Node Functions Return Nothing sqlite3

Question

I'm trying to use sqlite3 in a project and I'm running into a problem. My functions aren't returning any values. I added a console.log before the return statement and oddly enough, it works, but logs after the function has returned.

console.log(getNext());

function establishConnection(callback) {
    const db = new sqlite3.Database('database.db');
    db.serialize(() => {
        callback(db);
    });
    db.close();
}

function getNext() {
    establishConnection(db => {
        db.get('SELECT col1, col2 FROM table ORDER BY priority LIMIT 1;', (err, row) => {
            console.log([row.col1, row.col2]); // works
            return [row.col1, row.col2];       // doesn't work
        });
    });
}

I'm no expert at Node but this seems like something that should work and I don't understand why it doesn't. Could someone please explain this to me and possibly provide a solution?

Andy Gaskell · Accepted Answer · 2018-07-28 17:22:24Z

1

getNext is asynchronous, this is why you see logging after the function "returns". Your code currently uses callback style so this answer will follow your format. Using promises or async/await is a more modern approach.

getNext(result => console.log(result));

function establishConnection(callback) {
    const db = new sqlite3.Database('database.db');
    db.serialize(() => {
        callback(db);
    });
    db.close();
}

function getNext(callback) {
    establishConnection(db => {
        db.get('SELECT col1, col2 FROM table ORDER BY priority LIMIT 1;', (err, row) => {
            callback([row.col1, row.col2]);
        });
    });
}

answered Jul 28, 2018 at 17:22

Andy Gaskell

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