Basically everything is working, except the showChild func is returning completion([]) because of the guard catData = Category(snapshot: catInfo). I am wondering why the guard let is returning completion. When I debug, catInfo does have 1 value as shown in my pic of database and I want to append catData.main to "cats". Below is code for the service method and Category model as well.
Firebase Database
static func showChild(completion: #escaping ([String]) -> Void) {
let ref = Database.database().reference().child("category").child(User.current.uid)
ref.observeSingleEvent(of: .value, with: { (snapshot) in
guard let snapshot = snapshot.children.allObjects as? [DataSnapshot] else {
return completion([])
}
var cats = [String]()
for catInfo in snapshot {
guard let catData = Category(snapshot: catInfo) else {
return completion([])
}
cats += catData.main
}
completion(cats)
})
}
import Foundation
import FirebaseDatabase.FIRDataSnapshot
class Category {
var key: String?
let main: [String]
init?(snapshot: DataSnapshot) {
guard !snapshot.key.isEmpty else {return nil}
if let dict = snapshot.value as? [String : Any]{
let main = dict["main"] as? [String]
self.key = snapshot.key
self.main = main ?? [""]
}
else{
return nil
}
}
}
The issue is pretty straightforward.
While your snapshot contains at least one node of data, it's not in a format that the Category init method understands. You're iterating over it's child nodes and in your screenshot, there's only one, with a key of 'main'
You are observing this node
fb_root
category
2ayHe...
and then you're iterating over it's child nodes which will be
main
0: Performance
so the key is 'main' and it's value is '0: Performance'
but your Category class is looking for a child node of 'main'
let main = dict["main"] as? [String]
There's not enough info to understand what will be contained in the rest of the structure so I can't tell you how to correct it, but at least you know what the problem is.
To clarify, this line
if let dict = snapshot.value as? [String : Any]
will make dict = [0: "Performance]
Related
I've got a code which normally should return to me a value from Firebase.
My Firebase struct is :
Experience{
UserId{
LDG_DAY: "4"
LDG_NIGHT: "0"
APCH_IFR: "0"
}
}
My code is :
func getUserExp(){
let ref = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
let Date = self.flightDate.text
ref.child("Experience")/*.child(userID!)*/.observeSingleEvent(of: .value) {(snapshot) in
if snapshot.hasChild(userID!){
let value = snapshot.value as? NSDictionary
let ldg_day = value?["LDG_DAY"] as? String ?? "123"
let ldg_night = value?["LDG_NIGHT"] as? String ?? "0"
let apch_ifr = value?["APCH_IFR"] as? String ?? "0"
self.intLdgDay = Int(ldg_day)!
self.intLdgNight = Int(ldg_night)!
self.intApchIfr = Int(apch_ifr)!
print("string = \(ldg_day) int = \(self.intLdgDay)")
}
}
}
Now the code didn't work as I would like... In fact my code return the basic as? String ?? "123" value but the snapshot.value get the good value from firebase ...
What's wrong ? I use this code for many other part of my app and no problems about it ?
Thanks for your help
I believe you want to ensure the node exists before trying to read the child data.
NOTE:
I see the path to read has the uid commented out so it's unclear if you intended to read a single user (leaving in the uid) or if you actually wanted to load every user at one time (thousands). This answer assumes you are intending to read that specific user node only. See #Callam answer if you intended to read ALL of the users nodes at one time.
The code you have now is using snapshot.hasChild which looks within the node to see if the child, the users uid exists, and it doesn't so the code will always fail.
if snapshot.hasChild(userID!)
I think what you want to do is use snapshot.exists to ensure it's a valid node before reading. Here's the code:
let experienceRef = self.ref.child("Experience")
let usersExpRef = experienceRef.child(uid)
usersExpRef.observeSingleEvent(of: .value) { snapshot in
if snapshot.exists() {
let value = snapshot.value as! [String: Any]
let ldg_day = value["LDG_DAY"] as? String ?? "123"
print("string = \(ldg_day)")
} else {
print("the \(uid) node does not exist")
}
}
I would also suggest safely unwrapping options before attempting to work with them as they could be nil, and that would crash your code.
guard let thisUser = Auth.auth().currentUser else { return }
let uid = thisUser.uid
Note I also replaced the old objc NSDictionary with it's Swifty counterpart [String: Any]
Assuming your struct is from the root, and Experience contains more than one user ID, your code is currently observing the value for all user IDs since the /*.child(userID!)*/ is commented out.
