Resolve references on disk

[pieter-edelman-nictiz]

When validating a file on disk using the HL7 Validator, it's not possible to resolve a relative reference. However, sometimes it is required for proper validation to consider the referenced resource. I'm not sure if a "proper" mechanism exists, but it would seem logical to make the Validator treat a relative reference in the form of "ResourceType/id" as a relative reference on disk, so it would search for a file that represents this resource type and id.

Some considerations:

• This behavior could be activated using a switch command line switch.
• There could be rules regarding file names of referenced resources, like naming them according to the id or combination of resource type and id.
• Referenced resources could be required to be in the same folder, or they some command line option could be used to set the folder of referenced resources.

[pieter-edelman-nictiz]

Just opened a draft PR as a demo of a simple approach.

[grahamegrieve]

is this a good feature, is it? How would it work from a user point of view?

[pieter-edelman-nictiz]

Suppose I have a file representing an Observation resource that I want to validate using the Validator. This Observation needs to reference a Patient resource (which also only exists as a file). It would seem logical if in the Observation I could just use:

<subject>
  <reference value="Patient/Everyman01"/>
  <display value="Adam Everyman"/>
</subject>

And that the Validator then would look for a file in the same directory called "Patient-Everyman01.xml" or "Everyman01.xml" and try to read them as the Patient resource. This would align with the way relative references work on a server.

[grahamegrieve]

discussion amongst the committers:

• we won't enable this by default (may have unexpected side effects in existing deployments)
• whatever we do, has to work for validator.fhir.org as well as the CLI validator
• there's lots of patterns that people use. For a survey see line 204 of org.hl7.fhir.igtools.publisher.SimpleFetcher
• so you'd have to provide a pattern, something like a parameter -resolve={type}/{id}.{fmt} which operates from the current directory
• validator.fhir.org would use the same pattern approach inside an uploaded zip file

[pieter-edelman-nictiz]

(link to line 204: https://github.com/HL7/fhir-ig-publisher/blob/be10fd8c5e22415fa5446d4757df905962ea947d/org.hl7.fhir.publisher.core/src/main/java/org/hl7/fhir/igtools/publisher/SimpleFetcher.java#L204)

Seeing the variety of file naming approaches, providing a pattern seems like a good approach. However, maybe there could be simpler alternatives:

• Introduce a flag that behaves similar to -ig in that it scans all json, xml and turtle files in the provided directory and indexes their type and id to resolve references.
• Treat references as (relative or absolute) paths (activated by a command-line flag). The downside is that you cannot just re-use the same files as on a server.

[grahamegrieve]

Committer discussion: we like the first option. @dotasek is going to add a parameter -references that works like the -ig parameter and is used to resolve references

[pieter-edelman-nictiz]

@grahamegrieve @dotasek good to hear, please let me know if I can help out.

[david-simons]

in our set-up we use *.example.xml as file-extension for instances that need to be validated along with the profiles - either in the subfolder tree from our profiling repo or in the NPM package being validated, and hence the scope of the logical IDs.

[david-simons]

again running into this :) we are now forced to fall back to contain <contained> the referenced examples - which may be ok design/test-time for a self-contained test-set, but not practical

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions.

[david-simons]

Committer discussion: we like the first option. @dotasek is going to add a parameter -references that works like the -ig parameter and is used to resolve references

curious if this was implemented?

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 5 days if no further activity occurs. Thank you for your contributions.