Transforming a list

When transforming an element that is 0..n, FHIRconnect always appends. If we transform from a 0..n to a 0..1 field, only the last entry of 0..n is mapped.

  - name: "bodySite"
    with:
      fhir: "$resource.bodySite"
      openehr: "$archetype/data[at0012]"

  - name: "bodySiteCluster"
    with:
      fhir: "$resource.bodySite"
      openehr: "$archetype/data[at0001]/items[openEHR-EHR-CLUSTER.anatomical_location.v1]"
    slotArchetype: "CLUSTER.anatomical_location.v1"

In this example, both the cluster and the at0012 (bodySite openEHR) are mapped to bodySite in FHIR. Often, openEHR has additional fields to be more granular, like in this case. FHIR only has the bodySite for that, yet both openEHR fields transform to it. The FHIR bodySite is 0..n, therefore both entries would be appended into the bodySite.

{
  "anatomicalLocation": [
    "left valve"
  ],
  "bodySite": [
    "heart"
  ]
}

{
  "bodySite": [
    "heart",
    "left valve"
  ]
}

N elements to n paths

When mapping a list back from FHIR using the FHIRconnect snippet from above, the problem is that both openEHR paths would be populated.

{
  "bodySite": [
    "heart",
    "left valve"
  ]
}

{
  "anatomicalLocation": [
    "left valve", "heart"
  ],
  "bodySite": [
    "left valve", "heart"
  ]
}

There are different options to tackle this. The template uses only one of them. For example, bodySite in openEHR is 0..0. If both are contained, users can use an extension (see chapter The extension mappings ) to overwrite with the type: NONE and unidirectional, enforcing the mapping to only map into anatomical_location when coming from FHIR to openEHR.