Therefore you are requesting every user's experience and checking on the client if the current user exists as a child – this will succeed if the current user's ID is present at Experience/$uid.
ref.child("Experience")/*.child(userID!)*/.observeSingleEvent(of: .value) { (snapshot) in
if snapshot.hasChild(userID!) {
let value = snapshot.value as? NSDictionary
Now we have a snapshot with all Experiences and we've confirmed that it has a child for the current user's ID – we would need to get that child and cast the value of that to a dictionary.
let value = snapshot.childSnapshot(forPath: userID).value as? NSDictionary
This fixes the issue but obviously, we don't want to download every experience on a single user's device, and they maybe shouldn't even have the permission to request that reference location either.
So if you uncomment .child(userID!), the snapshot will be of just one Experience, so snapshot.hasChild(userID!) will fail. Instead, you can use snapshot.exists() and/or a conditional cast to determine if the snapshot for the userID is existent and/or thereby castable.
func getUserExp() {
let ref = Database.database().reference()
let userID = Auth.auth().currentUser?.uid
let Date = self.flightDate.text
ref.child("Experience").child(userID!).observeSingleEvent(of: .value) { snapshot in
if snapshot.exists() {
let value = snapshot.value as? [String:String]
let ldg_day = value?["LDG_DAY"] ?? "123"
let ldg_night = value?["LDG_NIGHT"] ?? "0"
let apch_ifr = value?["APCH_IFR"] ?? "0"
self?.intLdgDay = Int(ldg_day)!
self?.intLdgNight = Int(ldg_night)!
self?.intApchIfr = Int(apch_ifr)!
print("string = \(ldg_day) int = \(self.intLdgDay)")
} else {
print("experience for \(snapshot.key) doesn't exist")
}
}
}
You can clean this up a bit with a struct and extension.
// Experience.swift
struct Experience {
var ldg_day: String
var ldg_night: String
var apch_ifr: String
}
extension Experience {
static var currentUserRef: DatabaseReference? {
return Auth.auth().currentUser.flatMap {
return Database.database().reference(withPath: "Experience/\($0.uid)")
}
}
init?(snapshot: DataSnapshot) {
guard snapshot.exists() else { return nil }
let value = snapshot.value as? [String:String]
self.ldg_day = value?["LDG_DAY"] ?? "123"
self.ldg_night = value?["LDG_NIGHT"] ?? "0"
self.apch_ifr = value?["APCH_IFR"] ?? "0"
}
}
Et voilà,
func getUserExp() {
Experience.currentUserRef?.observeSingleEvent(of: .value, with: { [weak self] in
if let experience = Experience(snapshot: $0) {
self?.intLdgDay = Int(experience.ldg_day)!
self?.intLdgNight = Int(experience.ldg_night)!
self?.intApchIfr = Int(experience.apch_ifr)!
print("string = \(experience.ldg_day) int = \(self.intLdgDay)")
} else {
print("experience for \($0.key) doesn't exist")
}
})
}
My Firebase Database
More specifically, I have randomly generated children(Listings) and from those randomly generated Listings I would like to get the string value from the keys.
For example, if I wanted the Photo URL address, I would like to get the string value of the key "PhotoURL:".
Thank you in advance !
First you need to do is to import Firebase and then call a function from the Database class like so:
let ref = Database.database().reference().child("Listings")
You can call child recursively to go deeper into your tree
//.child("Listings").child("SomeListing").child("PhotoURL")
Then call observeSingleEvent to receive the values from firebase.
Your value is stored in the snapshot variable
ref.observeSingleEvent(of: .value, with: { (snapshot) in
guard let listingsDictionary = snapshot.value as? [String: Any] else { return }
listngsDictionary.forEach({ (key, value) in
// Here you can iterate through it
})
}) { (err) in
print("Failed to fetch following listings:", err)
}
Here is the code to get child values from Listings.
var ListArr = [ListModel]()
let ref = Database.database().reference().child("Listings")
ref.observe(.childAdded, with: { (snapshot) in
print(snapshot)
guard let dictionary = snapshot.value as? [String : AnyObject] else {
return
}
let Obj = ListModel()
Obj.UID = snapshot.key
Obj.PhotoURL = dictionary["PhotoURL"] as? String
self.ListArr.append(Obj)
}, withCancel: nil)
}
You can set up the model class
class ListModel: NSObject {
var UID:String?
var PhotoURL:String?
