Using await in promise chain

Question

I just upgraded to node 8 and want to start working with async/await. I came across an error which took me a while to solve and I was actually just wondering if there's a more graceful way. I didn't want refactor the whole function at this point in time because of all the secondary refactors it would lead to.

async doSomething(stuff) {
...

  return functionThatReturnsPromise()
    .then((a) => ...)
    .then((b) => ...)
    .then((c) => {
      const user = await someService.createUser(stuff, c);
      user.finishSetup();
    });
};

is there a way to be able to use await in the promise chain without having to refactor everything above to be async as well?

Answer 1

The callback is not declared as an async function. You can only await a Promise directly inside of an async function.

async doSomething(stuff) {
// ...

  return functionThatReturnsPromise()
    .then((a) => /* ... */)
    .then((b) => /* ... */)
    .then(async (c) => {
      const user = await someService.createUser(stuff, c);
      return user;
    });
};

Moreover, you shouldn't need to use then if you are leveraging async functions.

async doSomething(stuff) {
// ...

  const a = await functionThatReturnsPromise();
  const b = // ...
  const c = // ...
  const user = await someService.createUser(stuff, c);
  return user;
};