let value = categoriessegment.titleForSegment(at: categoriessegment.selectedSegmentIndex)
let data = ["price":pricetextfield.text,"Discount":Discounttextfield.text,"Category":value,"Description":descriptiontextfield.text];
// ref.child(currentdate).setValue(data)
ref.child(currentdate).updateChildValues(data as [AnyHashable : Any])
There is no way in Firebase SDK to only add data if already present, updateChildValues Update previous values or insert new values. To check if data already present you first need to get previous data, then you can check and take your decision. Like
Database.database().reference().observeSingleEvent(of: DataEventType.value, with: { (snapshot) -> Void in
if (snapshot.value != nil) {
// it means data already present
}
})
We have another option to allow/disallow data overwriting through Firebase Rules like
{
"rules": {
"your_node": {
".write": "data.exists()" /// or ".write": "!data.exists()" if you want to restrict overwrite
}
}
}
Related
I am new in programming and in iOS development. I am trying to make an app using Firestore database from Firebase. I don't know if it is normal or not, but when I am trying to get a data from firestore database, it seems too long for me. I don't know if I make a mistake or not
here is my code to get all city data from firestore
reference :
import Foundation
import FirebaseFirestore
import Firebase
enum FirestoreCollectionReference {
case users
case events
case cities
private var path : String {
switch self {
case .users : return "users"
case .events : return "events"
case .cities : return "cities"
}
}
func reference () -> CollectionReference {
return Firestore.firestore().collection(path)
}
}
I use getAllCitiesDataFromFirestore method in CityKM class to get the city data that stored in firestore
class CityKM {
var name : String
var coordinate : GeoPoint
init (name: String , coordinate: GeoPoint ) {
self.name = name
self.coordinate = coordinate
}
init (dictionary: [String:Any]) {
// this init will be used if we get data from firebase observation to construct an event object
name = dictionary["name"] as! String
coordinate = dictionary["coordinate"] as! GeoPoint
}
static func getAllCitiesDataFromFirestore (completion: #escaping ( [CityKM]? )->Void) {
// to retrieve all cities data from Firebase database by one read only, not using realtime fetching listener
let startTime = CFAbsoluteTimeGetCurrent() // to track time consumption of this method
FirestoreCollectionReference.cities.reference().getDocuments { (snapshot, error) in
if let error = error {
print("Failed to retrieve all cities data: \(error.localizedDescription)")
} else {
print("Sucessfully get all cities data from firestore")
guard let documentsSnapshot = snapshot, !documentsSnapshot.isEmpty else {
completion(nil)
return
}
let citiesDocuments = documentsSnapshot.documents
var cityArray = [CityKM]()
for document in citiesDocuments {
guard let cityName = document.data()["name"] as? String,
let cityCoordinate = document.data()["coordinate"] as? GeoPoint else {return}
let theCity = CityKM(name: cityName, coordinate: cityCoordinate)
cityArray.append(theCity)
}
completion(cityArray)
let timeElapsed = CFAbsoluteTimeGetCurrent() - startTime // to track time consumption of this method
print("Time needed to get all cities data from Firestore : \(timeElapsed) s.") // to track time consumption of this method
}
}
}
}
extension CityKM {
// MARK: - User Helper Methods
func toDictionary() -> [String:Any]{
return [
"name" : name,
"coordinate" : coordinate
]
}
}
from my debugging area, it is printed
"Time needed to get all cities data from Firestore : 1.8787678903 s."
is it possible to make it faster? Is 1.8s normal? am i make a mistake in my code that make the request data takes too long time ? I hope that I can make request time is below one second
I don't think the internet speed is the problem, since I can open video on youtube without buffering
That performance sounds a bit worse than what I see, but nothing excessive. Loading data from the cloud simply takes time. A quick approach to hide that latency is by making use of Firebase's built-in caching.
When you call getDocuments, the Firebase client needs to check on the server what the document's value is before it can call your code, which then shows the value to the user. As said: there is no way to speed up this reading in your code, so it'll always take at least 1.8s before the user sees a document.
If instead you listen for realtime updates from the database with addSnapshotListener, the Firebase client may be able to immediately call your code with values from its local cache, and then later re-invoke your code in case there has been an update to the data on the server.
I deleted an entry in the Firestore and also checked it manually to confirm that. However, as long as I do not close the application, I can send a request to fetch the data and I still get the result. This should not be the case.
If you imagine having a shared photo with some textual information and you delete those information, this would mean, other users can still see the textual information (fetched from the Firestore) but not the image anymore (store in Firestorage).
I want to display a message on the UI, something like "The content does not exist anymore".
How I can achieve that? I used the following approach so far but it does not work at the moment:
public func checkIfChallengeObjectExists(completionHandler:#escaping(Bool)->(), challengeId:String) {
CHALLENGE_COLLECTION?.document(challengeId).getDocument(completion: { (querySnapshot, error) in
if (error != nil) {
print(error?.localizedDescription as Any)
}
if (querySnapshot?.documentID == "" || querySnapshot!.metadata.isFromCache) {
completionHandler(false)
}
else {
completionHandler(true)
}
})
}
Any solutions?
