Throw a user-facing error

When running functions in other parts of the platform, such as Workshop or Actions, you may want to throw an error with a detailed message. To do so, throw a UserFacingError from the functions.api module. For example:

Copied!
1from functions.api import function, UserFacingError
2from ontology_sdk import FoundryClient
3from ontology_sdk.ontology.object_sets import AircraftObjectSet
4from ontology_sdk.ontology.objects import Aircraft
5
6
7@function(edits=[Aircraft])
8def edit_exactly_five_aircraft(
9    aircraft_object_set: AircraftObjectSet
10) -> list[OntologyEdit]:
11    aircraft = list(aircraft_object_set)
12    if not len(aircraft) == 5:
13        raise UserFacingError(f"Pass in exactly 5 aircraft. Received ${len(aircraft)}.")
14    ... # edit the objects

When running this as a function-backed Action in a Workshop application with an incorrect number of employees, users will see the following error:

By adding a detailed user facing error message, you can help other users of your function quickly identify and fix the issue.