Rails - Sep 2006 - add a column count(id) to the select statement, rail way

I would like to do something like this:
SELECT *,count(ID) FROM downloads GROUP BY file_path ORDER BY user_id LIMIT 10;

I know it can be done with find_by_sql, but don't know if that can be
done by just find.

Or is there better Rails way to do this?

Thanks.

-- 
Igor MILOVANOVIÆ
http://f13o.pletisan.rs.ba/blog/

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I think you risk running 2 queries if you do it the rails way of
Model.count().
Up to you really.  Its probably better to do a custom find_by_sql to limit
the queries you run against your DB.

Adam

On 9/13/06, Igor Milovanović <pletisan.list@gmail.com>
wrote:
>
> I would like to do something like this:
> SELECT *,count(ID) FROM downloads GROUP BY file_path ORDER BY user_id
> LIMIT 10;
>
> I know it can be done with find_by_sql, but don't know if that can be
> done by just find.
>
> Or is there better Rails way to do this?
>
> Thanks.
>
> --
> Igor MILOVANOVIÆ
> http://f13o.pletisan.rs.ba/blog/
>
> >
>
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> I would like to do something like this:
> SELECT *,count(ID) FROM downloads GROUP BY file_path ORDER BY 
> user_id LIMIT 10;
> 
> I know it can be done with find_by_sql, but don''t know if 
> that can be done by just find.
> 
> Or is there better Rails way to do this?
If by "Rails way" you mean something built in to ActiveRecord, then
you''re talking about counter_cache.

class Download < ActiveRecord::Base
  belongs_to :product, :counter_cache => true
end

Then in your product table, you would have a downloads_count column
(int, default of 0).

When you do that you''ll be able to access
  product.downloads.size

*WARNING* I recall there being a prior thread talking about a bug in
save() that blows away the count, or something like that. So I don''t
know if this solution is broken or not at this point.

- Mark.


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Thanks for replies, I will have a look.
But this find_by_sql solution is working like a charm for me...
So, I might just leave it that way...

On 9/13/06, Thomas, Mark - BLS CTR <Thomas.Mark@bls.gov> wrote:

-- 
Igor MILOVANOVIÆ
http://f13o.pletisan.rs.ba/blog/

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