How to extract individual values from Firestore getDocument request using Swift - swift

Question

let db = Firestore.firestore()
let docRef = db.collection("users").document(result!.user.uid)
docRef.getDocument { (document, error) in
if let document = document, document.exists {
let dataDescription = document.data().map(String.init(describing:)) ?? "nil"
print("Document data: \(dataDescription)")
print()
} else {
print("Document does not exist")
}
}
print("Document data: \(dataDescription)") outputs the following:
Document data: ["uid": LjqBXo41qMStt89ysQ4I9hxla2h1, "firstname": Tim, "lastname": Dorsemagen]
How can I extract each value such as the uid, the firstname and the lastname from dataDescription?

Answer 1

There are several ways to accomplish this. One of the most easily understood would be to break the string down in sections. Assuming you only want the values rather than their keys:
let values = dataDescription
.dropFirst()
.dropLast()
.components(separatedBy: ",")
.map{$0.components(separatedBy: ":")}
.map{$0.last!.trimmingCharacters(in: .whitespaces)}
print(values) //["LjqBXo41qMStt89ysQ4I9hxla2h1", "Tim", "Dorsemagen"]

Answer 2

Firestore has everything needed to easily get components of a document. Here's an asynchronous example of reading a users name from a document and returning it
func getUserAsync() async -> String{
let usersCollection = self.db.collection("users") //self.db is my Firestore
let thisUserDoc = usersCollection.document("uid_0")
let document = try! await thisUserDoc.getDocument()
let name = document.get("name") as? String ?? "No Name"
return name
}
if you want to use Codable (advised! See Mapping Firestore Data), this works for printing the name (can also be combined with the above solution)
func readUser() {
let usersCollection = self.db.collection("users") //self.db is my Firestore
let thisUserDoc = usersCollection.document("uid_0")
thisUserDoc.getDocument(completion: { document, error in
if let doc = document {
let user = try! doc.data(as: UserCodable.self)
print(user.name) //assume the UserCodable object has a name property
}
}
}
or just a regular old read of a document and print the name
func readUser() {
let usersCollection = self.db.collection("users") //self.db is my Firestore
let thisUserDoc = usersCollection.document("uid_0")
thisUserDoc.getDocument(completion: { document, error in
let name = document?.get("name") as? String ?? "No Name"
print(name)
})
}
*note: no error checking and I am force unwrapping options. Don't do that.