Sum of all values for field in table

How can I get a sum of all values of 1 field of a table. Eg. I’m creating an order and want to show the current total value of the order on the screen.

As far as I can see I can only show the values for:

Selected Row: SUM(elements.Order[“0”].selected_item.price)
Checked Rows: SUM(elements.Order[“0”].checked_items.price)

Is there an equivalent for elements.Order[“0”].all_items and if not how can I obtain this info?

Thanks

That’s not possible at this moment. SUM() works with Arrays fields only.