calculations on a virtual attribute...

rubyonrails-talk
1

I is possible to do calculations on a virtual attribute... such as sum, or count

I tried using the same as I would on a DB column but of course that doesn't work. ie. Pricelist.sum(:cyberguide)

I have a table with 2 fields, one with a price and the other with a condition then have a virtual attribute which does a calculation:

  def cyberguide     if condition <= 2       [price.pricehigh]     elsif condition == 3       [price.pricehigh * 0.9]     elsif condition == 4       [price.pricehigh * 0.5]     elsif condition == 5       [price.pricehigh * 0.25]     elsif condition == 6       [price.pricehigh * 0.2]     else       [price.pricehigh * 0.15]     end   end

It works perfectly for individual functions, but how would a sum the virtual attribute?

Thanks

2

I is possible to do calculations on a virtual attribute... such as sum, or count

I tried using the same as I would on a DB column but of course that doesn't work. ie. Pricelist.sum(:cyberguide)

You're going to have to construct an appropriate sql fragment, eg according to the docs you can do Pricelist.sum("2 * price") - you just need that on steroids.

Fred