map().sum could be sum(xx)

[lelelelemon]

ror_ecommerce/app/./models/cart.rb:107:    shopping_cart_items.map(&:total).sum
ror_ecommerce/app/./models/cart.rb:115:    shopping_cart_items.map(&:quantity).sum

to

shopping_cart_items.sum(:total)
shopping_cart_items.sum(:total)

doing sum is faster in db side

[drhenner]

hmmm. I guess my answer is "it depends". If shopping_cart_items are loaded it's best to just do the math in ruby.

   shopping_cart_items.loaded? ? shopping_cart_items.map(&:total).sum : shopping_cart_items.sum(:total)

Also I assume most times this method is used, shopping_cart_items will eventually be loaded. So maybe ruby math would be better. Plus if you need to run shopping_cart_items.sum(:total) & shopping_cart_items.sum(:quantity) you now have two queries then a possible 3rd query later if shopping_cart_item objects are needed.

I think optimizing this will eventually be up to the implementation. The frontend of ror_ecommerce will be updated by most sites and hence I'm leaning toward keeping the method as it currently stands and let any dev optimize for their site.

That said, this is interesting and I'd like to here your thoughts on my reasoning.