I'm using this function to check to see if a certain handle exists in my database. It works fine for the most part - if the handle exists, it updates the table view to display that user. However if there is no match for the handle entered, my alert view is not showing up.
// Search DB for matching handles
#IBAction func searchHandleButtonPressed(_ sender: Any) {
if let handleToSearch = handleSearchTextField.text?.lowercased() {
let databaseRef = FIRDatabase.database().reference()
databaseRef.child("users").queryOrdered(byChild: "lowercaseHandle").queryEqual(toValue: handleToSearch).observeSingleEvent(of: .value, with: { (snapshot) in
if let snapDict = snapshot.value as? [String:AnyObject] {
for each in snapDict{
let key = each.key
let handle = each.value["handle"] as! String
self.returnedHandles.removeAll()
self.returnedHandles.append(handle)
let pic = each.value["profilePicture"] as! String
self.returnedUsersProfilePic = pic
self.returnedUsersUID = key
if handle.lowercased() != handleToSearch {
self.noHandleFoundAlert()
}
if handle != "" {
DispatchQueue.main.async {
self.getFriendsInfo()
self.tableView.reloadData()
}
}
}
}
}, withCancel: {(Err) in
// print(Err.localizedDescription)
})
}
}
I put the alert in the loop as:
if handle.lowercased() != handleToSearch {
self.noHandleFoundAlert()
}
But obviously this isn't the correct approach as it isn't working. If I enter a random string of characters, or a handle that I know isn't in use, the alert doesn't come up. Where else would I put the alert so it will show up if there's no match?
The snapshot will be converted to an empty dictionary with your current code.
Before converting the snapshot.value to a Dictionary, check if it exists with snapshot.exists(): https://firebase.google.com/docs/reference/ios/firebasedatabase/api/reference/Classes/FIRDataSnapshot#-exists
You first have to check if the query you made, has data. So you have a
.hasChild("handle")
it returns a boolean, so when is true you do the loop, else notified user.
Related
I've Firebase Database where each user has own email and username. How to check unique username? I tried to make it like this, but my code doesn't work properly therefore different users can have the same username
usernameField.isHidden = false
let username:String = self.usernameField.text!
if (usernameField.text?.isEmpty == false){
ref.child("users").queryOrdered(byChild("username").queryEqual(toValue: username).observeSingleEvent(of: .value, with: { snapshot in
if snapshot.exists(){
print("username exist")
}else{
ref.root.child("users").child(userID).updateChildValues(["username": username])
}
})
}
I'm a little bit newbie in Firebase I store email and username for each user like this newUserReference.setValue(["username":String(), "email" : self.emailTextField.text!]). On next view, user can type username in usernameField.text and this value will be added in Firebase Database. But if the next user (user 2) will type the same username like previous user, it must be blocked, because username should be unique
You still need to indicate what property you want to order/filter on with queryOrdered(byChild:):
if (usernameField.text?.isEmpty == false){
ref.child("users").queryOrdered(byChild:"username").queryEqual(toValue: username).observeSingleEvent(of: .value, with: { snapshot in
if snapshot.exists(){
If you're trying to store your user's id on login do this when you receive a successful response to the login:
create a Shared Instance to store the ID
class userDataSource {
var id : String? // variable to store your users ID
static let sharedInstance = PageDataSource() // global access to this dataSource
private init() {}
}
Assign the id a value after successful login
func getIDFromLogin() {
if let user = Auth.auth().currentUser {
print(user.uid)
userDataSource.sharedInstance.id = user.uid
}
}
Then you can do this to view each id:
ref.child("users").observeSingleEvent(of: .value, with: { snapshot in
if let snapshots = snapshot.children.allObjects as? [DataSnapshot] {
for snap in snapshots {
print(snap.key) // you can compare userDataSource.sharedInstance.id to this value
}
}
})
Or if you just want that user's data do this:
ref.child("users").child(userDataSource.sharedInstance.id!).observeSingleEvent(of: .value, with: { snapshot in
if let snapshots = snapshot.children.allObjects as? [DataSnapshot] {
for snap in snapshots {
print(snap)
}
}
})
Edit to answer your question more accurately
Here is an answer more inline with your question. First thing I will recommend is for you to add a table to Firebase that only contains the usernames, and the .uid's that they belong to. You will need to first read through that table to make sure that no one else has that username, then update the table accordingly:
// This function will check through all of the usernames and return a true or false value in the completion handler
func checkUsernames(_ completion: #escaping(_ success: Bool) -> Void) {
ref.child("usernames").observeSingleEvent(of: .value, with: { snapshot in
if let snapshots = snapshot.children.allObjects as? [DataSnapshot] {
for snap in snapshots {
if snap.value == username {
completion(false)
}
}
completion(true)
} else {
completion(true) // TODO: check for errors before setting completion
}
})
}
// this function will set the username values in Firebase
func storeUsername() {
let usernameRef = ref.child("usernames")
usernameRef.updateChildValues(["\(userDataSource.sharedInstance.id!)" : username])
}
}
}
Assuming you have already handled your username variable and set it's value, you will call the functions like this:
checkUsernames({ (success) in
if success {
storeUsername()
// you may also want to update your "users" table here as well
} else { print("Duplicate Username") } // handle alert or something here
})
I am making a completion handler for a function which will return a list of objects. When it return value for first time, it works well. But when any change happen into firebase database and again observe gets called, array size gets doubled up. Why it's getting doubled up?
