FHIR Response Utility

Utility for handling the headers, content, and status types for a response

Install

yarn add @asymmetrik/fhir-response-util

Usage

The response utility exposes the following methods which can be used to for different scenarios and different types of responses. They all make certain assumptions about the arguments they receive which are documented below in the arguments section.

This is designed to be used in node-fhir-server-core and similar FHIR servers. There is some pseudocode with each method's description to give an idea of how this might work. If you read the source code for resource controllers in node-fhir-server-core, you can see how we are using this internally.

read

Used when you are returning a Bundle of resources

This will set the correct Content-Type and status code while sending the json back to the client.

const handler = require('@asymmetrik/fhir-response-util');

// Some controller
function getPatientsController(req, res, next) {
  // The user may have some service to fetch results
  service
    .getPatients(req)
    .then((bundle) => {
      // Assuming bundle contains a bunch of patients
      handler.read(req, res, bundle);
    })
    .catch((err) => {
      next(err);
    });
}

readOne

Used when you are returning a single resource of any type.

This will set the correct Content-Type and status code while sending the json back to the client.

const handler = require('@asymmetrik/fhir-response-util');

// Some controller
function getPatientController(req, res, next) {
  // The user may have some service to fetch results
  service
    .getPatient(req)
    .then((patient) => {
      handler.readOne(req, res, patient);
    })
    .catch((err) => {
      next(err);
    });
}

create

Used when you are creating a single resource of any type.

This will set the correct Content-Location, Location, and ETag headers. As well as set the correct status code.

const handler = require('@asymmetrik/fhir-response-util');

// Some controller
function createPatientController(req, res, next) {
  // The user may have some service to fetch results
  service
    .create(req)
    .then((patient) => {
      let json = { id: patient.id, resource_version: patient.meta.versionId };
      let options = { type: 'Patient' };

      handler.create(req, res, json, options);
    })
    .catch((err) => {
      next(err);
    });
}

update

Used when you are updating a single resource of any type

This will set the correct Content-Location, Last-Modified, Location, and ETag headers. As well as set the correct Content-Type and status code.

const handler = require('@asymmetrik/fhir-response-util');

// Some controller
function updatePatientController(req, res, next) {
  // The user may have some service to fetch results
  service
    .update(req)
    .then((patient) => {
      let json = { id: patient.id, resource_version: patient.meta.versionId, created: false };
      let options = { type: 'Patient' };

      handler.update(req, res, json, options);
    })
    .catch((err) => {
      next(err);
    });
}

remove

Used when you are deleting a single resource of any type

This will set the correct ETag header and status code.

const handler = require('@asymmetrik/fhir-response-util');

// Some controller
function removePatientController(req, res, next) {
  // The user may have some service to fetch results
  service
    .remove(req)
    .then((id) => {
      let json = { deleted: id };

      handler.remove(req, res, json);
    })
    .catch((err) => {
      next(err);
    });
}

history

Used when you are querying the history of a resource of any type

This will set the correct Content-Type and status code while sending the json back to the client.

const handler = require('@asymmetrik/fhir-response-util');

// Some controller
function getPatientHistoryController(req, res, next) {
  // The user may have some service to fetch results
  service
    .history(req)
    .then((bundle) => {
      handler.history(req, res, bundle);
    })
    .catch((err) => {
      next(err);
    });
}

Arguments

req and res that you see in each method are from express. res is just a normal response, but request must have a base_version parameter(req.params.base_version). Specifically, it should be one of the valid versions we support in our server, which are '1_0_2', '3_0_1', and '4_0_0'. If you would like us to add more versions for this, just let us know, we use this to determine the correct content-type as well as the url of the resource for the response type and response headers.

read

handler.read(req, res, json);

req

Express request.

Type: Express.req
Required: true

res

Express response.

Type: Express.req
Required: true

json

Bundle FHIR resource.

Type: Object
Required: true

readOne

handler.readOne(req, res, json);

req

Express request.

Type: Express.req
Required: true

res

Express response.

Type: Express.req
Required: true

json

Individual FHIR resource.

Type: Object
Required: true

create

handler.create(req, res, json, options);

req

Express request.

Type: Express.req
Required: true

res

Express response.

Type: Express.req
Required: true

json

Properties from the results. Must have an id

Type: Object
Required: true

json.id

ID of the FHIR resource that was created.

Type: String
Required: true

json.resource_version

If we are using history, which version of the resource did we create.

Type: String
Required: false

options

Additional options needed to set the correct headers in the response.

Type: Object
Required: true

options.type

This helps us set the content-location and location headers. For example, handler.create(req, res, json, { type: 'Patient' }) would allow us to set a header like this, res.set('Location', '4_0_0/Patient/patient-identifier').

Type: 'String'
Required: 'true'

update

handler.update(req, res, json, options);

req

Express request.

Type: Express.req
Required: true

res

Express response.

Type: Express.req
Required: true

json

Properties from the results. Must have an id

Type: Object
Required: true

json.id

ID of the FHIR resource that was created.

Type: String
Required: true

json.resource_version

If we are using history, which version of the resource did we create.

Type: String
Required: false

json.created

Did we create a resource or not. If we created a resource, we need to know so that we can set a res.status of 201, otherwise, we will default to a status of 200.

Type: Boolean
Required: false

options

Additional options needed to set the correct headers in the response.

Type: Object
Required: true

options.type

This helps us set the content-location and location headers. For example, handler.create(req, res, json, { type: 'Patient' }) would allow us to set a header like this, res.set('Location', '4_0_0/Patient/patient-identifier').

Type: 'String'
Required: 'true'

remove

handler.remove(req, res, json);

req

Express request.

Type: Express.req
Required: true

res

Express response.

Type: Express.req
Required: true

json

JSON for the response. Not required but contains the optional deleted property.

Type: Object
Required: false

json.deleted

The deleted property should be the id of the element deleted. For example, handler.remove(req, res, { deleted: 'qwerty-123' }). This allows us to add the identifier as a ETag in the response header.

Type: Object
Required: false

history

handler.history(req, res, json);

req

Express request.

Type: Express.req
Required: true

res

Express response.

Type: Express.req
Required: true

json

Bundle FHIR resource.

Type: Object
Required: true