I was doing this:
@line_items = LineItems.find_all_by_invoice_id(params[:id])
@payments = Payments.find_all_by_invoice_id(params[:id])
@total = @line_items.sum{ |item| item.cost }
@payment_total = @payments.sum{ |payment| payment.value }
@balance = @total - @payment_total
But when no payments had been made it was coming up with an error when
trying to sum nil, so I did this:
begin
@payment_total = @payments.sum{ |payment| payment.value }
rescue
@payment_total = 0
end
So, when the sum failed it returned @payment_total as zero. Now, SURELY,
there’s a better way to do this? I’m sure it’s obvious when you know
how. Please, enlighten me.
All you need to do to your original code is add a condition to make
sure @payments is not null:
@payment_total = @payments.sum{ |payment| payment.value } unless
@payments.nil?
Or can payment.value be nil for some payments but not others? Inject
could help in that case:
@payment_totals = @payments.inject(0) { |sum, p| sum + p.value unless
p.value.nil? }
Before running either one of these, you can initialize both @total and
@payment_total to zero:
@total, @payment_total = 0, 0
Hope that helps.
PS: Wonder if you need all of these to be @instance_variables ?
On Apr 1, 10:16 am, Tom H. [email protected]
On Wed, Apr 1, 2009 at 9:16 AM, Tom H.
[email protected] wrote:
I was doing this:
@line_items = LineItems.find_all_by_invoice_id(params[:id])
@payments = Payments.find_all_by_invoice_id(params[:id])
@total = @line_items.sum{ |item| item.cost }
@payment_total = @payments.sum{ |payment| payment.value }
You can do
@payment_total = @payments.sum{ |payment| payment.value } if @payments
or
@payment_total = @payments.sum{ |payment| payment.value } rescue 0
or
@payment_total = @payments ? @payments.sum{ |payment| payment.value } :
0
end
So, when the sum failed it returned @payment_total as zero. Now, SURELY,
there’s a better way to do this? I’m sure it’s obvious when you know
how. Please, enlighten me.
–
Greg D.
http://destiney.com/
Thanks Guys, that’s much more Ruby like code!