I have the following query;
fileprivate func observeQuery() {
guard let query = query else { return }
stopObserving()
listener = query.addSnapshotListener({ [unowned self] (snapshot, error) in
guard let snapshot = snapshot else { return }
let models = snapshot.documents.map({ (document) -> Post in
if let model = Post(dictionary: document.data()) {
return model
} else {
print(error as Any)
}
}) //here
self.posts = models
self.documents = snapshot.documents
})
}
I am getting "Missing return in a closure expected to return 'Post'" mentioned as "//here" in the code. I have return model which is of type Post and I cannot access model after the closure. I have used the GitHub files here;
Firestore GitHub iOS Quickstart
This error doesn't make sense to me can someone please shed some light on the matter?
Many thanks as always.
Your issue is that not all code branches return inside the closure of your map statement. You should change map to flatMap, this way you can also get rid of the if statement by simply returning the failable initializer's result inside your closure, since flatMap will filter out all nil return values.
let models = snapshot.documents.flatMap({ document in Post(dictionary: document.data())})
Related
I'm trying to build an iOS app in SwiftUI where users can find a "Post" near to their current location. I have a sub collection called Posts with a geohash. Somewhat annoyingly this library by google has been archived https://github.com/firebase/geofire-objc for no reason. Instead I had to use this library https://github.com/emilioschepis/swift-geohash.
I find all the neighboring geohashes around the current user and then run a query against firstore for each geohash starting with geohash and ending with geohash + '~'.
Here is the function I wrote:
// import https://github.com/emilioschepis/swift-geohash
class FirestorePosts: ObservableObject {
#Published var items = [FirestorePost]() // Reference to our Model
func geoPointQuery(tag:String){
do {
let db = Firestore.firestore().collection("tags")
let docRef = db.document(tag).collection("posts")
// users current location is "gcpu"
let neighbors = try Geohash.neighbors(of: "gcpu", includingCenter: true)
let queries = neighbors.map { bound -> Query in
let end = "\(bound)~"
return docRef
.order(by: "geohash")
.start(at: [bound])
.end(at: [end])
}
func getDocumentsCompletion(snapshot: QuerySnapshot?, error: Error?) -> () {
guard let documents = snapshot?.documents else {
print("Unable to fetch snapshot data. \(String(describing: error))")
return
}
self.items += documents.compactMap { queryDocumentSnapshot -> FirestorePost? in
return try? queryDocumentSnapshot.data(as: FirestorePost.self)
}
}
for query in queries {
print("ran geo query")
query.getDocuments(completion: getDocumentsCompletion)
}
}
catch{
print(error.localizedDescription)
}
}
}
So far the query works and returns items as expected. However, the results are not updated in realtime when there is a change in Firestore.
How could I make this query update results in realtime? I tried adding query.addSnapshotListener instead but it doesn't like "completion:" parameter
How can I ensure that all the queries are finished before returning the results
You're calling query.getDocuments, which gets data once. If you want to also get updates to that data, you should use addSnapshotListener which listens for updates after getting the initial docs.
To ensure all queries are finished, you could keep a simple counter that you increase each time your addSnapshotListener callback is invoked. When the counter is equal to the number of queries, all of them have gotten a response from the server. That's exactly what the geofire-* libraries for Realtime Database do for their onReady event.
I refactored to this and it seems to work and updates in realtime. I didn't need to use a counter since Im appending the documents to self.items (not sure if thats correct though).
...
for query in queries {
query.addSnapshotListener { (querySnapshot, error) in
guard let documents = querySnapshot?.documents else {
print("No documents")
return
}
self.items += documents.compactMap { queryDocumentSnapshot -> FirestorePost? in
return try? queryDocumentSnapshot.data(as: FirestorePost.self)
}
}
}
This is the first time I am using a Firestore Query and I'm struggling to parse the data. I normally use the same setup when I get documents (which works), but when I attach it to a query it does not work.
I am trying to query the database for the shop most visited, so I can later set it as favourite.
My Code:
func findFavouriteShop(completed: #escaping ([String]) -> Void)
{
// Variables
let dispatch = DispatchGroup()
var dummyDetails = [String]()
// References
let db = Firestore.firestore()
let userID = Auth.auth().currentUser?.uid
let groupCollectionRef = String("visits-" + userID! )
// Query the database for the document with the most counts
dispatch.enter()
db.collectionGroup(groupCollectionRef).order(by: "count", descending: true).limit(to: 1).getDocuments { (snapshot, error) in
if let err = error {
debugPrint("Error fetching documents: \(err)")
}
else {
print(snapshot)
guard let snap = snapshot else {return}
for document in snap.documents {
let data = document.data()
// Start Assignments
let shopName = data["shopName"] as? String
let count = data["count"] as? String
// Append the dummy array
dummyDetails.append(shopName!)
dummyDetails.append(count!)
