Node JS not updating "global variable" [duplicate] - node.js

Question

This question already has answers here:
How do I return the response from an asynchronous call?
(41 answers)
Closed 5 years ago.
My intended use of the code is to check whether the database have a username and password that is passed to the function in the form of object User.
I initialize the success variable to false. And then I say if I find the record, then I will set it to true. However, the success variable is still false even when the record is found. The variable seems not be updating. Why?
Also, How can I pass back the whole fetcheduser result while I can indicate whether the record is found or not foun? Many thanks
LoginSuccess : function (User) {
var success = false;
function isEmptyObject(obj) {
return !Object.keys(obj).length;
}
function isEmptyObject(obj) {
for (var key in obj) {
if (Object.prototype.hasOwnProperty.call(obj, key)) {
return false;
}
}
return true;
}
var sql = require('mssql');
var config = require('./configuration/sqlconfig');
var fetcheduser;
sql.connect(config).then(function () {
console.log('Connected to DB');
new sql.Request().query("SELECT * FROM dbo.LocalUser WHERE Username = '" + User.username + "' AND Password = '" + User.password + "';")
.then(function (recordset) {
if (isEmptyObject(recordset)) {
console.log("The User does not exist");
} else {
fetcheduser = JSON.parse(JSON.stringify(recordset));
success = true;
console.log("The user is existed.");
}
}).catch(function (err) {
//When errors come
});
});
return success;
}

Answer 1

You'll need to return your Promise in order to get the correct success state. Like so...
function LoginSuccess() {
var success = false;
return sql.connect(config)
.then(() => {
return new sql.Request().query(...).then(
() => success = true,
() => success = false
);
})
.then(() => {
return success;
});
}
LoginSuccess().then(success => ...);

Answer 2

Actually - variable is updating, but way too late - after you returned it. Try to make a result = { success: false } and check the result immediately after return and 5 secs later (or whatever appropriate), and you will see that it has changed: setTimeout(() => console.log(result), 5000)
Anyways, for production, go for the promise solution. Node 7.6 has finally now async/await, so you can get rid of the ugly ...then workarounds.