Nested polymorphic item support

[autark]

I was trying to apply the new polymorphic item support (using v1.0.0) to a resource of type QuestionnaireResponse. While it seems to be possible to query the polymorhpic value[x] nodes located at the root level using just value, nested nodes seems to require one to explicitly write out the value type, eg. valueString.

At root level, answer.value seems to work as expected:

$ node fhirpath -f questionnaireResponse.txt -m stu3 -e "QuestionnaireResponse.item[0].answer.value"
fhirpath(QuestionnaireResponse.item[0].answer.value) =>
[
 "Red"
]

But trying to fetch answers for nested items gives no result:

$ node fhirpath -f questionnaireResponse.txt -m stu3 -e "QuestionnaireResponse.item[0].item[0].answer.value"
fhirpath(QuestionnaireResponse.item[0].item[0].answer.value) =>
[]

$ node fhirpath -f questionnaireResponse.txt -m stu3 -e "QuestionnaireResponse.item[0].answer.item[0].answer.value"
fhirpath(QuestionnaireResponse.item[0].answer.item[0].answer.value) =>
[]

Querying using the specific value type works:

$ node fhirpath -f questionnaireResponse.txt -m stu3 -e "QuestionnaireResponse.item[0].item[0].answer.valueString"
fhirpath(QuestionnaireResponse.item[0].item[0].answer.valueString) =>
[
 "Blue"
]

Also, using some functions seems to throw it off, f.ex. while this works:

$ node fhirpath -f questionnaireResponse.txt -m stu3 -e "QuestionnaireResponse.item.where(linkId='1').answer.value"
fhirpath(QuestionnaireResponse.item.where(linkId='1').answer.value) =>
[
 "Red"
]

a similar query like the following doesn't even though the node is at the root level:

$ node fhirpath -f questionnaireResponse.txt -m stu3 -e "QuestionnaireResponse.descendants().where(linkId='1').answer.value"
fhirpath(QuestionnaireResponse.descendants().where(linkId='1').answer.value) =>
[]

questionnaireResponse.txt

[plynchnlm]

Thanks for the report. I did not consider recursive definitions (item.item and item.answer.item) in my implementation. I will have to find a way to handle that.

I am not sure offhand why the path with "descendants()" is failing, but I will look into that too.

[niquola]

The root of the problem - fhir-fuel/fhir-fuel.github.io#2
We should fix it in FHIR JSON representation!

[plynchnlm]

Fixed in 1.0.1.