[Rails] Re: Calculate methods on attr_accessor objects

[François Montel]

Thanks, Kevin. That didn't work, but it got me going in the right 
direction.

Through a bit of trial and error I discovered that contrary to what the 
AR rdoc says, count_by_sql accepts other methods than just COUNT.

So this works:

Item.count_by_sql("select sum(cost_unit * amount) from items")

Not very "rails like" though :-(. I should probably write a 
calculate_by_sql helper that accepts all the various calculate commands 
for those instances where you need more than just the sum of a single 
column or where that column doesn't exist.

Kevin Olbrich wrote:
> Something like this may work...
> 
> Item.sum(:select=>'(cost_unit + amount)')


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