火力地堡循环多级节点
问题描述:
我试图让从具有节点多一个层次,并通过它不能得到一个节点的结果:火力地堡循环多级节点
我检索这样的数据(它完美,但不是为节点所谓的 “项目”):
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!})
}
}
})
}
和数据库看起来是这样的:
"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"
},
我怎样做,当我只知道 “Users_Food_Data” 和用户ID。我只想将它们列在apropiate细胞中。
答
这是我的建议。
首先看你的数据库结构,你现在有这样的事情:
Users_Food_Data
|_userid
|_FoodStruct
|_items
|_id_1
|_data like calories, date...
|_id_2
|_data...
有太多的节点,这种层次的不尊重我们所说非规范化。请记住,Firebase数据库就像NoSQL数据库,与SQL经典数据库相比,它有很大的不同。下面是一个解释的最佳实践进行非规范化的数据库结构:Structure your database
什么,我可以建议是构建数据库,更是这样的:
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...
然后在你的代码,你可以:
- UsersFood节点上有一个单一的事件遵守所有的breakfeast IDS
- 然后用所有breakfeast IDS得到items_id
- 终于得到items_id数据
希望它能帮助你通过你的代码。
编辑1:您还可以遍历子节点通过使用这样的:
for (DataSnapshot snapshot : dataSnapshot.getChildren()) {
//DO WHAT YOU NEED TO DO
}
谢谢!我知道非规范化,我像你说的那样构建我的数据。在这种情况下,我必须直接从节点获取数据。我非常肯定这肯定是一种方式,但我无法弄清楚,现在我在这里呆了两天。你知道任何方式“像循环”如何在这种情况下使用它? –
好的。我编辑我的帖子旨在为循环。 – Arrabidas92
谢谢!我如何在我的代码中使用它来循环“项目”并获得它们的值? –