}
dispatch.leave()
}
dispatch.notify(queue: .main, execute: {
print("USER number of documents appended: \(dummyDetails.count)")
completed(dummyDetails)}
)
}
Using Print statements it seems as if the guard statement kicks the function out. The processor does not reach the for-loop to do the assignments. When I print the snapshot it returns an empty array.
I am sure I have used the wrong notation, but I'm just not sure where.
There's a lot to comment on, such as your choice of collection groups over collections (maybe that's what you need), why you limit the results to one document but feel the need to query a collection, the naming of your collections (seems odd), the query to get multiple shops but creating a function that only returns a single shop, using a string for a count property that should probably be an integer, and using a string array to return multiple components of a single shop instead of using a custom type.
That said, I think this should get you in the right direction. I've created a custom type to show you how I'd start this process but there's a lot more work to be done to get this where you need it to be. But this is a good starting point. Also, there was no need for a dispatch group since you weren't doing any additional async work in the document parsing.
class Shop {
let name: String // constant
var count: Int // variable
init(name: String, count: Int) {
self.name = name
self.count = count
}
}
func findFavouriteShops(completion: #escaping (_ shops: [Shop]?) -> Void) {
guard let userID = Auth.auth().currentUser?.uid else {
completion(nil)
return
}
var temp = [Shop]()
Firestore.firestore().collection("visits-\(userID)").order(by: "count", descending: true).limit(to: 1).getDocuments { (snapshot, error) in
guard let snapshot = snapshot else {
if let error = error {
print(error)
}
completion(nil)
return
}
for doc in snapshot.documents {
if let name = doc.get("shopName") as? String,
let count = doc.get("count") as? String {
let shop = Shop(name: name, count: count)
temp.append(Shop)
}
}
completion(temp)
}
}
You can return a Result type in this completion handler but for this example I opted for an optional array of Shop types (just to demonstrate flexibility). If the method returns nil then there was an error, otherwise there are either shops in the array or there aren't. I also don't know if you're looking for a single shop or multiple shops because in some of your code it appeared you wanted one and in other parts of your code it appeared you wanted multiple.
findFavouriteShops { (shops) in
if let shops = shops {
if shops.isEmpty {
print("no error but no shops found")
} else {
print("shops found")
}
} else {
print("error")
}
}
I am looking to add all my "usernames" into a dictionary. I am having some trouble doing this. I am sure it's very obvious, but I am very new to coding.
I am stuck at, right now and can't seem to find a clear answer anywhere:
func fetchUser() {
let db = Firestore.firestore()
let usernameSearch = db.collection("users")
usernameSearch.getDocuments { (snapshot, error) in
if error != nil {
print("Error obtaining usernames")
} else {
for field in snapshot!.documents {
let field = field.get("username")
print(field!)
}
}
}
}
I would really appreciate it if somebody could help me out. I am sure it's very obvious, or I'm just doing it totally wrong.
First, get into the habit of safely unwrapping over force unwrapping. And choose more accurate names for your objects (i.e. usersCollection over usernameSearch). However, in this case, there's no need to instantiate individual properties for the database and the collection since they're not being used anywhere else but here (so be efficient and omit them).
var usersDictionary = [String: [String]]()
func fetchUser() {
Firestore.firestore().collection("users").getDocuments { (snapshot, error) in
if let snapshot = snapshot { // unwrap the snapshot safely
var usernames = [String]()
for doc in snapshot.documents {
if let username = doc.get("username") as? String {
usernames.append(username)
}
}
usersDictionary["usernames"] = usernames
} else {
if let error = error {
print(error)
}
}
}
}
Or if you actually meant an array of users:
var usersArray = [String]()
func fetchUser() {
Firestore.firestore().collection("users").getDocuments { (snapshot, error) in
if let snapshot = snapshot { // don't force unwrap with !
for doc in snapshot.documents {
if let username = doc.get("username") as? String {
usersArray.append(username)
}
}
} else {
if let error = error {
print(error)
}
}
}
}
I'm assuming that what you're looking for is an Array, not a Dictionary. I'll also assume that you are indeed getting the correct value that you'd expect out of field.get("username"), e.g. a string such as "Bob." Therefore, what you are trying to do is map the list of document objects to a list of strings.
If you scroll to the Topics section of the Array documentation from Apple, you can find some of the operations they provide for arrays such as snapshot!.documents.
One of those operations is actually map, and its description is:
Returns an array containing the results of mapping the given closure over the sequence’s elements.
https://developer.apple.com/documentation/swift/array/3017522-map
In other words, you provide a transformation to perform for each instance of a document belonging to the snapshot!.documents Array and get back a new Array containing the resultant values of that transformation.
