Translator (2.3.0) Unions Same Retrieve With Itself #841
Description
Given the following CQL:
library Example version '1.0.0'
using FHIR version '4.0.1'
valueset "Opioid Pain Medications": 'https://cts.nlm.nih.gov/fhir/ValueSet/2.16.840.1.113762.1.4.1032.34'
define MyRetrieve: [MedicationRequest: "Opioid Pain Medications"]
the CQL-to-ELM Translator 2.3.0 produces the following definition:
{
"name" : "MyRetrieve",
"context" : "Patient",
"accessLevel" : "Public",
"expression" : {
"type" : "Union",
"operand" : [ {
"dataType" : "{http://hl7.org/fhir}MedicationRequest",
"templateId" : "http://hl7.org/fhir/StructureDefinition/MedicationRequest",
"codeProperty" : "medication",
"codeComparator" : "in",
"type" : "Retrieve",
"codes" : {
"name" : "Opioid Pain Medications",
"preserve" : true,
"type" : "ValueSetRef"
}
}, {
"dataType" : "{http://hl7.org/fhir}MedicationRequest",
"templateId" : "http://hl7.org/fhir/StructureDefinition/MedicationRequest",
"codeProperty" : "medication",
"codeComparator" : "in",
"type" : "Retrieve",
"codes" : {
"name" : "Opioid Pain Medications",
"preserve" : true,
"type" : "ValueSetRef"
}
} ]
}
}As you can see, it took the retrieve ([MedicationRequest: "Opioid Pain Medications"]) and unioned it with itself.
If I had to guess, I'd guess that the translator is trying to be smart and union a retrieve using medicationCodeableConcept and another retrieve using medicationReference -- but it's not doing it right.
Although the end result is logically equivalent (since duplicates are removed), it probably isn't great for performance, especially when the retrieves are large.
BTW -- changing the retrieve to [MedicationRequest: medication in "Opioid Pain Medications"] gives the expected definition even though it's basically just an explicit way of saying what the other retrieve said implicitly (since the primaryCodePath is medication):
{
"name" : "MyRetrieve",
"context" : "Patient",
"accessLevel" : "Public",
"expression" : {
"dataType" : "{http://hl7.org/fhir}MedicationRequest",
"templateId" : "http://hl7.org/fhir/StructureDefinition/MedicationRequest",
"codeProperty" : "medication",
"codeComparator" : "in",
"type" : "Retrieve",
"codes" : {
"name" : "Opioid Pain Medications",
"preserve" : true,
"type" : "ValueSetRef"
}
}
}As far as I can tell, this only happens for some resources (like MedicationRequest and MedicationStatement), hence my guess that it has to do with the primaryCodePath pointing to a choice element.