Creating nested form in Rails 3.1 - ruby-on-rails-3

Question

I am trying to render a partial which I have set up as the following. I have am also trying to create a nested form whereby I have included accepts_nested_attributes_for :user in my hospital_bookings model. I seem to be getting the following error:
NameError in Rota_days#index
Showing
C:/Users/home/Desktop/Portal/app/views/rota_days/index.html.erb
where line #31 raised:
undefined local variable or method `hospital_booking' for
which is pointing to the following line <%= render :partial => "booking_dialog", :locals => { :booking => hospital_booking.new } %> of my index.html.erb as shown below. I thought it was something to do with my pluralization. By changing hospital_bookings.new to hospital_booking.new but this did not work
_booking_dialog.html.erb
<%= form_for booking do |f| %>
<%= f.fields_for :user do |f| %>
<br/>
<%= f.label :name %>
<br/>
<%= f.text_field :name %>
<%= f.hidden_field :hospital_id %>
<%= f.hidden_field :id unless booking.new_record? %>
<div class="actions">
<%= f.submit %>
</div>
<% end %>

Answer 1

hospital_booking.new is nonsensical: you have no local variable named hospital_booking. If you want a new instance of the HospitalBooking model, then you want HospitalBooking.new.
So:
<%= render :partial => "booking_dialog", :locals => { :booking => HospitalBooking.new } %>
Update (from the comments)
In the booking_dialog form partial, you need to put the name attribute on the associated user record inside a fields_for block, to distinguish it from the fields for the parent (booking):
<%= form_for booking do |f| %>
<%= fields_for :user do |user_fields| %>
<%= user_fields.label :name %>
<%= user_fields.text_field :name %>
<% end %>
<%= f.hidden_field :hospital_id %>
<%= f.hidden_field :id unless booking.new_record? %>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
p.s. it seems very strange that you have a hidden field for the :id in here. You shouldn't need that.