In this case I will use a more specific operation; compactMap. We have to try and cast the returned value from Any to String. If that does not succeed, it will return nil, and we'll want to filter that out. I expect it to be an unlikely case due to the type requirements made by the Firebase Console, but it's good to be aware of it. Here is the example:
func fetchUsernames(from usernameCollection: String, completion: #escaping ([String]) -> Void) {
let db = Firestore.firestore()
let collection = db.collection(usernameCollection)
collection.getDocuments { snapshot, error in
guard error != nil,
let usernames = snapshot?.documents.compactMap { $0.get("username") as? String }
else { return print("Error obtaining usernames") }
completion(usernames)
}
}
The key line here being let usernames = snapshot?.documents.compactMap { $0.get("username") }. We are passing the map function a closure. This closure is passed an argument itself; each value from the snapshot?.documents array. You may refer to this passed in value with $0.
All that I'm trying to do is to check whether the value for a 'key' exists in a Firestore collection as a document and return a Bool.
But I can't seem to return anything within the getDocument,
so I thought that I should then keep a results var and update the results var but the changes I make to results don't stick and it stays default false.
How do I simplify this whole mess?
func checkIfValid(db: Firestore, key: String) -> Bool {
let resolve = db.collection("keys").document(key)
var results = false
resolve.getDocument{ (document, error) in
if let document = document, document.exists {
var results = true
} else { results = false }
}
print(results)
return results
}
Reading the firebase docs, they have a small warning below the sample code.
Note: If there is no document at the location referenced by docRef,
the resulting document will be empty and calling exists on it will
return false.
However, you need to add a completion handler to the function given you're working with network requests. Swift will return the result variable given you specified it; ignoring any response from the getDocuments handler.
I changed the function to fix your mess.
func checkIfValid(db: Firestore, key: String, completion: #escaping(Bool) -> ()) {
let docRef = db.collection("user").document(key)
docRef.getDocument { (document, error) in
if let document = document, document.exists {
print("document exists.")
completion(true)
} else {
print("document does not exists.")
completion(false)
}
}
}
And to get the response, just use this.
checkIfValid(db: db, key: "", completion: {success in
print(success)
})
I am trying to read the value of a Firestore document. I have tried doing it two different ways, but each fails.
In the first one, an error is thrown on the return line: Unexpected non-void return value in void function. I found out why this happened, and so, I implemented the second way.
import UIKit
import Firestore
func readAvailableLists(forUser user: String) -> [String] {
let db = Firestore.firestore()
db.collection("userslist").document(user).getDocument { (document, err) in
if let document = document, document.exists {
return UserInformationDocument(dictionary: document.data()!)?.lists!
} else {
print("Document does not exist")
}
}
}
In the second method, I assign the UserInformationDocument(dictionary: document.data()!)?.lists! to a variable and return that variable at the end of the function (see code below). However, when I do this, it the function returns an empty array. What surprises me is that the print return the correct value, but after long after the function has executed the return statement. Is it because it is an async demand? And if so, how should I fix this?
import UIKit
import Firestore
func readAvailableLists(forUser user: String) -> [String] {
let db = Firestore.firestore()
var firestoreUserDocument: [String] = []
db.collection("userslist").document(user).getDocument { (document, err) in
if let document = document, document.exists {
firestoreUserDocument = (UserInformationDocument(dictionary: document.data()!)?.lists!)!
print((UserInformationDocument(dictionary: document.data()!)?.lists!)!)
} else {
print("Document does not exist")
}
}
return firestoreUserDocument
}
The Firebase call is an asynchronous function. It takes extra time to execute because it's talking to a server (as you've noted) - as a result, the completion block (the block that defines document and err in your example) happens at a different time, outside of the rest of the body of the function. This means you can't return a value from inside it, but you can pass another closure through to it, to execute later. This is called a completion block.
func readAvailableLists(forUser user: String, completion: #escaping ([String]?, Error?) -> Void) -> [String] {
let db = Firestore.firestore()
db.collection("userslist").document(user).getDocument { (document, err) in
if let document = document, document.exists {
// We got a document from Firebase. It'd be better to
// handle the initialization gracefully and report an Error
// instead of force unwrapping with !
let strings = (UserInformationDocument(dictionary: document.data()!)?.lists!)!
completion(strings, nil)
} else if let error = error {
// Firebase error ie no internet
completion(nil, error)
}
else {
// No error but no document found either
completion(nil, nil)
}
}
}
You could then call this function elsewhere in your code as so:
readAvailableLists(forUser: "MyUser", completion: { strings, error in
if let strings = strings {
// do stuff with your strings
}
else if let error = error {
// you got an error
}
})