Operations

Adding Custom Operations

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.

Custom Operation by ID

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.