consume

consume( requested : number; initial : number | requested : vector) 🡒 number, process

consume(T.Requested; Initial) returns for every line of T, how much of that request could actually be served given that the initial available quantity was Initial.

For instance, we have a request for 15 elements, and we have 3 available lots of 10 elements each which must be consumed in a specific order (e.g. because of expiration dates). What is the quantity of each lot that is consumed by the request?

We could express such a request in Envision as follows:

Lots.QtyConsumed = consume(Lots.QtyAvailable; qtyRequested) scan Lots.Order

With the amounts defined above, this would return 10 for the first lot, 5 for the second lot, and 0 for the last lot.

It is also possible to use a vector instead of a scalar in the function call:

Lots.QtyConsumed = consume(Lots.QtyAvailable; Items.QtyRequested) by id scan Lots.Order

Note the semicolon ; in the list of arguments

The arguments left of the semicolon are line-level arguments, the arguments right of it are group-level arguments. The arguments will be used for initializing internal process variables - the process does not work directly with the passed arguements themselves, the original sources will never be modified.

Example

table Items[Id] = with
  [|as Id, as Stock|]
  [|"a", 10|]
  [|"b", 7|]


table Orders = with
  [|as OId, as Qty|]
  [|"a", 1|]
  [|"a", 1|]
  [|"a", 2|]
  [|"a", 1|]
  [|"b", 5|]
  [|"b", 10|]
  [|"b", 25|]

expect Orders.Id = Orders.OId

Orders.ServedFromStock = consume(Orders.Qty; Items.Stock) by Id scan Orders.*

show table "Orders" with
  Orders.Id
  Orders.Qty
  Orders.ServedFromStock

This example will produce the following output:

Orders

Note: The consume function will not subtract the consumed quantities from Items.Stock, it will only return the consumed quantities. In the above example, the consumed values returned by the function will be stored in the new table column Orders.ServedFromStock.

See also

• assoc.quantity