设置异步等待功能顺序

Question

i have tow functions both are async. i want to make sure one is executed after another the following code is within async

const user= await User.find({
      _id: req.user.id
    });

const userName= `my user name is ${user.userName}`;
const email= `my email is ${user.email}`;

const {response} = await printUser({userName,email};

The problem is the printUser function is executed before im finding the user so the values of userName and email are undefined.

NOTE: the following code is in express router and the find function is working (returing the user)

Answer 1

I'm assuming all of these lines of code are inside an async function as well.

Your problem is that find returns an Array of users and not a single user, change

const user= await User.find({
      _id: req.user.id
    });

To:

const user= await User.findOne({
      _id: req.user.id
    });

If the code is not within a function but in the main file, then yea you're going to have to use callbacks.

Answer 2

You need to use callbacks. Something like below:

User.find({
      _id: req.user.id
    }, function (user) {
    printUser(user.userName, user.email); 
});

Answer 3

Assuming you are mongoose which doesn't return promise for query functions (Read here - https://mongoosejs.com/docs/promises.html#queries-are-not-promises ). You can either use .then or use .exec which will return a proper promise. something like

const user = await (User.find({
      _id: req.user.id
    })).exec();

const userName= `my user name is ${user.userName}`;
const email= `my email is ${user.email}`;

const {response} = await printUser({userName,email};