Path operators

Given the sequencing pattern to follow a path in FHIRconnect, sometimes it is necessary to access elements back in the path. For this, we introduced the ../ and ^ notations.

The ../ notation is used in openEHR, and its logic is the same as in the command line. It simply goes back one element, accessing the parent.

The same logic is used in FHIR with ^, which was adapted from JSONPath Plus. Both notations can be combined to access parents further back in the hierarchy.

This is usually necessary when elements are contained at different levels.

Examples

- name: "example"
  with:
    fhir: "$resource.somePath"
    openehr: "../data[at0001]/items[at0009]"
# Goes one element back and accesses /data[at0001]/items[at0009]
mappings:
  - name: "example"
    with:
      fhir: "^.code" # Accesses the parent's .code
      openehr: "data[at0001]/items[at0009]"

Recurrence and parent elements

When mapping an Encounter diagnosis into an openEHR problem_diagnosis, we find that the diagnosis type is contained in the Encounter, while the rest of the diagnosis is contained in a referenced Condition.

To maintain the sequencing and faithfully represent recurrence, we need to access the use after slotting the problem_diagnosis.

This requires accessing the parent’s parent (using two ^ notations) to reach diagnosis.use.

- name: "problemDiagnosis"
  with:
    fhir: "$resource.diagnosis"
    openehr: "$archetype"
    type: "NONE"
  followedBy:
    mappings:
      - name: "referencedDiagnose"
        with:
          fhir: "condition.reference"
          openehr: "$reference"
        reference:
          resourceType: "Condition"
          mappings:
            - name: "slot"
              with:
                fhir: "$fhirRoot"
                openehr: "items[openEHR-EHR-EVALUATION.problem_diagnosis.v1]"
              slotArchetype: "EVALUATION.problem_diagnosis.v1"
              followedBy:
                mappings:
                  - name: "diagnosisTyp"
                    with:
                      fhir: "^^.use.coding"
                      openehr: "data[at0001]/items[at0009]"
                    fhirCondition:
                      targetRoot: "^^.use.coding.code"
                      targetAttribute: "value"
                      operator: "one of"
                      criteria:
                        - "referral-diagnosis"
                        - "treatment-diagnosis"

Wrong mapping

Imagine the condition.reference to be 0..n. In this case, the below code would not populate the use.coding.code. Instead, it would make a new empty entry into the problem_diagnose cluster containing only the use code.

This is both a recurrence problem and a structural one, as the use is not contained in the condition.

- name: "problemDiagnosis"
  with:
    fhir: "$resource.diagnosis"
    openehr: "$archetype"
    type: "NONE"
  followedBy:
    mappings:
      - name: "referencedDiagnose"
        with:
          fhir: "condition.reference"
          openehr: "$reference"
        reference:
          resourceType: "Condition"
          mappings:
            - name: "slot"
              with:
                fhir: "$fhirRoot"
                openehr: "items[openEHR-EHR-EVALUATION.problem_diagnosis.v1]"
              slotArchetype: "EVALUATION.problem_diagnosis.v1"

      - name: "diagnosisTyp"
        with:
          fhir: "use.coding.code"
          openehr: "items[openEHR-EHR-EVALUATION.problem_diagnosis.v1]/data[at0001]/items[at0009]"
        fhirCondition:
          targetRoot: "use.coding.code"
          targetAttribute: "value"
          operator: "one of"
          criteria:
            - "referral-diagnosis"
            - "treatment-diagnosis"