}
I have two observers, the second observer is dependent on the first observers value. I can't seem to get the first observer to work, I am not getting any errors on Xcode. The first function has to check the Users profile for information and then use that information to search for different information in the database. Here is my code:
func loadposts() {
ref = Database.database().reference()
let trace = Performance.startTrace(name: "test trace")
trace?.incrementCounter(named:"retry")
let userID = Auth.auth().currentUser?.uid
print(userID!)
ref.child("Users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
// Get user value
let value = snapshot.value as? NSDictionary
let one1 = value?["Coupon Book"] as? String ?? ""
print("one1: \(one1)")
self.bogus.set(one1, forKey: "bogus")
}) { (error) in
print(error.localizedDescription)
}
delay(0.1) {
print("bogus: \(self.bogus.string(forKey: "bogus"))")
Database.database().reference().child("Coupons").child(self.bogus.string(forKey: "bogus")!).observe(.childAdded) { (Snapshot : DataSnapshot) in
if let dict = Snapshot.value as? [String: Any] {
let captiontext = dict["company name"] as! String
let offerx = dict["offer count"] as! String
let logocomp = dict["logo"] as! String
let actchild = dict["childx"] as! String
let post = Post(captiontext: captiontext, PhotUrlString: actchild, offertext: offerx, actualphoto: logocomp)
self.posts.append(post)
self.tableview.reloadData()
print(self.posts)
}
}
}
trace?.stop()
}
Any help is appreciated.
self.bogus.string(forKey: "bogus"))" is nil because observeSingleEvent is an async method, so to get the required results you need to call the second observer inside the first observer or you can use the completion handler
You can use the completionHandler like this:
guard let uid = Auth.auth().currentUser?.uid else {
return
}
func firstObserverMethod(completionCallback: #escaping () -> Void) {
ref.child("Users").child(uid).observeSingleEvent(of: .value, with: { (snapshot) in
// Get user value
if let value = snapshot.value as? [String: Any] {
let one1 = value["Coupon Book"] as? String
print("one1: \(one1)")
self.bogus.set(one1, forKey: "bogus")
completionCallback()
}
}) { (error) in
print(error.localizedDescription)
}
}
Now using the above method:
firstObserverMethod {
print("bogus: \(self.bogus.string(forKey: "bogus"))")
guard let bogusString = self.bogus.string(forKey: "bogus") else {
print("bogus is not set properly")
return
}
Database.database().reference().child("Coupons").child(bogusString).observe(.childAdded) { (Snapshot : DataSnapshot) in
if let dict = Snapshot.value as? [String: Any] {
let captiontext = dict["company name"] ?? ""
let offerx = dict["offer count"] ?? ""
let logocomp = dict["logo"] ?? ""
let actchild = dict["childx"] ?? ""
let post = Post(captiontext: captiontext, PhotUrlString: actchild, offertext: offerx, actualphoto: logocomp)
self.posts.append(post)
DispatchQueue.main.async {
self.tableview.reloadData()
}
print(self.posts)
}
}
}
Note: You should use optional binding to get the values from optional
Since you are using the result of the 1st observer in the reference of your 2nd observer, it's a very bad idea to add the 2nd observer right below the first observer. And adding a delay won't be a viable solution : these two calls are asynchronous, which means that the reason why you are not getting might very likely be because the 2nd observer is triggered even before the 1st has returned any data.
The solution here, would be using a completion handler, or you could just incorporate your 2nd observer inside the completion block of the 1st, to be make sure that the proper order (1st observer -> 2nd observer) will always be respected.
It would look somehow like this:
func loadposts() {
// ...
// 1st Observer here
ref.child("Users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
// Get your value here
guard let one1 = snapshot.childSnapshot(forPath: "Coupon Book").value as? String else { return }
// 2nd Observer here. Now you can use one1 safely:
Database.database().reference().child("Coupons").child(one1).observe(.childAdded) { (Snapshot : DataSnapshot) in
// ...
}
})
}
Now, a couple of things that you could also improve in your code, while not directly related to the question:
I would suggest you to make use of guard statements instead force-unwrapping, which may end up in crashing your app at some point.
