Rails - Mar 2009 - order by number of occurances in a has_many relationship

I can''t seem to find anything to explain how I might be able to order a
list according to the number of occurrences of an item in a has_many
relationship, so maybe someone could help me learn how...

To illustrate, imagine I have the following situation:

I have one table with details for a number of people, and one table of
items. Each item belongs to one person and each person can have may
items.

In my view I have something like this:

<% for person in @people %>
  <tr>
    <td><%=h person.name %></td>
    <td><%=h person.items.count %></td>
  </tr>
<% end %>

I can get the list to order by the id/name etc. of the people, but I
really want to order it by the number of items belonging to each person,
something like so:

@people = Person.find(:all, :order => ''person.items.count
desc'')

except that this brings up an ''unknown column'' error.

Any ideas for getting around this?
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On Mon, Mar 9, 2009 at 11:42 AM, Sandy Thomson
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> @people = Person.find(:all, :order => ''person.items.count
desc'')
>
> except that this brings up an ''unknown column'' error.
>
> Any ideas for getting around this?
@people.sort!{ |a,b| a.items.count <=> b.items.count }



-- 
Greg Donald
http://destiney.com/

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Greg Donald wrote:
> On Mon, Mar 9, 2009 at 11:42 AM, Sandy Thomson
> <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:
>> @people = Person.find(:all, :order => ''person.items.count
desc'')
>>
>> except that this brings up an ''unknown column'' error.
>>
>> Any ideas for getting around this?
> 
> @people.sort!{ |a,b| a.items.count <=> b.items.count }
> 
> 
> 
> --
> Greg Donald
> http://destiney.com/
Cheers for that Greg, it works fine but is a little heavy on the 
database (predictable I guess). However, this has steered me towards 
creating a counter cache in the people table, which I hadn''t considered
before and which cuts down hugely on the number of SQL queries.

Thanks!
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