index.ts

import * as fp from "fastify-plugin";

export default fp(async (server, opts, next) => {
  server.get("/vehicles/:id", {}, async (request, reply) => {
    try {
      const _id = request.params.id;

      const vehicle = await server.db.models.Vehicle.findOne({
        _id
      });

      if (!vehicle) {
        return reply.send(404);
      }

      return reply.code(200).send(vehicle);
    } catch (error) {
      request.log.error(error);
      return reply.send(400);
    }
  });

  server.post("/vehicles", {}, async (request, reply) => {
    try {
      const { Vehicle } = server.db.models;

      const vehicle = await Vehicle.create(request.body);

      return reply.code(201).send(vehicle);
    } catch (error) {
      request.log.error(error);
      return reply.send(500);
    }
  });
  next();
});

refers to https://medium.com/car2godevs/fastify-with-typescript-production-ready-integration-2303318ecd9e