Non-existent documents will still return document snapshots, but they will be empty. Therefore, you must check the contents of the snapshot for the document, not the snapshot itself. Also, you should handle errors and the overall flow of the return better.
public func checkIfChallengeObjectExists(completionHandler:#escaping(Bool)->(), challengeId:String) {
CHALLENGE_COLLECTION?.document(challengeId).getDocument(completion: { (querySnapshot, error) in
if let doc = querySnapshot,
doc.exists {
completionHandler(true) // only one possible true condition
} else {
if let error = error {
print(error.localizedDescription)
}
completionHandler(false) // all else false
}
})
}
As a side note, I recommend reordering the parameters of the function to make it easier to read when called (conventionally, the completion handler comes last) and giving the boolean argument a name so it's easier to read when referencing (sometime later or by other developers).
public func verifyChallengeObject(ID: String, _ completion: #escaping (_ exists: Bool) -> Void) {
...
}
verifyChallengeObject(ID: "abc123", { (exists) in
if exists {
...
} else {
...
}
})
I am using Firestore. I am trying to listen for when a new user is added. The problem is, each user also has a friends dictionary. So when I use a snapshot, my code is detecting both events of (1) A new user being added and (2) a new friend being added.
I have tries iterating over the document changes data and restricting doc.document.data()["friends"] == nil. Why isn't this working/how can I properly add a restriction to only include when a new user is added?
func observeUsers(onSuccess: #escaping(UserCompletion)) {
Ref().firestoreUserRef.collection("users").addSnapshotListener { (querySnapshot, error) in
if error != nil {
print("error with observeUser snapshot")
return
}
querySnapshot?.documentChanges.forEach { doc in
//I want to detect that a new user was added, I do not want to detect if a friend was added
if (doc.type == .added) && doc.document.data()["friends"] == nil {
guard let dict = querySnapshot else { return }
for document in dict.documents {
var dictionary = [String : Any]()
dictionary = document.data()
if let user = User.transformUser(dict: dictionary) {
onSuccess(user)
}
}
}
}
}
}
The easiest way is starting from the data model to support the types of queries you want. In this case, when you create a new user (which I assume always has no friends), set the friends field explicitly to null. This will let you query for all new users:
Ref().firestoreUserRef.collection("users").whereField("friends", isEqualTo: NSNull()).addSnapshotListener ...
An assumption here is your transformUser process will update the document and replace null with either a list of friends of an empty array so that it no longer matches the query.
I am facing an issue in retrieving a data present in node
Dev->Regis->[userId("hjgsfgsdfghd8ydfsw3r")]->UserInfo->{userName:"", email:""}
I am trying the following query
ref.child(kChild).child(kRegistration).queryOrdered(byChild: kUserInfo).queryEqual(toValue: searchText).observeSingleEvent(of: .value) { (snapshot) in
if snapshot.exists() {
}
}
I also tries by making rules but it does make result
"Development": {
"Registration": {
"$user_id": {
"UserInfo": {
".indexOn": ["userName"],
".read": "auth.uid == $user_id"
}
}
}
}
database structure
and ref means Database.refrence()
Please help to sort out this problem.
Thanks.
Assuming searchText is the username value that you want to grab the object for. Firebase requires an orderBy call.
let searchText = //username you wish to fetch
let ref = db.ref('Development/Registration/${userId}/userInfo')
ref.orderByChild('userName').equalTo(searchText).once("value", function(snapshot) {
if(snapshot.exists()){
//whatever you want to do here
}
}
I have been trying to implement Chris’ answer here: Can I make Firebase use a username login process? for the Facebook login but I can’t seem to get my head around it.
So far I’ve tried to set conditions on the textField but as Firebase observer works asynchronously, the conditions to check if the username exists in the database won’t work.
let usernameString = usernameTextField.text
let uid = FIRAuth.auth()?.currentUser?.uid
ref.runTransactionBlock({ (currentData: FIRMutableData) -> FIRTransactionResult in
if var post = currentData.value as? [String : AnyObject], let uid = FIRAuth.auth()?.currentUser?.uid {
let usernamesDictionary = post["usernames"] as! NSDictionary
for (key, _) in usernamesDictionary {
if key as? String == usernameString {
print("username not available: \(key)")
}
else if usernameString == "" {
print("Uh oh! Looks like you haven't set a username yet.")
}
else if key as? String != usernameString {
print("username available: \(key)")
print("All set to go!")
let setValue: NSDictionary = [usernameString!: uid]
post["usernames"] = setValue
currentData.value = post
}
}
return FIRTransactionResult.successWithValue(currentData)
}
return FIRTransactionResult.successWithValue(currentData)
}
Then I tried creating /usernames/ node in the database and set up rules as:
{
"rules": {
"usernames": {
".read": "auth != null",
".write": "newData.val() === auth.uid && !data.exists()"
}
}
}
Now that won’t let me set any username to the database. I get confused in creating rules but my whole point is that I need a sign up flow with the username data that’s unique for each user in the database.
While trying every answer I found in related posts, what worked for me the easy way i.e. without making Firebase rules play a part in it or creating a separate usernames node in the database was to not put an if/else condition inside the Firebase observer but instead to use the exists() method of FIRDataSnapshot.
Now here’s the trick, while I did try only the exists() method with a simple observer but that did not help me. What I did was first query usernames in order, then match the username with queryEqualToValue to filter the query:
refUsers.queryOrderedByChild("username").queryEqualToValue(usernameString).observeSingleEventOfType(.Value , withBlock: {
snapshot in
if !snapshot.exists() {
if usernameString == "" {
self.signupErrorAlert("Uh oh!", message: "Looks like you haven't set a username yet.")
}
else {
// Update database with a unique username.
}
}
else {
self.signupErrorAlert("Uh oh!", message: "\(usernameString!) is not available. Try another username.")
}
}) { error in
print(error.localizedDescription)
}
}
This is the first time out of most of the answers here that worked for me. But for now, I don’t know if this would scale. Post your experiences and best practices. They’ll be appreciated.