I'll explain myself better with some examples now.

Basically I have a working login and registration process and whenever one user registers, he gets added to the DB on Firebase. Now, when he registers I get:

• Name
• Surname
• email

and they all are added to the user information.

My Database has this structure:

Now, my task is to get the "nome" value (name in italian...) to print out , but how in the hell do I do this? The placeholder has to be substituted with the data from the DB and if the user changes it and presses the button it should modify the entry in the DB.

I read all the documentation and feel very stupid having not yet solved this problem.

Please help me!

This is all the code I have right now:

    let db = Firestore.firestore()
    
    var userID = Auth.auth().currentUser?.uid
        userID = String(userID!)
    
    let utenti = db.collection("utenti").document()
    let nomeUtente = utenti.getDocument("nome")

Code of the button I use to register my users to the DB:

{
    
    // Verifico nome e cognome
    
    let erroreNome_Cognome = validazioneCampi()
    
    if erroreNome_Cognome != nil {
        // In caso non fossero compilati i campi do errore.
        mostraErrore(erroreNome_Cognome!)
    } else if let email = emailTextField.text, let password = passwordTextField.text {   // Uso binding opzionale per evitare errori con i valori
            Auth.auth().createUser(withEmail: email, password: password) { authResult, error in
                if let e = error { // Uso di nuovo optional binding per errore
                    self.labelErrore.text = e.localizedDescription
                } else {
                    // Pulisco i dati per il DB - Uso .trimmingCharacters per rimuovere, usando whitespacesAndNewlines, spazi e punti a capo
                    let nome = self.nomeTextField.text!.trimmingCharacters(in: .whitespacesAndNewlines)
                    let cognome = self.cognomeTextField.text!.trimmingCharacters(in: .whitespacesAndNewlines)
                    
                    // Quello che ho appena fatto, è possibile anche per la verifica dei dati svolta prima con erroreNome_Cognome. Infatti, senza di esso non potrei spacchettare il
                    // dato con "!".
                    
                    // Qui creo l'utente nel database
                    let db = Firestore.firestore()
                    
                    db.collection("utenti").addDocument(data: ["nome":nome, "cognome":cognome, "email": email, "uid": authResult!.user.uid]) { (erroreNome_Cognome) in
                        
                        if erroreNome_Cognome != nil {
                            // Mostra errore
                            self.mostraErrore("I dati utenti non sono validi per il database")
                        }
                    }
                    
                    // Naviga alla pagina successiva qui
                    self.performSegue(withIdentifier: "registratiAWelcome", sender:self)
                }
            }
        }
    


}

CodePudding user response：

Ok, I can see that you already have your Firebase into your project.

Let's review your code:

When you are doing:

db.collection("utenti").document()

you are telling Firestore that you want to create a new document, and to create a reference to the future document. So nothing to do with this, if you want more information about this method: https://firebase.google.com/docs/firestore/manage-data/add-data#add_a_document

then when you are doing

utenti.getDocument("nome")

nome is a field of your document, it's not a document, and this document "nome" doesn't exists. If you want to query a specific document, you should do for example:

let db = Firestore.firestore()
let docRef = db.collection("utenti").document("cwmG6g0xgVe6txYSfKqm")
docRef.getDocument { (document, error) in
    if let document = document, document.exists {
        let dataDescription = document.data().map(String.init(describing:)) ?? "nil"
        print("Document data: \(dataDescription)")
    } else {
        print("Document does not exist")
    }
}

More info about this here: https://firebase.google.com/docs/firestore/query-data/get-data#get_a_document

Now with the current structure that you have on your database, what you would like to do base on you user uid is a query to all the documents, then this documents will have the fields like "nome"

let db = Firestore.firestore()
let userID = Auth.auth().currentUser!.uid
db.collection("utenti").whereField("uid", isEqualTo: userID).getDocuments { querySnapshot, error in
    if let error = error {
       print(error)
    } else {
        for document in querySnapshot!.documents {
            print("\(document.documentID) => \(document.data())")
        }
    }
}

you have more information https://firebase.google.com/docs/firestore/query-data/get-data#get_multiple_documents_from_a_collection and https://firebase.google.com/docs/firestore/query-data/get-data#get_all_documents_in_a_collection

Hope this helps, I know you will have more questions, but play debugging the information and trying around to get a grip of Firestore SDK