I'm encountering an issue where I am using a variable within a nested function. After assigning a value to it, I pass it to the parent function. However, when I call the function, nothing is displayed.
function checkUserExists(identifier) {
let user = false;
UsersModel.findOne({ email: identifier }, function (error, foundUser) {
if (!error && foundUser) user = foundUser;
else {
console.log("error or user not found: " + error);
}
});
return user;
}
The issue at hand arises due to the asynchronous nature of the findOne function, causing the user variable to consistently return as false. It is imperative to utilize either async await syntax or incorporate a callback function within the function itself.
Here is an example that utilizes async await:
async function fetchData(key) {
const result = await UsersModel.findOne({ email: key });
if (result.error)
return false;
return result.foundUser;
}
Below is an example that employs a callback function:
function getData(key, callback) {
UsersModel.findOne({ email: key }, (error, user) => {
if (!error) callback();
});
}
Gratitude goes out to FloWy and VLAZ
Prior to this improvement,
function verifyUser(key) {
let user = false;
UsersModel.findOne({ email: key }, function (error, foundUser) {
if (!error && foundUser) user = foundUser;
else {
console.log("error or not found: " + error);
}
});
return user;
}
With the implementation of callback functions within a method,
function verifyUser(key, callback) {
UsersModel.findOne({ email: key }, function (error, foundUser) {
if (!error && foundUser) return callback(foundUser);
else return callback(false);
});
}
When making the call,
verifyUser(username, function (user) {
// user can be utilized here
});
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