I'm new to rails and working on a rails app and I'm stuck pondering this issue.

I have three models

class product < ActiveRecord::Base

attr_accessible :name, :issn, :category

validates_presence_of :name, :issn, :category
validates_numericality_of :issn, :message => "has to be a number"

has_many :user_products
has_many :users, :through => :user_products

end

class UserProduct < ActiveRecord::Base

attr_accessible :price, :category

validates_presence_of :price, :category validates_numericality_of :price, :message => "has to be a number"

belongs_to :user belongs_to :product

end

class user < ActiveRecord::Base

# devise authentication here

# Setup accessible (or protected) attributes for your model attr_accessible :email, :password, :password_confirmation, :remember_me

has_many :user_products has_many :products, :through => :user_products

end

here is my new.html.erb

<div class="MainBodyWrapper">
    <div class="span8">

       <div id="listBoxWrapper">          
        <fieldset>
         <%= form_for(@product, :html => { :class => "form-inline" }, :style => "margin-bottom: 60px" ) do |f| %>


            <div class="control-group">
              <label class="control-label" for="name">name</label>
              <div class="controls">

                <%= f.text_field :price, :class => 'input-xlarge input-name', :id => "name" %>

              </div>
            </div>

            <div class="listingButtons">
             <button class="btn btn-info"></i>Add</button>
          <a class="btn">Upload Pictures (anytime)</a>    

          </div>

       </fieldset>
         </div>
       </div>

There are reasons why I want to setup the models this way.

So the question is this: I want the user to enter the info for the product in the form but it also involves putting in the price of the product which exists in a different model/table (user_product) that is associated with product. How can I do this? You can see that my form_for uses @product.

Any help will be appreciated.