Given List A and List B, the filterValues function is an excellent, versatile function for finding the values in List A that exist in List B.
For instance, List A might be the list of product IDs for this order; and list B might be the list of out-of-stock products.
There are lots of use cases for FilterValues.
However, there is also a strong practical need to determine the values in list A that do NOT exist in list B.
I created a custom function to fill this need, and it seems to be fairly well accepted.
But it would be great to see a native, documented, fast FileMaker function that does this job.
You might give it some other name, perhaps others reading this suggestion will come up with good names for the function.
A simple example: List A is the list of products for this order; list B is the list of products previously ordered by this customer.
Which products are being ordered for the first time?
List A might be the list of product IDs for this order; and list B might be the list of Black-Friday-discount products.
Which products in this order will NOT be discounted?
Or - which discounted products did the customer NOT order today, do you want to add one of these products to your order?
List A is the line item list of products that have been pulled for this order, List B is the list of all products for this order.
Which products have not yet been pulled from inventory?
You have shipped the order. The order went out in three boxes. The shipper, or customer, reports that box 1 has been lost, damaged, or delayed.
You know the list of contents of box 1. Which items were NOT in box 1 - and therefore should arrive OK at the customer?