Stream: cql
Topic: Library of FHIRPath?
Paul Lynch (Mar 19 2021 at 21:30):
I am looking at the Library resource and trying to see how one might use it for FHIRPath expressions. Is that an intended use? As I understand, the Library is supposed to define a collection of named things via the Attachments that can be used in Expressions, but I don't a place in the Library resource where a name could be assigned to a FHIRPath expression.
Lloyd McKenzie (Mar 19 2021 at 21:40):
I think there's a tracker item for us to define a syntax
Paul Lynch (Mar 22 2021 at 13:40):
Found it: FHIR-29562. It is "Waiting for Input"-- from whom, it doesn't say. I see @Lloyd McKenzie asked on 2/15, "Where/how are we expecting to use these references?" I think the answer is that we could potentially use them anyplace an Expression is used in a Questionnaire. I have left at comment with that answer.
Paul Lynch (Apr 01 2021 at 19:43):
If one had a series of FHIRPath expressions stored in a Library which depended on each other (like Questionnaire variables can be used be each other or a calculatedExpression-- but am I not thinking of a Questionnaire context here) one would like to be say, "Run the expressions in this library in order and return the result". Is there a way of doing that? I suppose that could just be something an app knows to do with a particular library. Also, note that by "depending on each other" am implying that values from one expression can be feed in as a context variable to a subsequent expression. I am not sure if FHIR-29562 covers that or not.
Bryn Rhodes (Apr 02 2021 at 21:47):
Hi Paul, that gets in to what CQL is already doing (expression dependencies, evaluation order, all that sort of thing). Given that CQL is a superset of FHIRPath, it is possible to define a CQL library of FHIRPath expressions.
Bryn Rhodes (Apr 02 2021 at 21:47):
That would give you dependency tracing and evaluation order.
Last updated: Apr 12 2022 at 19:14 UTC
