Canonical ValueSet reference in CodeSystem

[alexmbennett2]

Set the canonical ValueSet in the CodeSystem if it captures the whole codesystem.

To test this:

• Update the a CodeSystem to reference the ValueSet
• SUSHI Check
  • Remove the ValueSet from the IG generation
  • Regenerate the IG without the Valueset
• HAPI Check
  • Delete a ValueSet
  • Post the updated CodeSystem
  • Expand the valueset based on that

[alexmbennett2]

• SUSHI Check
  • Generated the IG fine, just had warnings that the ValueSet is not there
• HAPI Check
  • Failed to expand. May need to add something to the fhir server.
  • Error was: "Invalid request: The FHIR endpoint on this server does not know how to handle GET operation[/ValueSet/$expand] with parameters [[url]]"

[jpwiedekopf]

Hi Alex, I have stumbled onto this issue last week as well, in an unrelated topic. It looks like HAPI FHIR is currently not able to expand the implicit ValueSet URL of indexed CodeSystem resources at all. If you want to try out how it is supposed to work, you could use the public Ontoserver hosted by CSIRO at https://r4.ontoserver.csiro.au/fhir.

I would like to take a stab at this issue, so feel free to assign me here.

[alexmbennett2]

Hi Joshua, glad it wasn't just me hitting that issue. I'll take some time and look at the Ontoserver.

And I'll assign the issue to you, curious to see what you figure out!

[jpwiedekopf]

This might need a bit of work on the upstream. I've opened a issue within hapi-fhir and try to implement what's missing: hapifhir/hapi-fhir#3523.

Edit: However, I'm not quite sure if there is agreement in the FHIR specification crowd on if this is the way the spec intends CodeSystem.valueSet to be handled, and asked in the FHIR chat about this.

[jpwiedekopf]

Alright! First up, it looks like the FHIR bosses agree with this being the way it is meant.

I've also managed to implement the missing functionality for FHIR R4 now, at: https://github.com/jpwiedekopf/hapi-fhir/tree/3523-vs-expand-implicit

Before I can create a PR to the HAPI-FHIR upstream, I'll have to implement the same functionality for DSTU3 and R5 as well, but that should be OK. There isn't actually a lot of version-specific code I had to write, most of the logic is quite version-agnostic.

I'll be off for the next week-and-a-half for some much needed vacation time, so you can expect this being merged to the HAPI FHIR upstream at the end of the month, hopefully ;)

[alexmbennett2]

Sounds good, thanks for escalating this to the big FHIR bosses. This will be useful for more than just us moving forward too. Enjoy your vacation!

[jpwiedekopf]

I've now send a PR to HAPI FHIR, let's see where this leads us ;)