Treating nil as zero in sum function

Question

I have a Seller model that has_many Items.

I want to get the total sale price of all of a Seller's items.

In seller.rb I have

def total_item_cost 
  items.to_a.sum(&:sale_price)
end

This works fine if all the items have a sale price.
However, if they haven't been sold yet, sale_price is nil and the total_item_cost breaks.

In my app, sale_price can be either a nil or a zero.

In my total_item_cost method, how can I treat nil values as zeros?

Answer 1

items.map(&:sale_price).compact.sum

or

items.map(&:sale_price).sum(&:to_i)

Answer 2

Reject the nil values. items.to_a.reject{|x| x.sales_price.nil?}.sum(&:sale_price)

Answer 3

Assuming sales_price is a column in the DB:

items.sum(:sales_price)