Firebase values are properly pulled but cannot be accessed?

Question

I'm running into a weird issue where once I push a value to a Firebase object, two things happen:

I can't access it in the array I receive when I pull the object from Firebase.
The array I receive has no length property.

Here is what my Firebase structure looks like:

"user_solutions": { "0": { "user_id": 0, "clue_id": 0, "hunt_id": 0, "completed": 1 }, "1": { "user_id": 0, "clue_id": 1, "hunt_id": 0, "completed": 0 }, "2": { "user_id": 0, "clue_id": 1, "hunt_id": 1, "completed": 0 } }, "-KHxBMZwVMzyiMIcbMdr": { clue_id: 1, completed: 0, hunt_id: 0, user_id: 0 }

Here is the problematic function:

userSolutionsRef.orderByChild('user_id').startAt(0).endAt(0).once('value', (snap) => { var solution = snap.val(); for (var i = 0; i < solution.length; i++) { if (solution[i].hunt_id == 0) { solutionsForThisHunt.push(solution[i]); } } this.populateArray(solutionsForThisHunt); });

When I run the debugger, solution has the value Object {0: Object, 1: Object, 2: Object, -KHxBMZwVMzyiMIcbMdr: Object}, but the length property is undefined. solutionsForThisHunt never gets populated. Also, I can access the objects individually in the debugger via snap.val()[0]/snap.val()[1]/snap.val()[2], but for some reason when I try accessing snap.val()[3] it is undefined, although it should be populated.

Does snap.val return a real array or another iterable? What does Array.isArray return? (developer.mozilla.org/de/docs/Web/JavaScript/Reference/…) — Daniel Schmidt
– Daniel Schmidt, Commented May 17, 2016 at 13:36
You are right! I was under the impression it returned an array but it was just an iterable. Your solution worked, thanks. — user3802348
– user3802348, Commented May 17, 2016 at 13:44
Firebase will not return an array here, because it looks like you stored your keys as strings. Storing them as integers would make a difference, although I'd always recommend to not depend on array semantics when it comes to Firebase. — Frank van Puffelen
– Frank van Puffelen, Commented May 18, 2016 at 2:28

Daniel Schmidt · Accepted Answer · 2016-05-17 13:39:27Z

solution seems to be an object with keys, rather than an array. You could do the following

var solution = snap.val(); var array = Object.keys(solution).map(key => ({ ...solution[key], id: key })); for ....

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