need help with nested forms and habtm

Hi,

I'm currently stuck with a problem I just can't find a clever solution
for. I checked every tutorial, issuetracker, API reference I could
find but found nothing to "enlighten" me --> I desperately need your
help :-).

My Question is: is it possible to use nested forms for habtm
associations?

--> Here some more info about what I wanted to do and what failed

### Basic info ###
I've got following model associations:
Customer
   has_many :inquiries
   attr_accessible :inquiry_ids
   accepts_nested_attributes_for :inquiries

Inquiry
   belongs_to :customer
   has_and_belongs_to_many :machines
   accepts_nested_attributes_for :machines
   attr_accessible :machine_ids

Machine
   has_and_belongs_to_many :inquiries

I'm on Rails 2.3.5 and formtastic 0.9.7

### What I want ###
I wanted to build a nested form (using formtastic + haml), so a User
could enter his data and create an inquiry regarding several machines
(he put into a cart in advance)

so I set up this:
- semantic_form_for @customer do |form|
     - form.inputs do
       = form.input :companyname
       = form.input :salutation, :as => :radio, :label => "Gender",
:collection => [["Mister", "m"], ["Mrs.", "f"]]
       = form.input :first_name
       = form.input :last_name
       = form.input :street
       = form.input :zip
       = form.input :city
       = form.input :phone
       = form.input :mobile
       = form.input :fax
       = form.input :email

     - form.inputs :for => [:inquiries, @inquiries] do |inquiry_form|
       = inquiry_form.input :text, :hint => t("inquiryinfo")
       - inquiry_form.inputs :for => [:machines, @machines] do

machine_form|

         = machine_form.input :id, :as => :hidden
     = form.commit_button :label => t("send")

### PROBLEM ###
- the form renders fine for the customer and inquiry fields --> OK!
- the form renders the hidden field only for the FIRST machine in my
@machines collection (and there is definitly more then 1 machine in
the collection, I already checked this with array size and by
outputting the machines in a for each loop)

### QUESTION ###
- Did I miss some configuration?
- are nested forms not usable for habtm associations???
--> if so, how could I handle my "use case" in the controller?

I'd be sooo happy I any of you could help me out with this.....I'm
really lost :frowning:
P.S. Sorry for my English, it's not my native tongue :slight_smile: