Stream: fhirpath
Topic: Polymorphic roots in FHIRPath
Ewout Kramer (May 25 2018 at 14:49):
The SearchParameters currently use Resource.meta.lastUpdated as a FHIRPath path to express a search parameter used on all resources. This seems to make sense, but I had not implemented this kind of polymorphism in FHIRPath, and we have not documented this in the spec either. The .NET FHIRPath engine has now been updated to support this construct, but I'd like to get confirmation that this use is intentional - as the same result could be obtained by just doing just meta.lastUpdated, since that would work on any resource as well.
Steve Munini (May 25 2018 at 15:42):
We implemented the polymorphic behavior for SearchParameters and it appears to work well. I would be in favor of keeping it as is over using an abbreviated expression like meta.lastUpdated. It provides some consistency in the spec to require the Resource name first in my opinion for SearchParameters.
Grahame Grieve (May 25 2018 at 19:14):
it's intentional on my part at least
Ewout Kramer (May 29 2018 at 09:06):
So, we need to add this to the FHIR-specific appendix to the FHIRPath spec. Alas, I cannot locate that section anymore, where did it go?
Grahame Grieve (May 29 2018 at 12:56):
it moved into the fhir spec itself
Grahame Grieve (May 29 2018 at 12:56):
http://build.fhir.org/fhirpath.html
Ewout Kramer (May 30 2018 at 07:12):
it moved into the fhir spec itself
Ah, I think I knew, but was not able to locate it. I had actually looked under Foundation (http://build.fhir.org/foundation-module.html) but could not find it there. Since the FHIRPath spec has a description of how to navigate v2, shouldn't we have a link to the FHIR/CQL appendices from there too?
Anyway, I'll create a GF to describe the polymorphic behaviour of path roots in FHIR.
Ewout Kramer (May 30 2018 at 07:18):
Last updated: Apr 12 2022 at 19:14 UTC
