How do I loop all Firebase children at once in the same loop?

Question

I have three nodes in firebase that I would like to loop through using the same loop. I'm successfully able to loop through a single node (cookies) using this code:

databaseRef.child("cookies").observeSingleEvent(of: .value, with: {(snapshot) in for item in snapshot.children.allObjects as! [DataSnapshot] { let thisItem = item.value as! NSDictionary if(favoriteArray.contains(item.key)) { self.numberOfRecipes.append(thisItem["recipeHeaderFirebase"] as! String) let tempRecipe = Recipe() tempRecipe.fbKey = item.key tempRecipe.recipeHeaderObject = (thisItem["recipeHeaderFirebase"] as! String) tempRecipe.recipeTextObject = (thisItem["recipeIngredientsTextFirebase"] as! String) tempRecipe.recipeImageObject = (thisItem["recipeImageFirebase"] as! String) self.recipeClassArray.append(tempRecipe) } } })

I would now like to loop the two remaining nodes as well. Any Ideas?

I tried adding additional nodes, but a print in the console shows that it only adds from the last node. See code below:

 self.databaseRef.child("cookies").observeSingleEvent(of: .value, with: {(snapshot) in self.databaseRef.child("dessert").observeSingleEvent(of: .value, with: {(snapshot) in self.databaseRef.child("breakfast").observeSingleEvent(of: .value, with: {(snapshot) in for item in snapshot.children.allObjects as! [DataSnapshot] { let thisItem = item.value as! NSDictionary if(favoriteArray.contains(item.key)) { self.numberOfRecipes.append(thisItem["recipeHeaderFirebase"] as! String) let tempRecipe = Recipe() tempRecipe.fbKey = item.key tempRecipe.recipeHeaderObject = (thisItem["recipeHeaderFirebase"] as! String) tempRecipe.recipeTextObject = (thisItem["recipeIngredientsTextFirebase"] as! String) tempRecipe.recipeImageObject = (thisItem["recipeImageFirebase"] as! String) self.recipeClassArray.append(tempRecipe) } } print(self.numberOfRecipes.count) print(self.recipeClassArray) let url = URL(string: self.recipeClassArray[self.currentView].recipeImageObject) self.recipeImageUI.kf.setImage(with: url) //SÄTTER IN BILD MED KINGFISHER self.recipeHeader.text = self.recipeClassArray[self.currentView].recipeHeaderObject //SÄTTER IN HEADER self.ingredientText.text = self.recipeClassArray[self.currentView].recipeTextObject //SÄTTER IN TEXTEN self.animateFunc(image: self.recipeImageUI, labelHeader: self.recipeHeader, labelText: self.ingredientText) //FUNKTION FÖR ATT ANIMERA }) }) })

You can embed the observes into each other. For example, something like that: databaseRef.child("cookies").observeSingleEvent(of: .value, with: {(snapshot) in databaseRef.child("secondNode").observeSingleEvent(of: .value, with: {(snapshot) in ... and so on. This is technically not one loop but the data access happening one after another — user6338195
– user6338195, Commented Oct 12, 2017 at 21:36
Thanks, but I did a print in the console and it only seems to add from the last node, ignoring the first two listed... Updating my post above :) Can you see what's missing? — Joakim Sjöstedt
– Joakim Sjöstedt, Commented Oct 12, 2017 at 21:59
Yes, because the print only called at the deepest level... so try something like that: self.databaseRef.child("cookies").observeSingleEvent(of: .value, with: {(cookiesSnapshot) in print("cookies: (cookiesSnapshot)") self.databaseRef.child("dessert").observeSingleEvent(of: .value, with: {(dessertSnapshot) in print("dessert: (dessertSnapshot)") self.databaseRef.child("breakfast").observeSingleEvent(of: .value, with: {(breakfastSnapshot) in print("breakfast: (breakfastSnapshot)") — user6338195
– user6338195, Commented Oct 12, 2017 at 22:31

Vitalii · Accepted Answer · 2017-10-13 00:21:17Z

You can convert snapshot to dict and loop through the dict:

databaseRef.child("cookies").observeSingleEvent(of: .value, with: { snapshot in if let dict = snapshot.value as? Dictionary<String, Dictionary<String, Any>> { for (key, value) in dict { if let recipeHeader = value["recipeHeaderFirebase"] as? String, favoriteArray.contains(key) { self.numberOfRecipes.append(recipeHeader) ... } } } }

or you can use the enumerator:

databaseRef.child("cookies").observeSingleEvent(of: .value, with: { snapshot in let enumerator = snapshot.children while let (key, value) = enumerator.nextObject() as? FIRDataSnapshot { if let recipeHeader = value["recipeHeaderFirebase"] as? String, favoriteArray.contains(key) { self.numberOfRecipes.append(recipeHeader) ... } } }

Thanks for all the quick replies! I'll try them out and get back when I've tried them out! :)

score 1 · Accepted Answer · 2019-07-31 06:56:34Z

The following code prints all three levels of snapshots. I hope this will help:

self.databaseRef.child("cookies").observeSingleEvent(of: .value, with: { (cookiesSnapshot) in print("cookies snapshot: \(cookiesSnapshot)") self.databaseRef.child("dessert").observeSingleEvent(of: .value, with: { (dessertSnapshot) in print("dessert snapshot: \(dessertSnapshot)") self.databaseRef.child("breakfast").observeSingleEvent(of: .value, with: { (breakfastSnapshot) in print("breakfast snapshot: \(breakfastSnapshot)") }) }) })

I can't check this, so I hope all the } and ) are at the right place. :)

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