Filters Within Optional Field Declarations

[jp3477]

I have been able to create a JSON template for a SPARQL endpoint that works pretty well. However, I'm trying to now generate a structure that "conditionally" outputs one of three fields that all share the same root predicate but have different classes for the object. In the below example, the valueQuantity, valueCodeableConcept and valueString fields all originate from the predicate fhir:value.

I attempt to restrict them to different object classes in the $where clause with named variables. However, this does not produce the intended results if the fields are OPTIONAL. While the fields themselves are OPTIONAL, the class declarations in the $where clause seem to be absolute and will run independently of the fields in the translated SPARQL. Is there any way to fix these class declarations within the definition of the fields themselves using this package?

{
    "proto": {
        "id": "?observation$anchor",
        "identifier": {
            "id": "$fhir:identifier$asList$var:identifier",
            "value": "$fhir:value/fhir:v"
        },
        "status": "$fhir:status/fhir:v",
        "code": {
            "id": "$fhir:codeP$var:code$required",
            "coding": {
                "id": "$fhir:coding$asList",
                "system": "$fhir:system/fhir:v",
                "code": "$fhir:codeP/fhir:v",
                "display": "$fhir:display/fhir:v"
            }
        },
        "issued": "$fhir:issued/fhir:v",
        "valueQuantity": {
            "id": "$fhir:value$var:valueQuantity",
            "value": "$fhir:value/fhir:v",
            "code": "$fhir:codeP/fhir:v"
        },
        "valueCodeableConcept": {
            "id": "$fhir:value$var:valueCodeableConcept",
            "coding": {
                "id": "$fhir:coding$asList",
                "system": "$fhir:system/fhir:v",
                "code": "$fhir:codeP/fhir:v",
                "display": "$fhir:display/fhir:v"
            }
        },
        "valueString": "$fhir:value$var:valueString"
    },
    "$prefixes": {
        "fhir": "fhir/mcode.fhir.rdf.ttl/fhir.ttl#"
    },
    "$limit": 20,
    "$limitMode": "query",
    "$where": [
        "?observation a fhir:Observation",
        "?valueQuantity a fhir:Quantity",
        "?valueCodeableConcept a fhir:CodeableConcept",
        "?valueString a fhir:string"
    ]
}

[pasqLisena]

Hi, this is basically a UNION, which we are not supporting.

The only way is is to take note of the class and filter afterwards programmatically (in your JS or other code)

E.g. for valueQuantity, you may have

        "valueQuantity": {
            "id": "$fhir:value$var:valueQuantity",
             "cls": "$rdf:type$var:valueQuantityClass",

And than use the cls value for removing or not the value

[jp3477]

Thanks for the response! That makes sense. I am already using a workaround of that sort, and I think it should be enough.