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
}
Related
I am wanting to capture all the values in my childByAutoId in firebase. Essentially, it stores all the items that a person has shortlisted. However, I do not seem to be capturing this, and I assume it is because I am not calling the snapshot correctly to factor the auto id's.
Database:
userID
-> Favourited
-> Auto Id
-> itemName: x
-> Auto Id
-> itemName: x
-> Auto Id
-> itemName: x
Code:
func retrieveItems() {
guard let userId = Auth.auth().currentUser?.uid else { return }
let ref = Database.database().reference().child("users/\(userId)/Favourited")
ref.observe(.value, with: { (snapshot) in
if snapshot.childrenCount>0 {
self.favUsers.removeAll()
for likes in snapshot.children.allObjects as! [DataSnapshot] {
let likesObject = likes.value as? [String: AnyObject]
let itemName = likesObject!["itemName"]
let likesList = Names(id: likes.key, itemName: itemName as! String?)
self.favUsers.append(likesList)
}
} else {
print("not yet")
}
})
self.favList.reloadData()
}
Could someone have a look and let me know what I may be doing wrong? Thank you!
This happens because Firebase loads data asynchronously, and right now you're calling reloadData before the self.favUsers.append(likesList) has ever run.
The call to reloadData needs to be inside the close/completion handler that is called when the data comes back from Firebase:
ref.observe(.value, with: { (snapshot) in
if snapshot.childrenCount>0 {
self.favUsers.removeAll()
for likes in snapshot.children.allObjects as! [DataSnapshot] {
let likesObject = likes.value as? [String: AnyObject]
let itemName = likesObject!["itemName"]
let likesList = Names(id: likes.key, itemName: itemName as! String?)
self.favUsers.append(likesList)
}
self.favList.reloadData() // 👈 Move this here
} else {
print("not yet")
}
})
I also recommend checking out some of these answers asynchronous data loading in Firebase.
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]
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 now a observe handle that will check when new channels are added. I want it to be a observeSingleEvent with a button which will reload the channels when the user clicks on it. The observeSingleEvent is working correctly. This is the code:
private func observeChannels() {
channelRefHandle = channelRef.observe(.childAdded, with: { (snapshot) -> Void in
self.playersInChannnel.append("\(snapshot.childrenCount)")
let channelData = snapshot.value as! Dictionary<String, AnyObject>
let id = snapshot.key
if let name = channelData["name"] as! String!, name.characters.count > 0 {
self.channels.append(Channel(id: id, name: name))
self.tableView.reloadData()
} else {
print("Error! Could not decode channel data")
}
})
}
I now tried converting it to observeSingleEvent, put the print is saying Error, could not decode channel data. This is my code:
func reloadChannels()
{
channelRef.observeSingleEvent(of: .value, with: { (snapshot) -> Void in
self.playersInChannnel.append("\(snapshot.childrenCount)")
let channelData = snapshot.value as! Dictionary<String, AnyObject>
let id = snapshot.key
if let name = channelData["name"] as! String!, name.characters.count > 0 {
self.channels.append(Channel(id: id, name: name))
self.tableView.reloadData()
} else {
print("Error! Could not decode channel data")
}
})
}
What is wrong with this code? This is a print of the snapshot from observeSingleEvent:
Snap (channels) {
"-Ke3g8tLH9A-_iTVjQhq" = {
"-Ke3g8tO2XPCbyIjP4Op" = {
PictureVersion = "";
userID = keVlTMUXyRViUsTVjTnKdvZs7mg1;
username = pietje;
};
name = test;
};
"-Ke3gFbijlcQGuJXe42L" = {
"-Ke3gFbjsEgpA3wjM1Jv" = {
PictureVersion = "";
userID = keVlTMUXyRViUsTVjTnKdvZs7mg1;
username = pietje;
};
name = test2;
};
}
Error! Could not decode channel data
Again, firing observeChannels() is showing no errors. Thank you.
You didn't just change from observe to observeSingleEvent, you also switched from observing .childAdded to observing .value. And since you're now listening for a .value, that means that the snapshot you get contains all the child nodes at once (even if there's only one matching child).
For this reason, you will need to loop over the children of the snapshot, to get the channel data you had before:
func reloadChannels()
{
channelRef.observeSingleEvent(of: .value, with: { (snapshot) -> Void in
self.playersInChannnel.append("\(snapshot.childrenCount)")
for channelSnap in snapshot.children {
let channelData = (channelSnap as! FIRDataSnapshot).value as! Dictionary<String, AnyObject>
let id = (channelSnap as! FIRDataSnapshot).key
if let name = channelData["name"] as! String!, name.characters.count > 0 {
self.channels.append(Channel(id: id, name: name))
self.tableView.reloadData()
} else {
print("Error! Could not decode channel data")
}
}
})
}
See the answers to this question for more on how to loop over the children of a snapshot: Iterate over snapshot children in Swift (Firebase)
I am trying to parse data from Firebase into an array of objects, and upon completion display the text from the first object in the array. However, I can't work out/find a solution to stop the code continuing before the download is complete. So it proceeds to update the user's completion to true, without displaying the text. This is the function as is, the downloading and appending to array works fine, but it skips to displayNextInSeries() before it's finished...
func parseSeries (ref: String) {
FIRDatabase.database().reference().child("library").child("series").child(ref).observeSingleEvent(of: .value, with: { (snapshot) in
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {
for snap in snapshot {
print(snap)
if let pushSeriesDict = snap.value as? Dictionary<String, AnyObject> {
let key = snap.key
let push = PUSH_SERIES(pushKey: key, pushSeriesData: pushSeriesDict)
self.seriesArray.append(push)
}
}
}
})
print("\(ref) Series Count: \(self.seriesArray.count)")
displayNextInSeries()
}
The display next in series function sees the seriesArray.count = 0, so it doesn't update the texLbl:
func displayNextInSeries() {
if seriesProgress < seriesArray.count {
animateProgress(current: seriesProgress, total: seriesArray.count)
currentPUSH_SERIES = seriesArray[seriesProgress]
currentPUSH_SERIES.text = personaliseText(text: currentPUSH_SERIES.text)
textLbl.animateUpdate(currentPUSH_SERIES.text, oldText: previousText)
titleLbl.text = "\(currentPUSH_SERIES.title!)"
previousText = currentPUSH_SERIES.text
seriesProgress += 1
} else {
animateProgress(current: sessionProgress, total: sessionTarget)
titleLbl.text = ""
greetingPush()
seriesPlay = false
seriesProgress = 0
user.updateProgress(seriesName)
print(user.progress)
}
}
I may be doing something fundamentally wrong here. Your help is much needed and much appreciated! Thanks, Matt
The observeSingleOfEvent is an asynchronous call, calling the function inside the completionBlock will solve it,The problem is that your print function is being called even before observeSingleOfEvent is finished downloading data :-
func parseSeries (ref: String) {
FIRDatabase.database().reference().child("library").child("series").child(ref).observeSingleEvent(of: .value, with: { (snapshot) in
if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {
for snap in snapshot {
print(snap)
if let pushSeriesDict = snap.value as? Dictionary<String, AnyObject> {
let key = snap.key
let push = PUSH_SERIES(pushKey: key, pushSeriesData: pushSeriesDict)
self.seriesArray.append(push)
print("\(ref) Series Count: \(self.seriesArray.count)")
displayNextInSeries()
}
}
}
})
}