Firebase Real time database execute conditional queries

Question

I am using Express and Firebase Real time database Admin SDK to manage database. I need to get all the tickets whose status are pending or open from the logged in user, but I am not sure how to get this data and I am not finding the solution in the documentation. In SQL would be something like:

SELECT * 
FROM tickets as t 
INNER JOIN users as u 
WHERE t.owner = u.id
AND (
    status = 'pending' 
    OR status = 'open'
);

In case you need to see some code to understand what I am talking about this is what so far I've tried:

router.post('/', async (req: Request, res: Response) => {
    const existingRef = database.ref('tickets')
        .orderByChild('owner')
        .equalTo(req.user.key)
        .orderByChild('status')
        .equalTo('open')
        .orderByChild('status')
        .equalTo('pending);
    const existingSnapshot = await existingRef.on('child_added');
    if (existingSnapshot.val() !== null) {
        return res.json(existingSnapshot.val());
    }
}

The previous code will return the tickets whose status are pending and open which does not make sense since there should be only one status per ticket.

So, what should I do? Thanks in advance

Answer 1

The Realtime Database can only query on one child field at a time, so the query you're proposing won't work. You'd need to filter the results after fetching them, something like:

const snap = await database.ref('tickets')
  .orderByChild('user').equalTo(user.uid)
  .once('value');

const out = {};
snap.forEach(t => {
  if (['open','pending'].includes(t.child('status').val())) {
    out[t.key] = t.val();
  }
});

res.json(out);

You may want to consider using Cloud Firestore instead, as it can do more complex queries:

firebase.firestore().collection('tickets')
  .where('user','==',user.uid)
  .where('status','in',['open','pending'])