fastify-mongodb : "mongo" is undefined when accessed - node.js

Question

I'm attempting to use Fastify and fastify-monogdb.
Currently I have the following...
In my /src/index.js
const routes = require("./routes");
const fastify = require("fastify")({
logger: true
});
routes.forEach((route, index) => {
fastify.route(route);
});
fastify.register(require("fastify-mongodb"), {
url: "mongodb://localhost:27017/parkedcars"
});
const startFastify = async () => {
try {
await fastify.listen(3333);
fastify.log.info(`server listening on ${fastify.server.address().port}`);
} catch (err) {
fastify.log.error(err);
process.exit(1);
}
};
startFastify();
In my /routes/index.js I have a route...
const carController = require("../controllers/carController");
{
method: "POST",
url: "/api/create/parkedcar",
handler: carController.createParkedCar
}
And finally in my /controllers/carController...
const fastify = require("fastify")();
exports.createParkedCar = async (req, reply) => {
try {
let car = { ...req.body };
const db = fastify.mongo.db
*// will do insert here*
return car;
} catch (err) {
throw boom.boomify(err);
}
};
When I attempt to call:
const db = fastify.mongo.db
I get an error that says...
"Cannot read property 'db' of undefined"
What am I doing wrong here?
How is mongo undefined at this point?
Doesn't "fastify.register" make this accessible to me?

Answer 1

You need to do the require("fastify")() only in your once per application because it is a factory and not a singleton, so every time you run the require you are creating a brand new HTTP server!
The magic is to use the .register in a proper way and/or using function instead of arrow function in the handler.
For your use case you could change the carController:
exports.createParkedCar = function handler (req, reply) {
let car = { ...req.body };
const db = this.mongo.db
*// will do insert here*
db.insert(...)
.then(() => reply.send(car))
.catch((err) => reply.send(boom.boomify(err)))
}
because all the function handlers, in fastify, are bound to the fastify server instance (like this aFunction.bind(fastify)). The arrow functions can't be binded.
Another options is to use the register:
// /routes/index.js
module.exports = (fastify, opts, next) => {
fastify.route({
method: "POST",
url: "/api/create/parkedcar",
handler: async (req, reply) => {
try {
let car = { ...req.body };
const db = fastify.mongo.db
*// will do insert here*
return car;
} catch (err) {
throw boom.boomify(err);
}
});
next() // dont forget it
}
For more info checkout the docs