Javascript push object into array not working

Question

im using node mirc to retrieve data from mysql

then i want convert data to array, using code below :

function getQuestion (arr{
    var obj = {};

    connection.connect();
    connection.query("SELECT * FROM quiz", function (err, rows, fields) {
        if (err) throw err;

        for (var i = 0; i < rows.length; i++) {
            var row = rows[i];
            obj = {"id":row.id, "question":row.question, "answers":row.answers.split(", ")};
            f100.push(obj);
        };
    });
    connection.end();
}
f100 = [];
getQuestion();
console.log(f100);

but, its only print []

check if any rows are being retrieved by putting a console.log() statement after the for each statement, to pinpoint where exactly is the problem. — Yahya Uddin
– Yahya Uddin, Commented Sep 6, 2015 at 19:48
@YahyaUddin the data retrieved without problem, im already test — Putra Fajar Hasanuddin
– Putra Fajar Hasanuddin, Commented Sep 6, 2015 at 19:50

thecodeparadox · Accepted Answer · 2015-09-06 19:51:49Z

1

Due to .query()'s async behavior its taking some time to execute, but you're executing the log just after calling the function. You need to put the log withing callback of .query() function.

function getQuestion (arr{
    var obj = {};

    connection.connect();
    connection.query("SELECT * FROM quiz", function (err, rows, fields) {
        if (err) throw err;

        for (var i = 0; i < rows.length; i++) {
            var row = rows[i];
            obj = {"id":row.id, "question":row.question, "answers":row.answers.split(", ")};
            f100.push(obj);
        };

        // do log here
        console.log(f100);
    });
    connection.end();
}
f100 = [];
getQuestion();

answered Sep 6, 2015 at 19:51

thecodeparadox

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Comments

Nick Salloum · Accepted Answer · 2015-09-06 19:51:34Z

1

connection.query is asynchronous, so i'd recommend consoling out f100 inside the connection.query callback. If you want to do something with f100 after it's finished populating, you'd need to pass it into another function from inside the connection query callback. Example:

connection.query("SELECT * FROM quiz", function (err, rows, fields) {
    if (err) throw err;

    for (var i = 0; i < rows.length; i++) {
        var row = rows[i];
        obj = {"id":row.id, "question":row.question, "answers":row.answers.split(", ")};
        f100.push(obj);
    };

    console.log(f100); // should console out correctly here
    handleArray(f100); // passes in f100 to a new function
});

answered Sep 6, 2015 at 19:51

Nick Salloum

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