Rails - Jul 2006 - Getting joined collections on a form

Greetings, I''m looking for suggestions on how to simplify getting
customer
addresses on a form:

I''m jumping between controller and view several times; alternating
between
rhtml and rjs, in order to display customers and their addresses on an
invoicing form. It''s very messy.

I have a one to many relationship between Customer and Addresses, each
customer has one or more addresses. The user opens the Invoice form and
selects from a list of customers which in turn populates and displays a list
of that customer''s addresses.

It works like this:

1) The Invoice controller receives a new request and renders the new.rhtmlform:

/invoices/new

def new
    @invoice = Invoice.new
    @customers = Customer.find(:all, :order => "name")
end

new.rhtml

<% form_for :invoice, @invoice, :url => { :action => "create"
} do |f| %>
        Customer:
        <%            collection_select(:invoice, :customer_id, @customers,
:id,
:name,
            {:include_blank => true},
            {:onchange => remote_function(:url => { :action =>
"get_customer"},
                :with => "''invoice_customer_id=''+
$F(''invoice_customer_id'')")}
            )
        %>
        <div id="customer"></div>
    <%= hidden_field :invoice, :customer_id, :value => "" %>
    <%= submit_tag ''Add Invoice'' %>
<% end %>

2) The onchange event calls the controller action get_customer, which does a
find on the selected customer_id. It also gets the address collection and
then Rails renders the customer.rjs which in turn inserts customer.rhtml

/invoices/get_customer/1

def get_customer
    @customer = Customer.find(params[:invoice_customer_id])
    @addresses = Customer.find(params[:invoice_customer_id]).addresses
end

customer.rjs

page[:customer].replace_html :partial =>
''customers/customer'', :object =>
@customer
page[:customer].visual_effect :highlight

customer.rhtml

    <%        collection_select(:invoice, :address_id, @addresses, :id,
:street,
        {:include_blank => true},
        {
        :onchange => remote_function(:url => { :action =>
"get_address"},
            :with => "''invoice_address_id=''+
$F(''invoice_address_id'')")
        })
    %>

3) Next a similar pattern occurs for addresses...

Back we go to the controller with the action get_address and then render
address.rjs and then address.rhtml. It''s annoying because I have other
values to gather on this form that also have multiple joins.

I suspect the culprit of this complexity is the onchange event and
remote_function calls. I''ve considered calling a local javascript
function
to expose the selected customer''s addresses -- they are available via
the
@customer object thanks to the has_many relationship --- however, I
haven''t
figured out how to do that.

Possibly a entirely different solution exists. Your thoughts and ideas are
gratefully appreciated!
--Dave
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