Associated Totals with Eager Loading

I have the following.

@sales = Sale.find(:all, :include => [:sale_items])

I want totals on the sale items. It works if I code it like this.

@sale_item_total = 0
@sales.each do |sale|
@sale_item_total += @sale.sale_items.to_a.sum(&:price)
end
@sale_item_total

The problem is my real world project has nested includes on several
models
and I want totals on all of them so I’m looking for a rails way to
access a
collection of all the associated sale items in an instance variable like
@sale_items without needing to reference each @sale first.

I could pull them out like this but isn’t there a better way?

@sale_items = []
@sales.each do |sale|
sale.sale_items.each do |sale_item|
@sale_items << sale_item
end
end
@sale_item_total = @sale_items.to_a.sum(&:price)

Does Sale.sum(:price, :include => [:sale_items]) do what you want ?

Fred