CODEWITHSUNDEEP
javascriptnode.js
Andrew Zaw
Andrew Zaw

Reputation: 814

Converting promise to await/async

Should be a fairly simple and quick question, as I am new to using Promises and await/async

This is my original function with Promises. (I want the res.send and res.redirect to happen after the user is created)

router.post('/add', (req, res) => {
  const user = req.body.user;
  if (user.email && user.username && user.password) {
    User.create(createUserObject(user)).then(
    res.send(user);
    res.redirect('/login'));
  }
});

This is my new function with await/async.

router.post('/add', async (req, res) => {
  const user = req.body.user;
  if (user.email && user.username && user.password) {
    await User.create(createUserObject(user));
    await res.send(user);
    await res.redirect('/login');
  }
});

Is it correct that I need await on every line to make the code function the same? I am concerned that I am using await where I don't need to.

Upvotes: 1

Views: 387

Answers (3)

dooderson
dooderson

Reputation: 565

You don't need to put await in front of every function call, only the ones that are asynchronous and return a promise.

Assuming the line User.create(createUserObject(user)) is the only asynchronous call, that should be the only line that needs an await.

On the other hand, putting await in front of every function call may not harm your code other than making it look more cluttered.

Upvotes: 0

Dai
Dai

Reputation: 155015

Is it correct that I need await on every line to make the code function the same?

No. You can do, but you don't need to.

You only need to use await when a function returns a Promise<T>. If a function returns a "normal" value (a string, number, Object, etc) then the extra await will still work but is not needed.

Upvotes: 0

Kevin.a
Kevin.a

Reputation: 4286

I think this should work

   router.post('/add', async (req, res) => {
      const user = req.body.user;
      if (user.email && user.username && user.password) {
        await User.create(createUserObject(user));
        res.send(user);
        res.redirect('/login');
      }
    });

The only time you're waiting for something is when you wait for the user to be added to the db. So, wherever you wait for something you'll typically get a promise returned. That's where you can use await.

Upvotes: 2

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