Struggling to get data back from mysql using promise-mysql and bluebird

Question

I am trying to use the data from an express request to access a mysql database to use as a response. But am struggling to get the data back using promises.

Express bit

app.get('/loadDrinks', function(req, res) {
    var q = 'SELECT * FROM `Drinks` WHERE `Name` LIKE "%' + req.query.drinks + '%"';
    mysqlQ(q).then(function() {
        console.log(data);
        res.send(" ");
    })
})

The mysql bit I am using promise-mysql and bluebird to handle the promises

function mysqlQ(q) {
    mysql.createConnection({
        host: 'localhost',
        user: 'correctUser',
        password: 'correctPass',
        database: 'correctDB'
    }).then(function(conn) {
        connection = conn;
        var f = connection.query(q);
        //connection.end()
        return f
    }).then(function (rows) {
      return rows;
    })
}

I am getting the error:

TypeError: Cannot read property 'then' of undefined 

on Line 67:14 which is

 mysqlQ(q).then(function() {

But mysqlQ should return the value of Rows

Answer 1

Your endpoint definition lacks the data parameter inside then

app.get('/loadDrinks', function(req, res) {
    var q = 'SELECT * FROM `Drinks` WHERE `Name` LIKE "%' + req.query.drinks + '%"';

    // here you had function() - without data parameter which you try to log further
    mysqlQ(q).then(function(data) {
        console.log(data);
        res.send(" ");
    });
});

And you forgot the return statement in mysqlQ function (your function did not return anything and it was the reason of the TypeError about undefined)

function mysqlQ(q) {
    return mysql.createConnection({
    ...