Overwriting

Overwrites happen if we write twice in a path that is 0..1. Sometimes this is done, because an e.g. archetype could have two paths for one in FHIR. Here we have to choose which one we prefer. As an example:

mappings: # starts mappings
  - name: "dateTime" # name of the mapping
    with:
      fhir: "$resource.onset" # 0..1
      openehr: "$archetype/data[at0001]/items[at0077]" # 0..1

  - name: "muchCoolerDateTime" # overwrites at0077
    with:
      fhir: "$resource.onset" # 0..1
      openehr: "$archetype/data[at0001]/items[at0078]" # 0..1

Here both elements map the onset. If the at0078 exists in the archetype, we would rather have this one populated, instead of the at0077. Therfore, we write the latter one afterwards. It will overwrite the first one, since it adresses the same path. When mapping back also at0078 will be populated to the onset.

Result:

onset: "12:00"

at0078: "12:00"