Swift Firebase -.queryStarting(atValue:) and .queryEnding(atValue:) returning all children

Question

When I query a specific child I get all the results back instead of the ones specific to what I'm looking for:

For eg if my search text begins with the letter "c" I should only get the cat and the cow from below but for some reason I'm also getting the bull.

root
  |
  @---users
        |
        @---uid_1000
        |    |--uid: "uid_1000"
        |    |--username: "bull"
        |
        @---uid_2000
        |    |--uid: "uid_2000"
        |    |--username: "cat"
        |
        @---uid_3000
             |--uid: "uid_3000"
             |--username: "cow"

I was thinking maybe the issue is because I seem to grab everything at the users node (dictionaries plural) and then loop through the dictionaries that might be the issue but then I realized it should still only be the username values beginning with the letter "c" that should appear inside the dictionaries to begin with and bull should get skipped.

Where am I going wrong at?

let searchText = "c"

let ref = Database.database().reference().child("users")
    .queryOrdered(byChild: "username")
    .queryStarting(atValue: searchText)
    .queryEnding(atValue: searchText + "\u{f8ff}")

ref?.observeSingleEvent(of: .value, with: { (snapshot) in

    if !snapshot.exists() { return }

    // dictionaries plural
    guard let dictionaries = snapshot.value as? [String: Any] else { return }

    dictionaries.forEach({ (key, value) in

        guard let dict = value as? [String: Any] else { return }
        let user = User(dict: dict)

        let isContained = self.users.contains(where: { (containedUser) -> Bool in
            return user.uid == containedUser.uid
        })

        if !isContained {
            self.users.append(user)
            self.collectionView.reloadData()
        }
})

Updated with Json per Frank's request:

{
  "users" : {
    "1000" : {
      "userId" : "1000",
      "username" : "bull"
    },
    "2000" : {
      "userId" : "2000",
      "username" : "cat"
    },
    "3000" : {
      "userId" : "3000",
      "username" : "cow"
    }
  }
}

A picture to match. I excluded the other 2 objects from the json because even though they showed up on my end (I actually got 5 results) I wanted to just focus on what's in the question which is the first 3.

Answer 1

I just tried this code:

let ref = Database.database().reference(withPath: "55574954")
ref.child("users") .queryOrdered(byChild: "username") .queryStarting(atValue: "c") .queryEnding(atValue: "d").observeSingleEvent(of: .value, with: { (snapshot) in
    for child in (snapshot.children.allObjects as! [DataSnapshot]) {
        print(child.key)
    }
})

On this data structure:

{
  "users" : {
    "1000" : {
      "userId" : "1000",
      "username" : "bull"
    },
    "2000" : {
      "userId" : "2000",
      "username" : "cat"
    },
    "3000" : {
      "userId" : "3000",
      "username" : "cow"
    }
  }
}

Live JSON is here.

Running this code prints:

2000

3000

Which is exactly what I'd expect with the data structure above.

Answer 2

I'm not sure why this happened but it was a very odd bug.

1st thing what I didn't add in my question was I had another observer inside the same class as the one I was using for queries.

I had a class property named blockedRef and in viewWillAppear I initialized it with a .observe(.value). This ref has no connection to my users ref, I only was checking there to make sure this user isn’t blocked from whomever. Somehow that blockedRef corrupted my query on the users ref.

Once I removed that blockedRef observer 1 problem was resolved (In my actually project I was initially getting 5 results then after removal I was getting 3 but they were still incorrect).

To fix the problem I removed the instance ref initialization

let ref = Database.database().reference().child("users")....

and instead chained everything needed for the query to the Database object itself and everything worked fine.

Database.database().reference().child("users")
    .queryOrdered(byChild: "username")
    .queryStarting(atValue: searchText)
    .queryEnding(atValue: searchText + "\u{f8ff}")
    .observeSingleEvent(of: .value, with: { ...

The only 2 results that showed up was cat and cow. Very strange bug

let searchText = "c"

Database.database().reference().child("users")
    .queryOrdered(byChild: "username")
    .queryStarting(atValue: searchText)
    .queryEnding(atValue: searchText + "\u{f8ff}")
    .observeSingleEvent(of: .value, with: { (snapshot) in

    if !snapshot.exists() { return }

    // dictionaries plural
    guard let dictionaries = snapshot.value as? [String: Any] else { return }

    dictionaries.forEach({ (key, value) in

        guard let dict = value as? [String: Any] else { return }
        let user = User(dict: dict)

        let isContained = self.users.contains(where: { (containedUser) -> Bool in
            return user.uid == containedUser.uid
        })

        if !isContained {
            self.users.append(user)
            self.collectionView.reloadData()
        }
})