I just learned Nodejs, now I'm having a problem that I don't know how to add async/await in function service login. I researched today without finding a solution. Please help me. Thank you very much!
userService.js
exports.findUser = async (email, password) => {
var result = null;
User.findOne({
email: email,
password: password,
})
.then((data) => {
if (data) {
result = data;
}
})
.catch((err) => {});
return result;
};
userController.js
exports.login = (req, res, next) => {
var email = req.body.email;
var password = req.body.password;
var data = userService.findUser(email, password);
console.log(data);
if (data !== null) {
res.status(200).json({ message: "null" });
} else {
res.status(401).json({ message: "Incorrect email or password!" });
}
};
Solution
From userService.js it is clear you are using mongoose. to use async and await in nodejs you can edit your code like this...
exports.findUser = async (email, password) => {
try{
var result = await User.findOne({
email: email,
password: password,
})
return result
}catch(e){
// catch errors and do something
}
}
Notice i used try and catch block so that i can catch error if anything goes wrong in the await. after the await resolves you get back a mongodb document same as you will get in the parameter passed to .then in a promise callback function.
The thing with async functions is it allows you to await a promise, basicallly suspending the execution of the function until the promise resolves. So, your code could be rewritten as:
//userService.js
exports.findUser = async (email, password) => {
var result = null;
try{
result = await User.findOne({
email: email,
password: password,
})
} catch(e){
\\handle error
}
return result;
};
//userController.js
exports.login = async (req, res, next) => {
var email = req.body.email;
var password = req.body.password;
var data = await userService.findUser(email, password);
console.log(data);
if (data !== null) {
res.status(200).json({ message: "null" });
} else {
res.status(401).json({ message: "Email hoặc mật khẩu không đúng!" });
}
};
By making both functions async, you can take advantage of the await keyword and promises without the 'callback hell' that appears with .then() and .catch() on promises.
MDN Docs