Set value using Jquery in Select List on Nested Form

Rails
#1

Hi, I am new to Rails.

Been struggle finding solution for soooo long. Too long I think.

I have nested form:


<%= f.fields_for :items do |i| %>
<%= render ‘item_fields’, :f => i %>
<% end %>

<%= link_to_add_association ‘+ product’, f, :items %>

with item_fields partial:

<%= f.select :product_id,
Product.all.collect {|p| [p.name, p.id,
{‘data-unit_cost’=>p.sell_price},
{ class: ‘product-chosen’, id:
‘product-select’} %>

<%= f.input :sell_price,
id: “price-input” %>

<%= link_to_remove_association image_tag(“delete.png”), f
%>

and coffee script:
$("#product-select").change ->
unit_cost = $(’#product-select :selected’).data(‘unit_cost’)
$(’#price-input’).val(unit_cost)

The idea is everytime product is selected, it store sell_price as value
for
sell_price input.

What I get is:

  1. If I use ‘product-select’ and ‘price-input’ as class, the result is,
    the
    second row will duplicating the value from first row.

https://lh3.googleusercontent.com/-NJC-6R77HFU/U2jinN52rXI/AAAAAAAAAA4/4H86Nfc8a_w/s1600/duplicate.png

  1. If ‘product-select’ and ‘price-input’ as id, the second row value is
    empty.

https://lh3.googleusercontent.com/-w1PPRLPdtsA/U2jju-lz40I/AAAAAAAAABE/Qkh69CcM5mc/s1600/Screen+Shot+2014-05-06+at+8.28.24+PM.png

Gem I use: Cocoon, Simple_form, Chosen. The behaviour is the same
without
using Simple_form and Chosen gems.

I see that fields_for block will create hidden_field_id which I think
could
solve this, but I don’t know how to access it and use it in script.

Any help would be appreciated.