Extension methods

An extension always inherits all the mappings contained in the model mapping. It can interact with these existing mappings by starting a mapping method and adding the extends key. Depending on the key different logic is executed.

types Description

add

adds a mapping to the model mapping, always added to the bottom of the file

append

appends mapping logic to a path inside the model mapping

overwrite

overwrites the mapping method with the same name

Add

This extension method adds a mapping method to the model mapping. It is always added at the bottom of the model mapping file. Add methods can also overwrite prior methods to the same path.

Example:

  - name: "problemQualifier"
    extension: "add"
    with:
      fhir: "$resource"
      openehr: "$archetype/data[at0001]/items[openEHR-EHR-CLUSTER.problem_qualifier.v2]"
    slotArchetype: "CLUSTER.problem_qualifier.v2"

This impacts the model mapping file at runtime in the following way:

mappings:

  - name: "contextStartTime"
    with:
      fhir: "$resource.recordedDate"
      openehr: "$composition/context/start_time"
#------ added --------
  - name: "problemQualifier"
    with:
      fhir: "$resource"
      openehr: "$archetype/data[at0001]/items[openEHR-EHR-CLUSTER.problem_qualifier.v2]"
    slotArchetype: "CLUSTER.problem_qualifier.v2"

Append

The append extension method appends a followedBy to a method. The method where it is to be appended to is referenced with the key appendTo. The value used is the name of the mapping method. This can be also the child method. The path then would be appendTo: parent.child

Example of an append extension method:

  - name: "wirkstofftyp"
    extension: "append"
    appendTo: "ingredients"
    followedBy:
      mappings:
        - name: "wirkstofftypExtended"
          with:
            fhir: "$fhirRoot.ingredients.extension.value"
            openehr: "$archetype/items[at0142]"

This would impact a model mapping file at runtime in the following way:

mappings:
  - name: "name"
    with:
      fhir: "$resource.code"
      openehr: "$archetype/items[at0132]"

  - name: "ingredients"
    with:
      fhir: "$resource.ingredient"
      openehr: "$archetype/items[openEHR-EHR-CLUSTER.medication.v2]" # cluster in cluster
    followedBy:
      mappings:
        - name: "ingredient"
          with:
            fhir: "item.as(CodeableConcept)"
            openehr: "items[at0142]"
  #----------- Append -----------------------------------
        - name: "wirkstofftypExtended"
          with:
            fhir: "$fhirRoot.ingredients.extension.value"
            openehr: "$archetype/items[at0142]"

To maintain readability the append is transformed into a followedBy. If more logic needs to be altered, the overwrite method must be used instead.

Overwrite

This method allows to overwrite an existing method contained in the model mapping. The name of the mapping method is the name of the method in the model mapping that will be overwritten.

Example:

  - name: "dateTime"
    extension: "overwrite"
    with:
      fhir: "$resource"
      openehr: "$archetype"
      type: "NONE"
    followedBy:
      mappings:
        - name: "period"
          with:
            fhir: "onset.as(Period)"
            openehr: "$archetype"
            type: "DATETIME"
          followedBy:
            mappings:
              - name: "start"
                with:
                  fhir: "$fhirRoot.start"
                  openehr: "data[at0001]/items[at0077]"
                  type: "DATETIME"

              - name: "lebensphaseCluster"
                with:
                  fhir: "$fhirRoot"
                  openehr: "data[at0001]/items[openEHR-EHR-CLUSTER.lebensphase.v0]"
                slotArchetype: "CLUSTER.lebensphase.v0"

        - name: "dateTime"
          with:
            fhir: "onset.as(DateTime)"
            openehr: "data[at0001]/items[at0077]"

Prior to extension use:

mappings:
  - name: "contextStartTime"
    with:
      fhir: "$resource.recordedDate"
      openehr: "$composition/context/start_time"

  - name: "dateTime"
    with:
      fhir: "$resource.onset"
      openehr: "$archetype/data[at0001]/items[at0077]"

After the extension, the model mapping would look like this at runtime:

mappings:
  - name: "contextStartTime"
    with:
      fhir: "$resource.recordedDate"
      openehr: "$composition/context/start_time"

# ---------- Overwrite ---------------------------
  - name: "dateTime"
    with:
      fhir: "$resource"
      openehr: "$archetype"
      type: "NONE"
    followedBy:
      mappings:
        - name: "period"
          with:
            fhir: "onset.as(Period)"
            openehr: "$archetype"
          followedBy:
            mappings:
              - name: "start"
                with:
                  fhir: "$fhirRoot.start"
                  openehr: "data[at0001]/items[at0077]"

              - name: "lebensphaseCluster"
                with:
                  fhir: "$fhirRoot"
                  openehr: "data[at0001]/items[openEHR-EHR-CLUSTER.lebensphase.v0]"
                slotArchetype: "CLUSTER.lebensphase.v0"

        - name: "dateTime"
          with:
            fhir: "onset.as(DateTime)"
            openehr: "data[at0001]/items[at0077]"