FHIR Client API Design Ideas

FHIR Client API Design

Following References

A lot of our current code centers around the idea of fetching data about a particular patient. Our FHIR-request wrapping code has encapsulated this nicely already, and as we're looking at using fhir_client, we're realizing it doesn't support most of this.

For example, what if we want to get all observations related to a patient from the past week? Currently, with fhir_client, we might have to do something like this:

patient_response = client.read(FHIR::Patient, fhir_patient_id)
patient = patient_response.resource

observation_response = client.search(FHIR::Observation, search: {
  parameters: {
    patient: patient.id,
    date: ">#{1.week.ago.to_date}"
  }
})
observations = observation_response.resource.entry.map(&:resource)

However, following the pattern of libraries like ActiveRecord, it would be nice to be able to do something like this:

patient = client.find(FHIR::Patient, fhir_patient_id)
observations = patient.observations(date: ">#{1.week.ago.to_date}")

Where the FHIR::Patient instance could remember the client it was fetched from, and could also be aware of associations and use that client to fetch them.

Or -- we could take the ActiveRecord analogy further, and do something like this:

client = FHIR::Client.new(ENV['FHIR_SERVER_URL'])
FHIR::Base.client = client

patient = FHIR::Patient.find(fhir_patient_id)
observations = patient.observations(date: ">#{1.week.ago.to_date}")