Rails - Sep 2005 - Populating an array - put code in view or controller?

Morning all,

I''ve come across a frustrating and somewhat odd problem. If I put the
code:

@sub_categories - SubCategory.find(:all)

into a form partial, @sub_categories works when used in a
collection_select form helper. However, if I put that code in the
controller, I''m told given a "You have a nil object..." error
message.

I reckon the code belongs in the controller, rather than the partial
but, no matter how many examples I look at, I don''t seem able to fix
the problem.

The relevant part of my controller is simple enough and as follows:

class ProductController < ApplicationController

  model :SubCategory

  def edit
      @product = Product.find(params[:id])
      @sub_categories = SubCategory.find(:all)
  end

end

My partial looks like:

<%= error_messages_for ''product'' %>

<!--[form:product]-->
<p><label for="product_name">Name</label><br/>
<%= text_field ''product'', ''name'' 
%></p>

<p>Category<br />

<p><label
for="sub_category_name">Sub-category</label><br/>
<%= collection_select(''product'',
''sub_category_id'', @sub_categories,
''id'', ''name'') %>
</p>

<p><label for="product_created_at">Created
at</label><br/>
<%= datetime_select ''product'',
''created_at''  %></p>

<p><label for="sub_category_updated_at">Updated
at</label><br/>
<%= datetime_select ''product'',
''updated_at''  %></p>
<!--[eoform:product]-->

I feel as though I must be missing something pretty fundamental about
Rails or Ruby. I''ve tried looking for examples of other people having
similar problems but I''m not entirely sure what terms to search for.

Thanks in advance, if anyone''s able to offer some advice.

--
Matthew Revell
www.understated.co.uk

Matthew Revell wrote:
>   model :SubCategory
This line is probably not needed, and if it is it should
refer to the model filename rather than the class name:

	model :sub_category

-- 
We develop, watch us RoR, in numbers too big to ignore.