Firebase array-contains - search through the values not the keys

Question

How do you query for a value in an array that has a numeric keyset?

For example this query does not work because I believe it is looking at the indexing rather then the values:

var db = firebase.firestore();
var users = db.collection("Users");
var currentUser = firebase.auth().currentUser;
var result = users.where('liked', 'array-contains', currentUser.uid);
if (result.length > 0) {
  return 'You have a match!';
} else {
  return 'No matches';
}

Answer 1

As Stratubas commented, the problem is in this code:

var result = users.where('liked', 'array-contains', currentUser.uid);

This code constructs a query, but does not yet execute the query. So result is a Query object. To execute the query, and get the results from the server, you call get() on the query, which then returns a Promise<QuerySnapshot>. Once the promise results, you can handle the results in the QuerySnapshot object.

var query = users.where('liked', 'array-contains', currentUser.uid);
query.get().then(function(querySnapshot) {
  if (querySnapshot.size > 0) {
    console.log('You have a match!');
  } else {
    console.log('No matches');
  }
});

In more modern JavaScript, the above can also be written as:

let query = users.where('liked', 'array-contains', currentUser.uid);
let querySnapshot = await query.get()
if (querySnapshot.size > 0) {
  console.log('You have a match!');
} else {
  console.log('No matches');
}