Inventory accounting: modelling the location of stock items

Question

To keep track of inventory on-hand at different retail branches, we model each individual Stock Item ever purchased and its current location as a field on each entity. This makes it easy to trace faulty stock and where a unit has been inventorised over time.

Problem is, how to model the location of an individual stock item when it can reside in either a Stock Room or some Box in transit that is en route to another location, without muddling the data types of Stock Rooms and Shipments, and potentially other types of locations?

The only solutions our team can think of is to consider that a Shipment is a Location where a stock item can reside, which unfortunately has a source and destination location as well (yuck), or we need to write logic to exclude packaged up stock units when we conduct stock counts, which makes the current location field untrustworthy.

Both solutions seem messy to me. Alternatively, we may need to consider some generic stock accounting design.

Has anyone implemented this kind of stock tracking and is there existing literature about this with accompanying complexities and pitfalls?

Answer 1

I have no experience or literature, but it would seem to me that modeling a Shipment as being on a particular Truck at a given point in time would constitute a meaningful location.

You wouldn't have to track the source or destination location for a Truck entity; a VIN or some other unique ID would do.

I can imagine that a Shipment might change hands several times: first on a Truck, then in a Plane, onto a Train, then another Truck. Perhaps the abstraction is MovingLocation. A unique ID for each would tell you exactly where the Shipment was at a given moment in time.

Each MovingLocation could beacon out there instantaneous lat/lon location as a time series. You don't say if keeping track of that is part of your calculus. I'm spitballing here.