Can I make this Rails 4 named scope nicer

Question

I believe this is called a named scope, if I am not mistaken. At any rate, does anyone know of a better / more efficient way of coding this..

This is from a Rails 4 Model

 def line_total
   product = Product.find_by_id(self.product_id)
   line_total = self.quantity * product.current_price
   return line_total
 end

What kind of answer are you wishing for? One reading I can recommend is: http://api.rubyonrails.org/classes/ActiveRecord/FinderMethods.html — vee, Sep 19 '13 at 22:57
This isn't a scope, it's just a method. And "more efficient"? You're multiplying two numbers together. Efficiency doesn't enter into it. — user229044, Sep 19 '13 at 23:01

score 1 · Answer 1 · edited Sep 19 '13 at 23:01

1

This isn't appropriate as a scope. A method like you have defined makes the most sense. The method could be simplified though.

Does the model have an association defined to Product? Something like has_one :product? If so, the method could look like this:

class Rails4Model < ActiveRecord::Base

  has_one :product

  def line_total
    quantity * product.current_price
  end

end

edited Sep 19 '13 at 23:01

osahyoun

answered Sep 19 '13 at 22:59

Ross Allen

And, if you are going to call this method on many "Models", you would want to make sure that those fetches use `includes(:product)`, otherwise, a query will be executed every time you call model.line_total. – steakchaser Sep 19 '13 at 23:02

score 1 · Accepted Answer · answered Sep 19 '13 at 23:05

1

 def line_total
   quantity * Product.find(product_id).current_price
 end

answered Sep 19 '13 at 23:05

Ayman

2 Answers2