Fetch all uid from firebase database using swift code - swift

Question

I have this database (see the link above with the image) and a code with a path, that leads to the destination using:
databaseReference.child("users").child(currentUser!.uid).child("todo-list")
Under the first node "users", the next level is a keyvalue for userID, and later there are more sub-levels "todo-list" etc.
I would like to fetch the data from all uid available. How can I make the query?
Here is the code:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
databaseReference = Database.database().reference()
currentUser = Auth.auth().currentUser
let todoListRef = databaseReference.child("users").child(currentUser!.uid).child("todo-list")
todoListRef.observe(DataEventType.value, with: { (DataSnapshot) in
self.itemsToLoad.removeAll()
let enumerator = DataSnapshot.children
while let todoItem = enumerator.nextObject() as? DataSnapshot
{
let item = todoItem.value as AnyObject
self.itemsToLoad.append(item)
}
self.itemsToLoad = self.itemsToLoad.reversed()
self.tableView.reloadData()
})
}

Answer 1

It's quite similar to the code you already have. Instead of observing /users/$uid, you observe the entire /users node. And then you add an extra loop in the closure, to iterate over all the users.
So:
let usersRef = databaseReference.child("users")
usersRef.observe(DataEventType.value, with: { (usersSnapshot) in
let userEnumerator = usersSnapshot.children
while let user = userEnumerator.nextObject() as? DataSnapshot {
let uid = user.key
let todoEnumerator = user.childSnapshot(forPath: "todo-list").children
while let todoItem = todoEnumerator.nextObject() as? DataSnapshot {
let item = todoItem.value as AnyObject
self.itemsToLoad.append(item)
}
}
})
The added while loops over the users, while the inner while loops over the todo's for each user. I removed the code related to the table view, since what you want to do there doesn't depend on Firebase.