func getStadiums(complition: #escaping ([Stadium]) -> Void){
var stadiums: [Stadium] = []
let stadiumRef = Database.database().reference().child("Stadium")
stadiumRef.observe(.value, with: { (snapshot) in
for snap in snapshot.children {
guard let stadiumSnap = snap as? DataSnapshot else {
print("Something wrong with Firebase DataSnapshot")
complition(stadiums)
return
}
let stadium = Stadium(snap: stadiumSnap)
stadiums.append(stadium)
}
complition(stadiums)
})
}
And calling like this
getStadiums(){ stadiums
print(stadiums.count) // count gets doubled up after every observe call
}
The code you're using declares stadiums outside of the observer. This means any time a change is made to the value of the database reference, you're appending the data onto stadiums without clearing what was there before. Make sure to remove the data from stadiums before appending the snapshots again:
func getStadiums(complition: #escaping ([Stadium]) -> Void){
var stadiums: [Stadium] = []
let stadiumRef = Database.database().reference().child("Stadium")
stadiumRef.observe(.value, with: { (snapshot) in
stadiums.removeAll() // start with an empty array
for snap in snapshot.children {
guard let stadiumSnap = snap as? DataSnapshot else {
print("Something wrong with Firebase DataSnapshot")
complition(stadiums)
return
}
let stadium = Stadium(snap: stadiumSnap)
stadiums.append(stadium)
}
complition(stadiums)
})
}
This line stadiumRef.observe(.value, with: { (snapshot) in ... actually adding an observer that will be called everytime your stadium data is changed.
Because you called it twice by using getStadiums(){ stadiums ..., the total observer added will be 2.
That makes the line stadiums.append(stadium) called twice in the second call.
My suggestion would be to use stadiumRef.observe() once without calling it from getStadiums().
Create a Model as below
class OrderListModel: NSObject {
var Order:String?
var Date:String?
}
Use the below code in the view controller and you should be able to see content in your tableview
func getOrdersData() {
self.orderListArr.removeAll()
let ref = Database.database().reference().child(“users”).child(user).child("Orders")
ref.observe(.childAdded, with: { (snapshot) in
print(snapshot)
guard let dictionary = snapshot.value as? [String : AnyObject] else {
return
}
let orderObj = OrderModel()
orderObj.Order = dictionary[“Order”] as? String
orderObj.Date = dictionary[“Date”] as? String
self.orderListArr.append(orderObj)
self.tableView.delegate = self
self.tableView.dataSource = self
self.tableView.reloadData()
}, withCancel: nil)
}
func ListenForChildrenAdded() {
let registerToListenTo = "YourPathHere"
ref.child(registerToListenTo).observeSingleEvent(of: .value) { (snapshot) in
let initialChildren = snapshot.childrenCount
var incrementer = 0
ref.child(registerToListenTo).observe(.childAdded, with: { (snapshot) in
incrementer += 1
print("snapshot: \(snapshot.key) #\(incrementer)")
if incrementer == initialChildren {
print("-> All children found")
} else if incrementer > initialChildren {
print("-> Child Was Added - Run Some Code Here")
}
})
}}
func updateFirebase(){
myFun = thisIsMyFunTextView.text
IAm = iAmTextView.text
var profileKey = String()
profileRef.queryOrdered(byChild: "uid").queryEqual(toValue: userID).observe(.value, with:{
snapshot in
for item in snapshot.children {
guard let data = item as? FIRDataSnapshot else { continue }
guard let dict = data.value as? [String: Any] else { continue }
guard let profileKey = dict["profileKey"] else { continue }
self.profileRef.child(profileKey as! String).child("bodyOfIAM").setValue(IAm)
self.profileRef.child(profileKey as! String).child("bodyOfThisIsMyFun").setValue(myFun)
}
})
}
#IBAction func backButtonClicked(_ sender: Any) {
updateFirebase()
DispatchQueue.main.asyncAfter(deadline: .now() + 4, execute: {
self.dismiss(animated: true)
})
}
myFun and IAm are successfully defined by the changes to the textviews by the user. I can't extract the childByAutoID value without triggering this for in loop that does not end once called, continuing even as a new view controller is presented. The "bodyOfThisIsMyFun" vacillates between the old value and the new value during this loop while the "bodyOfIAM" gets correctly redefined right away and stays that way like it should. How do I get the extracted new values to replace the old values here?
