如何将 Firebase 中的用户个人列表抓取到表格视图

Question

我试图简单地将用户喜欢的地图获取到表格视图上。 我认为这是非常基本的东西，但结果非常困难。

这里的代码是我迄今为止管理的最好的代码，试图以某种方式引用一个(用户 id(和一个(你的地图 id(来获取特定信息。

例如。由于用户已经将 1 张地图设为他的最爱(带有 id (-LpY4XEER-b21hwMi9sp((。我想浏览root["yourmap"]中的所有地图，并且只将他的地图获取到表格视图上。

火力基地

"users" {
"6g55cHXH4begwooHQvO4EKNV3xm1" : {
"photoURL" : "https://firebasestorage.googleap...",
"username" : "lbarri",
"yourmaps" : {
"-LpY4XEER-b21hwMi9sp" : true
}
}
}

"yourmaps": {
"-LpY4XEER-b21hwMi9sp" : {
"author" : {
"photoURL" : "https://firebasestorage.googleapis.com/v...",
"uid" : "6g55cHXH4begwooHQvO4EKNV3xm1",
"username" : "lbarri"
},
"mapmoderators" : {
"6g55cHXH4begwooHQvO4EKNV3xm1" : true
},
"mapphotoURL" : "https://firebasestorage.googleapis...",
"mapusername" : "Hello World"
},
"-LpYo_pQ8zIOGHHlNU1Q" : {
"author" : {
"photoURL" : "https://firebasestorage.googleapis.com/v...3",
"uid" : "RLFK9xnvhccTu2hbNHq0v05J2A13",
"username" : "lbarri"
},
"mapmoderators" : {
"RLFK9xnvhccTu2hbNHq0v05J2A13" : true
},
"mapphotoURL" : "https://firebasestorage.googleapis.com/...",
"mapusername" : "Dream"
}
}

迅速

func getCurrentUserMaps() {
guard let userProfile = UserService.currentUserProfile else { return }
let currentUserId = userProfile.uid
let userRef = Database.database().reference().child("users").child(currentUserId)
userRef.observeSingleEvent(of: .value, with: { (snapshot) in
let root = snapshot.value as? NSDictionary
if let mapsByUser = root!["yourmaps"] as? [String: Bool] {
for (documentId, status) in mapsByUser {
if status {
// Document is true, check for the maps
self.fetchyourmaps(key: documentId, owner: currentUserId)
}
}
}
}) { (error) in
print(error.localizedDescription)
}
}
func fetchyourmaps(key:String, owner:String) {
let yourMapRef = Database.database().reference().child("yourmaps")
yourMapRef.observeSingleEvent(of: .value, with: {snapshot in
let user = snapshot.value as? NSDictionary
if let mapsByUser = user!["mapmoderators"] as? [String: Bool] {
for (userId, status) in mapsByUser {
if userId == owner && status == true {
print("Owner (owner) manages this (user)")
var tempYourMap = [YourMapProfile]()
for key in (snapshot.value as? NSDictionary)! {
let childSnapshot = key as? DataSnapshot
let dict = childSnapshot!.value as? [String:AnyObject]                           
let author = dict!["author"] as? [String:AnyObject]
let uid = author!["uid"] as? String      
let username = author!["username"] as? String
let photoURL = author!["photoURL"] as? String
let url = URL(string:photoURL!)
let mapusername = dict!["mapusername"] as? String
let mapphotoURL = dict!["mapphotoURL"] as? String
let mapurl = URL(string:mapphotoURL!)
let userProfile = UserProfile(uid: uid!, username: username!, photoURL: url!, mapPoints: mapPoints!)
let yourmapprofile = YourMapProfile(mapid: childSnapshot!.key as! String, mapauthor: userProfile, mapusername: mapusername!, mapphotoURL: mapurl!)
tempYourMap.append(yourmapprofile)
}
self.yourmaps = tempYourMap
self.tableView.reloadData()
}
}
}
})
}

print("Owner (owner) manages this (user)")确实将正确的地图打印到控制台上

在那行之后，就是我无法弄清楚如何将信息打包到我的表视图中的时候。

我已经到处搜索有关将一个根文件夹引用到另一个根文件夹时如何从Firebase检索数据的信息，但我找不到任何有用的东西。因此，任何链接/指南/教程等将不胜感激，我很乐意从那里获取它。这至少是你应该这样做的吗？

Answer 1

有几种方法可以做到这一点，但这里有两种： 选项 1 是利用深度查询来获取此用户最喜欢的地图。第二种是遍历用户地图并一次拉取每个地图。

选项 1：

从这样的映射节点开始

allMaps
map_0
favorite_of
uid_0: true
uid_3: true
map_user_name: "Larry"
map_1
favorite_of
uid_2: true
map_user_name: "Moe"
map_2
favorite_of
uid_0: true
map_user_name: "Curly"

然后，进行深度查询以获取所有喜欢的uid_0地图

func queryToGetMyFavoriteMaps() {
let uid = "uid_0"
let ref = self.ref.child("allMaps")
let path = "favorite_of/" + uid
let query = ref.queryOrdered(byChild: path).queryEqual(toValue: true)
query.observeSingleEvent(of: .value, with: { snapshot in
for child in snapshot.children {
print(child) //prints the map_0 & map_2 nodes since that's the favorite onces
}
})
}

选项 2

更改 allMaps 节点，因为我们不会执行查询

allMaps
map_0
map_user_name: "Larry"
map_1
map_user_name: "Moe"
map_2
map_user_name: "Curly"

然后用户节点将是这样的

users
uid_0
name: "Frank"
favorite_maps:
map_0: true
map_2: true
uid_1
name: "Leroy"
favorite_maps:
map_1: true

然后读取uid_0的favorite_maps节点并从该快照获取密钥的代码，然后迭代它们，一次读取一个映射节点。

func iterateToGetFavoriteMaps() {
let uid = "uid_0"
let userRef = self.ref.child("users").child(uid)
userRef.observeSingleEvent(of: .value, with: { snapshot in
if let mapRefs = snapshot.childSnapshot(forPath: "favorite_maps").value as? [String: Any] {
let mapKeys = mapRefs.keys //note mapKeys is a Dict so we can directly access the keys
for key in mapKeys {
let mapRef = self.ref.child("allMaps").child(key)
mapRef.observeSingleEvent(of: .value, with: { mapSnapshot in
let name = mapSnapshot.childSnapshot(forPath: "mapUserName").value as? String ?? "No Name"
print(name)
})
}
}
})
}