SwiftUI + Firebase - Listener not listening for changes? - firebase

Question

I've set up a listener, but it doesn't seem to be changing according to changes in the data. The flow is the following:
If userCustomHabit is empty, user sees a button
When clicked, user can enter text in a TextField from a sheet to add to userCustomHabit (an array of strings)
Now that userCustomHabit is not empty, they should see something else
However, the problem I'm seeing is that userCustomHabits isn't updating in the view itself even though it is updating in the Firestore database.
Anyone know why this is? Included code below:
View
#ObservedObject var viewModel = RoutinesViewModel()
Group {
if self.viewModel.userCustomHabits.isEmpty {
Button(action: {
self.showCreateSheet.toggle()
}) {
Text("Create your own habits")
.font(Font.custom("Roboto-Regular", size: 20))
.frame(width: geometry.size.width * 88/100, height: 200)
.foregroundColor(.black)
.background(Color.init(UIColor.systemGray5))
.cornerRadius(40)
.overlay(
RoundedRectangle(cornerRadius: 40)
.stroke(style: StrokeStyle(lineWidth: 2, dash: [20]))
.foregroundColor(Color.init(UIColor.systemGray3))
)
}
}
else {
// Something else
}
}
.onAppear(perform: self.viewModel.newHabitsListener)
Sheet
VStack {
TextField("Enter text", text: $enteredText)
Button("Add Habit") {
self.viewModel.createNewHabits(newHabit: self.enteredText)
}
}
View Model
#Published var userCustomHabits = [String]()
func newHabitsListener() {
db.collection("users").document(currUser?.uid ?? "").addSnapshotListener { documentSnapshot, error in
guard let document = documentSnapshot else {
print("Error fetching document: \(error!)")
return
}
guard let data = document.data() else {
print("Document data was empty.")
return
}
DispatchQueue.main.async {
self.userCustomHabits = data["userCustomHabits"] as! [String]
}
}
}
func createNewHabits(newHabit: String) {
db.collection("users").document(currUser?.uid ?? "").updateData(["userCustomHabits": FieldValue.arrayUnion([newHabit])])
}

Answer 1

So I played around with your code a bit (since the code sample is incomplete, I had to make a few assumptions), and it seems like you might never have created the document you're writing to in the first place.
updateData only updates existing documents (see the documentation). To create a new document, use setData (see the documentation)
When changing your code form updateData to setData, the listener kicked in as expected.
However, it might be better to add a sub-collection customHabits to each user document. This way, adding new habits is as simple as adding a new document, which also makes querying a lot easier.