Rather than passing the fastify instance to every function, how can I pass it at a top level only once so its available to all functions in the controller?
// route file
import { FastifyPluginAsync } from 'fastify'
import RootController from '../root.controller'
const root: FastifyPluginAsync = async (fastify, opts): Promise<void> => {
fastify.get('/', RootController.index(fastify))
fastify.get('/show', RootController.show(fastify))
}
export default root
// controller file
import { FastifyInstance, FastifyRequest, FastifyReply } from 'fastify'
export default {
index: (fastify: FastifyInstance) => async (request: FastifyRequest, reply: FastifyReply) => {
const hugs = fastify.someSupport()
reply.send({ status: 'ok', love: hugs })
},
show: (fastify: FastifyInstance) => async (request: FastifyRequest, reply: FastifyReply) => {
const hugs = 'extra ' + fastify.someSupport()
reply.send({ status: 'ok', love: hugs })
}
}
The answer is a simple, mechanical refactoring using closures:
// controller file
import { FastifyInstance, FastifyRequest, FastifyReply } from 'fastify'
export default async function installRootController(fastify: FastifyInstance, opts): Promise<void> {
fastify.get('/', async (request: FastifyRequest, reply: FastifyReply) => {
const hugs = fastify.someSupport()
reply.send({ status: 'ok', love: hugs })
});
fastify.get('/show', async (request: FastifyRequest, reply: FastifyReply) => {
const hugs = 'extra ' + fastify.someSupport()
reply.send({ status: 'ok', love: hugs })
});
};
The inner functions (the async handlers for / and /show) have access to fastify because it's accessible from lexical scope of the surrounding function. This enables you to encapsulate entire "controllers" as Fastify plugins, ready to install like so:
fastify.register(installRootController);
Note that the "routes" file now has no use.