How can i solve this error 'Cannot read properties of undefined (reading 'sign')' on fastify

Question

I am implementing a JWT generator for my backend but when using the fastify way I get this error:

Cannot read properties of undefined (reading 'sign')

so here I am stuck.

Somebody would know the reason for this, I attach fragments of my code.

import fetch from "node-fetch";
import { randomBytes, createHash } from "crypto";
import { PrismaClient, users } from ".prisma/client";
import { Jwt, JwtPayload } from "jsonwebtoken";

import HttpsProxyAgent from "https-proxy-agent";
const proxyAgent = HttpsProxyAgent("http://148.201.1.200:3128");

const fastify = require('fastify')()



function genRandomString(length) {
  return randomBytes(Math.ceil(length)).toString("hex").slice(0, length);
}

function generateJWTToken(user: users) {
  const { password, sal, active, ...enviar } = user;

  const token = fastify.jwt.sign({
    ...enviar,
  });
  

  console.log(token);

  const decoded: Jwt = fastify.jwt.decode(token, { complete: true });

  return {
    token,
    uuid: user.id,
    nombre: `${user.name} ${user.lastname_p} ${user.lastname_m}`,
    exp: (decoded.payload as JwtPayload).exp,
  };
}

main.ts

async function main() {
  app.register(require("@fastify/swagger"), swaggerOptions);
  
  app.register(require('@fastify/jwt'), {
    secret: 'supersecret'
  })

  app.decorate("prisma", prisma);

  app.register(require("@fastify/cors"), {
    origin: "*",
    methods: ["GET", "POST", "PUT", "DELETE", "OPTIONS"],
    allowedHeaders: ["Content-Type", "Authorization", "Accept"],
  });

  app
    .register(authRouterWeb, {
      prefix: "/api/v1/auth-web",
    });

  app.listen(port, (err, address) => {
    if (err) {
      app.log.error(err);
      process.exit(1);
    }
    app.log.info(`server listening on ${address}`);
  });
}

so, please if you have any suggestion or another alternative to change that or improve my code ill be grateful.

score 0 · Answer 1 · answered Jun 30 '22 at 16:23

This error means that fastify.jwt is undefined when this line is executed :

// fastify.jwt === undefined, you cannot access anything from it
const token = fastify.jwt.sign({
  ...enviar,
});

Reading the doc from https://github.com/fastify/fastify-jwt, I assume that you need to create a JWT token, by calling this code :

fastify.register(require('@fastify/jwt'), {
  secret: 'supersecret'
})

You could also find useful informations here : Fastify not defined when trying to sign a jwt with fastify-jwt

How can i solve this error 'Cannot read properties of undefined (reading 'sign')' on fastify

1 Answers1