CODEWITHSUNDEEP
ruby-on-railsrubyactiverecord
gcstr
gcstr

Reputation: 1527

ActiveRecord sum

I have a model which contains items for sale. The model is mirroring an API, so I can't change it's structure.

In this model I have the fields price and sold_quantity.

It doesn't seem right to iterate through the query with a loop. 

current_user.items.each do |item|
  total += item.price * item.sold_quantity
end

Is there a way to get the same total using only ActiveRecord? Like .sum(:price) but multiplying by sold_quantity?

Upvotes: 1

Views: 860

Answers (3)

Brent Eicher
Brent Eicher

Reputation: 1050

One way you could approach this would be to move this logic into the Item class:

class Item < ActiveRecord::Base
  ...

  def total
    self.price * self.sold_quantity
  end

  def self.sold_value
    all.map{|a| a.total}.sum
  end
end

Here each instance of item is calculating it's own total, and a class method allows you get the sold value on any collection of items.

@user.items.sold_value

Upvotes: 1

akbarbin
akbarbin

Reputation: 5105

You can do this:

current_user.items.sum { |item| item.price * item.sold_quantity }

I hope this help you.

For more information sum in AR

Upvotes: 1

Jordan Running
Jordan Running

Reputation: 106027

You probably want this:

current_user.items
  .select('items.*, items.price * items.sold AS total')
  .all

Or, if you want the totals and nothing else:

current_user.items.pluck('items.price * items.sold')

Upvotes: 3

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