Stream: implementers
Topic: Incorrect Constraints for valid resources
Sasa (Oct 17 2018 at 16:25):
I posted earlier about constraints: https://chat.fhir.org/#narrow/stream/4-implementers/subject/constraints.20questions/near/198712
I'd really appreciate some help to try and figure out these constraints. Basically to sum it I believe some constraints to be incorrect i.e. not evaluate to true.
e.g.
vitalsigns profile constraint vs-2 - (component.empty() and related.empty()) implies (dataAbsentReason or value)
or
obs-7 - (value.empty() or code!=component.code)
in both cases it's possible to have valid observations that don't meet the constraints, because of undefined behavior. I.e the expressions don't evaluate to true.
e.g. it's possible to have the case for vs-2 where the constraint is
(true) implies ({} or { someValue })
that means you get
{} or { someValue}, which isn't defined in the FHIRPath spec.
Eric Haas (Oct 17 2018 at 16:40):
this is a known issue and corrected in FHIR Version4, however we won't be making a change in STU3. Some servers have turned it off or corrected there implementations.
Last updated: Apr 12 2022 at 19:14 UTC
