I’m trying to implement search function for FHIR server and have a question.
The Description & Constraints for SearchParameter.expression says “FHIRPath expression that extracts the values”. (SearchParameter - FHIR v4.0.1)
Is there a method to specify the values using SearchParameter.expression without any external logic??
For example, suppose I want to implement search function for “[base]/AllergyIntolerance?code=xxxx”.
The expression of SearchParameter/clinical-code is “AllergyIntolerance.code | AllergyIntolerance.reaction.substance”, which correspond to CodableConcepts, and the type of the SearchParameter is “token”.
As explained in SearchParameter - FHIR v4.0.1, CodeableConcepts may contain text and/or multiple codings, where the codings themselves contain a code and a system.
I suppose “[base]/AllergyIntolerance?code=xxxx” should search for codes and not for systems. Code elements and system elements, however, are both children of Coding elements and look parallel. Is there any definition or description which element is representing the “value” for the parent Coding element?