Firebase BarcodeScanner get parent/other nodes of a specific child - swift

Question

In my app I have certain items in my firebase database like this:
Categories
Category1
Item1
id: item1
name: Item 1 name
barcode: 473088034839
item2
id: item2
name: Item 2 name
barcode: 564084724885
These items are in a collectionview. I have another view where I'm using a barcodeScanner to scan the barcode of the products in my database. The barcode scanner works great and I'm able to print the barcode of scanned products to the console, and it matches the codes in "barcode" in my database.
The problem is I'm trying to get the name if the item I'm scanning. With the following code I'm able to find/match the barcode I'm scanning with the code in my database:
let someBarcode = Database.database().reference().child("Categories").queryOrdered(byChild: "barcode").queryEqual(toValue: code)
print(someBarcode)
code is the string of numbers I get from scanning a barcode. After finding the correct barcode in my database, how can I then retrieve the current Items id and/or name?

Answer 1

Firebase Realtime Database queries work on a flat list. They can order/filter on a property at a fixed path under each direct child under the location you query on.
So in your scenario you could query across all categories on a fixed property of each category, or you can query a specific category for items with a specific property value. But you can't search across all categories for the ones that contain an item with a certain property value.
The solution is to create an data structure that allows the specific query, typically either by flattening the list you already have, or by adding an additional structure to allow the lookup.
For more on this, see:
Firebase Query Double Nested
Firebase query if child of child contains a value

Answer 2

With Franks help I managed to create a new node in my firebase DB with the barcode codes:
Barcodes
item1 : code1
item2 : code2
item3 : code3
Then I used the following function to
func scanner(_ controller: BarcodeScannerViewController, didCaptureCode code: String, type: String) {
// get product id from Barcodes
Database.database().reference().child("barcodes")
.observeSingleEvent(of: .value) { (snapshot) in
guard let dict = snapshot.value as? [String: Any] else {
self.showNotFoundMessage()
return
}
for (key, value) in dict {
let valueString = "\(value)"
if valueString == code {
self.getProduct(id: key)
return
}
}
self.showNotFoundMessage()
}
}