Node.JS - Promise to Async/Await example

Question

I currently have a project which makes use of native Promises. I am looking to migrate these Promises over to Async/Await. I am having troubles migrating them over; I am trying to follow this article. Below is the current code with the Promises which need changing to Async/Await.

routes.js

// Importing user information
import user from '../server-controllers/user';

// User Information Route
router.get('/about', (req, res) => {
  user.profile().then((data) => {
    return res.render('user', {
      title: data,
    });
  }).catch((e) => {
    res.status(500, {
      error: e,
    });
  });
});

user.js

/*
This file contains any server side modules needed.
*/

module.exports = {
// Returns information about a user
  profile: () => {
    return new Promise((resolve, reject) => {
      const user = "John Doe";
      resolve(user);
    });
  },
};

If there is any help in what I would need to do to convert these that would be helpful. I don't know if the code needs changing on either the routes or user file (or both).

The error which I am getting in my terminal is [object Error] { ... }

Answer 1

The key thing to remember about async and await is that an async function is really just a function that returns a Promise, and lets you use await to resolve Promises. So when a Promise rejects, if it is awaited then you will get an error thrown in the context of wherever the await is.

So technically, if you want to use async/await syntax, you don't need to change user.js. You could just change routes.js to:

// Importing user information
import user from '../server-controllers/user'

// User Information Route
router.get('/about', async (req, res) => {
  try {
    const data = await user.profile()
    return res.render('user', {
      title: data
    })
  } catch (error) {
    // Runs if user.profile() rejects
    return res.status(500, {error})
  }
})

But user.js is made more succinct when you use an async function:

module.exports = {
  // Returns information about a user
  // This returns a Promise that resolves to 'John Doe'
  profile: async () => 'John Doe'
}