You can add $operations to node-fhir-server-core now. Let's walk through an example of adding /$everything operation to our Patient resource.

First, we will need to define an operation in our config.

const config = { profiles: { patient: { service: path.resolve('./src/patient.js'), versions: [VERSIONS['3_0_1']], operation: [ { name: 'everything', route: '/$everything', method: 'GET', reference: 'https://www.hl7.org/fhir/patient-operation-everything.html' } ] } } }

If we FHIR up our server (GET IT? FHIR UP!?), we should get an error that tells us we have to make a function called everything in our patient.js file. Here is my error.

019-03-08T14:23:43.220Z - error: message=Must include a function for patient with name everything that you specified in your configuration file.

In our patient.js file, just like our other routes, we will add a method for everything.

module.exports.everything = (args, context, logger) => { logger.info(`Running Patient $everything operation`) return new Promise((resolve, reject) => { try { // execute whatever custom operation you want. resolve([]) } catch(err) { reject(err) } }

Restarting your server and navigating your browser to /3_0_1/Patient/$everything, your logger should generate the message above, and your should return an empty array.

Now let's say you want to have a custom operation by Id. Fear not, let's light a fhir under your keyboard and get to work.

Let's add everything-by-id in patient. Go back to your config.

const config = { profiles: { patient: { service: path.resolve('./src/patient.js'), versions: [VERSIONS['3_0_1']], operation: [ { name: 'everything', route: '/$everything', method: 'GET', reference: 'https://www.hl7.org/fhir/patient-operation-everything.html' }, { name: 'everything-by-id', route: '/:id/$everything', method: 'GET', reference: 'https://www.hl7.org/fhir/patient-operation-everything.html' }, ] } } }

If we restart the server we should see an error telling us to make a function called everythingById (notice the camelcase of the name property).

Back in our patient.js

module.exports.everythingById = (args, context, logger) => { logger.info(`Running Patient /:id/$everything`) return new Promise((resolve, reject) => { try { // execute whatever custom operation you want to get patient by id. resolve({resourceType: 'Patient', id: 1}) } catch(err) { reject(err) } }

Navigating in your browser to /3_0_1/Patient/1/$everything should trigger the logger info above and return your patient with ID of 1.

This should give you a start for making custom operations of any kind.