SwiftUI - Firebase: Value of type 'String' has no member 'documentID' - swift

Question

When I try to get user data from firebase I have an error. The error message is:
Value of type 'String' has no member 'documentID'
The line with the error is the line fetchUser(uid: uid.documentID) { (user) in:
let title = doc.document.data()["title"] as? String ?? "No Title"
let time = doc.document.data()["time"] as? Timestamp ?? Timestamp(date: Date())
let pic = doc.document.data()["url"] as? String ?? "No URL"
let uid = doc.document.data()["uid"] as? String ?? ""
// getting user Data...
fetchUser(uid: uid.documentID) { (user) in
And this is my FetchUser model:
// Global Refernce
let ref = Firestore.firestore()
func fetchUser(uid: String,completion: #escaping (UserModel) -> ()){
ref.collection("Users").document(uid).getDocument { (doc, err) in
guard let user = doc else{return}
let username = user.data()?["username"] as? String ?? "No Username"
let pic = user.data()?["imageurl"] as? String ?? "No image URL"
let bio = user.data()?["bio"] as? String ?? "No bio"
let uid = user.data()?["uid"] as? String ?? ""
DispatchQueue.main.async {
completion(UserModel(username: username, pic: pic, bio: bio, uid: uid))
}
}
}
Below is code to that checks the users uid. On the line that starts "ref.collection..." the error "Cannot find 'uid' in scope" is thrown.
func checkUser(){
let ref = Firestore.firestore()
if let currentUser = Auth.auth().currentUser {
let uid = currentUser.uid
} else {
print("No Authenticated User")
return
}
ref.collection("Users").whereField("uid", isEqualTo: uid).getDocuments { (snap, err) in
if err != nil{
// No Documents..
// No User Found...
self.registerUser.toggle()
self.isLoading = false
return
}
if snap!.documents.isEmpty{
self.registerUser.toggle()
self.isLoading = false
return
}
self.log_Status = true
}
}

Answer 1

Let me take the first part of your code to show where the issue is. Note how much easier it is to read when properly formatted
func checkUser() {
let ref = Firestore.firestore()
if let currentUser = Auth.auth().currentUser {
//NOTE! Note that this area is encapsulated with brackets { and }
//That means it's is own 'space' and anything defined in this area
//only exists in this area
let uid = currentUser.uid //<- uid only exists here
} else {
print("No Authenticated User")
return
}
//uid no longer exists and cannot be referenced
// e.g. it's not in 'scope' at this point
ref.collection("Users").whereField("uid", isEqualTo: uid)
However, if you look at where the let ref = Firestore line is located, it's at the top level within the checkUser function and will exist throughout the function.
There are many way to do this; here's one using a guard statement
func checkUser() {
let ref = Firestore.firestore()
guard let currentUser = Auth.auth().currentUser else {
print("no user!")
return
}
// currentUser flows through to here because it was created with
// a guard statement, so now we know it's populated and can
// get the uid property value from it
let uid = currentUser.uid
ref.collection("Users").whereField("uid", isEqualTo: uid)
guard is pretty neat in that it not only allows you to instantiate a var while a the same time as protecting your code from a nil situation, it also allows the var to flow through to the code following the guard.

Answer 2

I'm writting this answer as a community wiki, since the issue was resolved from the comments section, in order to provide a proper response to the issue reported.
The error came while trying to get the uid as fetchUser(uid: uid.documentID), instead the correct way is by doing fetchUser(uid: uid)
Then an error mentioning Document path cannot be empty appeared, which was mainly due to the fact that no entries with were loaded, the best way to avoid this is to load documents on the consulted path without nil values