CODEWITHSUNDEEP
javascriptnode.jsmongodb
User
User

Reputation: 403

Promise.all with dependency of first promise response on second promise

I am trying to use Promise.all of which, second promise is dependent on first promise response. Here is my code

let user = await userService.getByKey({ _id: params.userId });
let room = await matchService.findUserInRoom(user._id);
let match = await matchService.findMatch(params.userId);

But what now I was trying is to do it using Promise.all. Something like

let [user, room, match ] = await Promise.all([firstPromise, secondPromise, thirdPromise])

And I just don't know how to do it this way, tried a lot to find some reference but unable to. As because my second promise is dependent on the response of first promise just stuck how to pass this way

Upvotes: 0

Views: 1273

Answers (1)

polyglot
polyglot

Reputation: 862

You can't call the first and second asynchronous API calls concurrently, but third one is independent so you can do it like the following:

async function getRoom(params) {
   const user = await userService.getByKey({ _id: params.userId });
   const room = await matchService.findUserInRoom(user._id);
   return [user, room];
}

const [[user, room], match] =  await Promise.all([
   getRoom(params),
   matchService.findMatch(params.userId)
]);

Upvotes: 3

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