:format)      {:controller=>"reviews", :action=>"new"}
  edit_booking_review GET    /bookings/:booking_id/review/edit(.:format)     {:controller=>"reviews", :action=>"edit"}
       booking_review GET    /bookings/:booking_id/review(.:format)          {:controller=>"reviews", :action=>"show"}
                      PUT    /bookings/:booking_id/review(.:format)          {:controller=>"reviews", :action=>"update"}
                      DELETE /bookings/:booking_id/review(.:format)          {:controller=>"reviews", :action=>"destroy"}
                      POST   /bookings/:booking_id/review(.:format)          {:controller=>"reviews", :action=>"create"}

Intenté esto:

<% form_for [@booking, @review] do |f| %>

Lo que devolvió este error:

undefined method `booking_reviews_path' for #<ActionView::Base:0x10572b888>

Con mi controlador de comentarios

  def new
    @review = Review.new
    @booking = Booking.find(params[:booking_id])
  end

Pero esto funciona ... si enumero la URL explícitamente ...

<% form_for :review, :url => booking_review_path(@booking) do |f| %>

No es gran cosa ... pero me pregunto qué estoy haciendo mal.

Gracias