Question

How can this simple new action be refactored?

def new
  @payment = Payment.new(:invoice_id => params[:invoice_id])
  if @payment.invoice.present?    
    @payment.amount = @payment.invoice.balance.abs
  end
  @title = "New payment"
end

It feels a bit clumsy to me.

Thanks for any help!

Answer 1

To simplify your controller, you should move the business logic to your model.

Here’s three suggestion:

If invoice_id will not change over the live of your Payment instance, and you don’t need caching:

  def amount
    invoice.balance.abs
  end

If invoice_id will not change over the live of your Payment instance, but you use the amount value multiple times in your controller/view. (use caching):

  def amount
    @_amount ||= invoice.balance.abs
  end

If invoice_id may change over the live of your Payment instance, and you need caching:

  def amount
    @_amount ||= {}
    @_amount[invoice_id] ||= invoice.balance.abs
  end

end