I needed to add this line of code at the end of the for...in statement:
self.profileRef.removeAllObservers()
In my iOS app, a user is able to add friends by searching for there unique username.
The user types the username in a textField and I have a textFieldDidChange notification which is fired every time the text changes.
Within that method I then call the Firebase method below to check if the username exists.
func searchFor(_ username: String) {
guard let uid = FIRAuth.auth()?.currentUser?.uid else {
return
}
let lowercaseUsername = username.lowercased()
let ref = FIRDatabase.database().reference()
ref.child(FirebaseDatabaseBranchNames.usernames.rawValue).child(lowercaseUsername).observeSingleEvent(of: .value, with: { [unowned self](snapshot) in
if snapshot.exists() {
if let usernameUid = snapshot.value as? String {
self.isUserAlreadyAFriend(ref, uid: uid, usernameUid: usernameUid)
}
} else {
// username doesn't exist
}
}, withCancel: nil)
}
How can I cancel this method, before performing it again?
When you attach a listener/observer, Firebase returns a handle for that observer. You can subsequently remove the listener/observer by calling ref.removeObserverWithHandle().
So assuming you want at most one observer, you can keep the reference and observer handle in a member field of you class and then use this code in the searchFor method:
if (self.searchHandle != nil) {
self.searchRef.removeObserverWithHandle(searchHandle)
}
self.searchRef = ref.child(FirebaseDatabaseBranchNames.usernames.rawValue).child(lowercaseUsername)
self.searchHandle = self.searchRef.observeSingleEvent(of: .value, with: { [unowned self](snapshot) in
if snapshot.exists() {
if let usernameUid = snapshot.value as? String {
self.isUserAlreadyAFriend(ref, uid: uid, usernameUid: usernameUid)
}
} else {
// username doesn't exist
}
}, withCancel: nil)
Be aware that you won't be saving data transfer with this though, as the most likely result is that the database client simply drops the data that it gets back from the server.
Better you add the "removeAllObservers()" after the observe single event block. It is working for me.
let ref = Database.database().reference().ref.child(XXXX).child(YYYYY)
ref.observeSingleEvent(of: .value, with: { (snapshot) in
}else{
}
}) { (error) in
print(error.localizedDescription)
}
ref.removeAllObservers()
In my app I have a simple user base that looks like this:
What I'm trying to do is to simply fetch this list once, to check wether a username is valid when a new user signs up with a new username.
The thing is that the only ways I found to retrieve data utilize some sort of observer methods, which are not good for me.
The logic I'm trying to achieve (with the retrieving method that doesn't work) :
// When user tries to sign up with a new username
let username = nicknameField.text?.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
self.usersRef.observeEventType(.Value) { (snapshot: FIRDataSnapshot) in
let dict = snapshot.value as! NSDictionary
for val in dict.allValues {
if username == val as! String {
// Present alert
return
}
}
}
self.usersRef.child(username).setValue(username) { (error, dbRef) in
if error == nil {
// Continue
}
}
How can I simply just fetch the list of users once?
Thanks in advance!
I had to change the observeEventType method to observeSignleEventOfType.
I have also updated my code to make it work (regardless):
self.usersRef.observeSingleEventOfType(.Value) { (snapshot: FIRDataSnapshot) in
let dict = snapshot.value as! NSDictionary
for val in dict.allValues {
if username == val as! String {
// Present alert
return
}
else {
self.usersRef.child(username).setValue(username) { (error, dbRef) in
if error == nil {
// Continue
}
}
}