For example, you could check whether your current user exist or not like so:
guard let currentUserID = Auth.auth().currentUser?.uid else {
return
}
// Now you can use safely currentUserID
Also, when you try to get the data out of the snapshot, it's not a good idea either, to use force-casting. You would better write it in this way:
yourRef.observeSingleEvent(of: .value, with: { (snapshot) in
for child in snapshot.children.allObjects as! [DataSnapshot] {
guard let text = child.childSnapshot(forPath: "text").value as? String, let somethingElse = child.childSnapshot(forPath: "otherValue").value as? NSNumber else {
return
}
// And so on, depending of course on what you have in your database.
}
I have this code below in order to retrieve a list of restaurants and their data. However, it's not storing the data, and every time I try to return the array it returns nil. But if I print it, prints the data. Any suggestions?
func getRestaurants()-> Array<Restaurant>{
var baruri = [Restaurant]()
dataBaseRef.child("AthensRestaurants/Restaurants").observe(.value, with: { (snapshot) in
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {
for snap in snapshot {
print(snap)
if let restaurantData = snap.value as? Dictionary<String, AnyObject> {
let restaurant = Restaurant(restaurantData: restaurantData)
baruri.append(restaurant)
print(baruri)
}
}
}
})
return baruri
}
The firebase observe is an asynchronous callback function, so it will run after it is finished. In other words, your return baruri will always runs before the value got back. You can use completion handler to get the value you want.
var restaurants = [Restaurant]()
func getRestaurants(completion: #escaping (Array<Restaurant>) -> Void){
var baruri = [Restaurant]()
dataBaseRef.child("AthensRestaurants/Restaurants").observe(.value, with: { (snapshot) in
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {
for snap in snapshot {
print(snap)
if let restaurantData = snap.value as? Dictionary<String, AnyObject> {
let restaurant = Restaurant(restaurantData: restaurantData)
baruri.append(restaurant)
print(baruri)
completion(baruri)
}
}
}
})
}
// Call this function with call back
getRestaurants { restaurants in
self.restaurants = restaurants
}
I am using the subscript in the following code incorrectly for this Firebase data pull, but I can't figure out what I am doing wrong. I get an error of Ambiguous use of subscript for the let uniqueID = each.value["Unique ID Event Number"] as! Int line.
// Log user in
if let user = FIRAuth.auth()?.currentUser {
let uid = user.uid
// values for vars sevenDaysAgo and oneDayAgo set here
...
let historyRef = self.ref.child("historyForFeedbackLoop/\(uid)")
historyRef.queryOrdered(byChild: "Unix Date").queryStarting(atValue: sevenDaysAgo).queryEnding(atValue: oneDayAgo).observeSingleEvent(of: .value, with: { snapshot in
if (snapshot.value is NSNull) {
print("user data not found")
}
else {
if let snapDict = snapshot.value as? [String:AnyObject] {
for each in snapDict {
// Save the IDs to array.
let uniqueID = each.value["Unique ID Event Number"] as! Int
self.arrayOfUserSearchHistoryIDs.append(uniqueID)
}
}
else{
print("SnapDict is null")
}
}
})
}
I tried to applying what I learned from this post, but I couldn't figure out what I am missing because I thought I was letting the compiler know what type of dictionary it is with the "as? [String:AnyObject]"
Any thoughts or ideas would be greatly appreciated!
My preferred way of dealing with data is to unwrap the FIRDataSnapshot as late as possible.
ref!.observe(.value, with: { (snapshot) in
for child in snapshot.children {
let msg = child as! FIRDataSnapshot
print("\(msg.key): \(msg.value!)")
let val = msg.value! as! [String:Any]
print("\(val["name"]!): \(val["message"]!)")
}
})
Taking Frank's feedback into account, here is the actual working code I used that follows that approach in case it's helpful.
// Log user in
if let user = FIRAuth.auth()?.currentUser {
let uid = user.uid
// values for vars sevenDaysAgo and oneDayAgo set here
...
let historyRef = self.ref.child("historyForFeedbackLoop/\(uid)")
historyRef.queryOrdered(byChild: "Unix Date").queryStarting(atValue: sevenDaysAgo).queryEnding(atValue: oneDayAgo).observeSingleEvent(of: .value, with: { snapshot in
if (snapshot.value is NSNull) {
print("user data not found")
}
else {
for child in snapshot.children {
let data = child as! FIRDataSnapshot
let value = data.value! as! [String:Any]
self.arrayOfUserSearchHistoryIDs.append(value["Unique ID Event Number"] as! Int)
}
}
})
}