Firebase looping multi level nodes - ios

Question

I am trying to get results from a node that has one more level of nodes and cannot get through it:
I am retrieving the data like this (it works perfectly but not for the node called "items"):
func fetchMeals() {
print("start pulling data")
let user = Auth.auth().currentUser?.uid
ref.child("Users_Food_Data").child(user!).queryOrderedByKey().observeSingleEvent(of: .value, with: { snapshot in
if snapshot.value as? [String : AnyObject] != nil {
let allMeals = snapshot.value as! [String : AnyObject]
self.foodArray.removeAll()
for (_, value) in allMeals {
let foodToShow = FoodStruct()
if let calories = value["calories"] as? String,
let itemCarbs = value["energy"] as? String,
let itemProteins = value["proteins"] as? String,
let itemFat = value["fat"] as? String,
let date = value["date"] as? String,
let id = value["id"] as? String,
let name = value["name"] as? String,
let interval = value["interval"] as? Int {
foodToShow.itemKcal = calories
foodToShow.itemCarbs = itemCarbs
foodToShow.itemProteins = itemProteins
foodToShow.itemFat = itemFat
foodToShow.id = id
foodToShow.interval = interval
foodToShow.date = date
foodToShow.itemName = name
self.foodArray.append(foodToShow)
self.collectionView?.reloadData()
}
self.breakfastArray.sort(by: {$0.interval! > $1.interval!})
}
}
})
}
And the database looks like this:
"Users_Food_Data" : {
"JztkBihGgda0jtSpe6pNwt8hZu13" : {
"Breakfast:23 Sep 2017" : {
"calories" : "1145.0",
"date" : "23 Sep 2017",
"energy" : "238.8",
"fat" : "3.0",
"id" : "-Kukx_9lSpCh3lcEMzap",
"interval" : 1.506207565807117E9,
"items" : {
"-KukxKAntXDaS__v3ZLA" : {
"calories" : "30",
"date" : "23 Sep 2017",
"energy" : "6",
"fat" : "0.1",
"interval" : 1.506207500336909E9,
"itemKey" : "-KukxKAntXDaS__v3ZLA",
"mealKey" : "-KukxKAntXDaS__v3ZLB",
"name" : "Strawberries",
"proteins" : "0.8",
"quantity" : "3"
},
"-KukxLYmyg32lU1D3Wh3" : {
"calories" : "29",
"date" : "23 Sep 2017",
"energy" : "9",
"fat" : "0.5",
"interval" : 1.506207505968336E9,
"itemKey" : "-KukxLYmyg32lU1D3Wh3",
"mealKey" : "-KukxLYmyg32lU1D3Wh4",
"name" : "Lemon",
"proteins" : "1.1",
"quantity" : "1"
}
},
"name" : "Breakfast",
"proteins" : "17.0"
},
"Breakfast:24 Sep 2017" : {
"calories" : "959.0",
"date" : "24 Sep 2017",
"energy" : "106.4",
"fat" : "46.1",
"id" : "-KunWOZeSxW9eCIA6O1z",
"interval" : 1.506250519537633E9,
"items" : {
"-KulrJq6jOpsG6oiJuDM" : {
"calories" : "458",
"date" : "24 Sep 2017",
"energy" : "4.6",
"fat" : "45",
"interval" : 1.506222704055992E9,
"itemKey" : "-KulrJq6jOpsG6oiJuDM",
"mealKey" : "-KulrJq6jOpsG6oiJuDN",
"name" : "Coconut",
"proteins" : "4",
"quantity" : "1"
},
How do I do that when I know only "Users_Food_Data" and user ID. I just want to list them in the apropiate cells.

Answer 1

Here is my suggestion.
First looking on your database structure, you currently have something like this :
Users_Food_Data
|_userid
|_FoodStruct
|_items
|_id_1
|_data like calories, date...
|_id_2
|_data...
There is too much nodes and this kind of hierarchy doesn't respect what we call Denormalization. Remember that Firebase database is like a NoSQL database and it's a big difference compared to SQL classic databases. Here is an explanation to the best practice to denormalize your database structure : Structure your database
What i can suggest is structure your database more like this :
One node :
UsersFood
|_userid
|_breakfeast_id_1
|_breakfeast_id_2...
2nd node
Breakfeasts
|_breakfeast_id_1
|_item_id_1
|_item_id_2...
3rd node
Items
|_item_id_1
|_calories
|_date
|_energy...
Then in your code, you can :
Observe with a single event on UsersFood node all the breakfeast ids
Then with all breakfeast ids get items_id
Finally get items_id data
Hope it will help you through your code.
Edit 1 : You can also loop through a child node by using this :
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
//DO WHAT YOU NEED TO DO
}