FHIR Chat · extension-regex usage · implementers

Stream: implementers

Topic: extension-regex usage

view this post on Zulip Reece Adamson (Jul 05 2019 at 03:24):

Looking at the StructureDefinitions in profiles-types.json from the master set of FHIR definitions I noticed that the extension-regex for Extension.url is on the ElementDefinition.type.code, whereas the other StructureDefinitions with a regex have it on the ElementDefinition.type.

For reference the Extension.url regex extension looks like this:

{
              "id": "Extension.url",
              "path": "Extension.url",
              "representation": [
                "xmlAttr"
              ],
              "comment": "The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.",
              "min": 1,
              "max": "1",
              "base": {
                "path": "Extension.url",
                "min": 1,
                "max": "1"
              },
              "type": [
                {
                  "_code": {
                    "extension": [
                      {
                        "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-json-type",
                        "valueString": "string"
                      },
                      {
                        "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-xml-type",
                        "valueString": "xsd:string"
                      },
                      {
                        "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-rdf-type",
                        "valueString": "xsd:string"
                      },
                      {
                        "url": "http://hl7.org/fhir/StructureDefinition/regex",
                        "valueString": "((http|https)://([A-Za-z0-9\\\\\\.\\:\\%\\$]*\\/)*)?(Account|ActivityDefinition|AdverseEvent|AllergyIntolerance|Appointment|AppointmentResponse|AuditEvent|Basic|Binary|BiologicallyDerivedProduct|BodyStructure|Bundle|CapabilityStatement|CarePlan|CareTeam|CatalogEntry|ChargeItem|ChargeItemDefinition|Claim|ClaimResponse|ClinicalImpression|CodeSystem|Communication|CommunicationRequest|CompartmentDefinition|Composition|ConceptMap|Condition|Consent|Contract|Coverage|CoverageEligibilityRequest|CoverageEligibilityResponse|DetectedIssue|Device|DeviceDefinition|DeviceMetric|DeviceRequest|DeviceUseStatement|DiagnosticReport|DocumentManifest|DocumentReference|EffectEvidenceSynthesis|Encounter|Endpoint|EnrollmentRequest|EnrollmentResponse|EpisodeOfCare|EventDefinition|Evidence|EvidenceVariable|ExampleScenario|ExplanationOfBenefit|FamilyMemberHistory|Flag|Goal|GraphDefinition|Group|GuidanceResponse|HealthcareService|ImagingStudy|Immunization|ImmunizationEvaluation|ImmunizationRecommendation|ImplementationGuide|InsurancePlan|Invoice|Library|Linkage|List|Location|Measure|MeasureReport|Media|Medication|MedicationAdministration|MedicationDispense|MedicationKnowledge|MedicationRequest|MedicationStatement|MedicinalProduct|MedicinalProductAuthorization|MedicinalProductContraindication|MedicinalProductIndication|MedicinalProductIngredient|MedicinalProductInteraction|MedicinalProductManufactured|MedicinalProductPackaged|MedicinalProductPharmaceutical|MedicinalProductUndesirableEffect|MessageDefinition|MessageHeader|MolecularSequence|NamingSystem|NutritionOrder|Observation|ObservationDefinition|OperationDefinition|OperationOutcome|Organization|OrganizationAffiliation|Patient|PaymentNotice|PaymentReconciliation|Person|PlanDefinition|Practitioner|PractitionerRole|Procedure|Provenance|Questionnaire|QuestionnaireResponse|RelatedPerson|RequestGroup|ResearchDefinition|ResearchElementDefinition|ResearchStudy|ResearchSubject|RiskAssessment|RiskEvidenceSynthesis|Schedule|SearchParameter|ServiceRequest|Slot|Specimen|SpecimenDefinition|StructureDefinition|StructureMap|Subscription|Substance|SubstanceNucleicAcid|SubstancePolymer|SubstanceProtein|SubstanceReferenceInformation|SubstanceSourceMaterial|SubstanceSpecification|SupplyDelivery|SupplyRequest|Task|TerminologyCapabilities|TestReport|TestScript|ValueSet|VerificationResult|VisionPrescription)\\/[A-Za-z0-9\\-\\.]{1,64}(\\/_history\\/[A-Za-z0-9\\-\\.]{1,64})?"
                      }
                    ]
                  }
                }
              ],
              "isModifier": false,
              "isSummary": false
            }

whereas the other FHIR datatypes, like uri, have it on the type element:

{
              "id": "uri.value",
              "path": "uri.value",
              "representation": [
                "xmlAttr"
              ],
              "min": 0,
              "max": "1",
              "base": {
                "path": "uri.value",
                "min": 0,
                "max": "1"
              },
              "type": [
                {
                  "extension": [
                    {
                      "url": "http://hl7.org/fhir/StructureDefinition/regex",
                      "valueString": "\\S*"
                    }
                  ],
                  "_code": {
                    "extension": [
                      {
                        "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-json-type",
                        "valueString": "string"
                      },
                      {
                        "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-xml-type",
                        "valueString": "xsd:anyURI"
                      },
                      {
                        "url": "http://hl7.org/fhir/StructureDefinition/structuredefinition-rdf-type",
                        "valueString": "xsd:string"
                      }
                    ]
                  }
                }
              ],
              "isModifier": false,
              "isSummary": false
            }

based on the context from the regex-extension StructureDefinition I was expecting it to be on the ElementDefinition. I can see that it might be undesirable to have it on the ElementDefinition because of elements that have a choice of type.

"context": [
          {
            "type": "element",
            "expression": "Questionnaire.item"
          },
          {
            "type": "element",
            "expression": "ElementDefinition"
          }
        ]

Is there a reason for putting the regex-extension in one place or the other and should they be treated differently depending on if its on the type or the type.code?

view this post on Zulip Grahame Grieve (Jul 05 2019 at 09:26):

should be consistent. But I'm not sure where it should be

view this post on Zulip Lloyd McKenzie (Jul 05 2019 at 14:10):

It should be on ElementDefinition. We're qualifying the whole definition and that's where we put other constraints like maxLength.

view this post on Zulip Reece Adamson (Jul 08 2019 at 14:13):

Thanks! Should I submit a tracker ticket for this? I'd be happy to help implement a fix if desired.

view this post on Zulip Lloyd McKenzie (Jul 08 2019 at 16:20):

Please. And a pull request is always welcome

Last updated: Apr 12 2022 at 19:14 UTC


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