How to change document in Firestore without String error?

Question

In my app a first time user creates a username which I save in Firestore as a document and set it as displayName (username = name of document = displayName). In the app the user has the option to change his username by typing a new one in an EditText. The result should be that the data which is stored under his current username moves to a new document which has the new username. So first I check if the new username is already in use by someone else, if not I create a new document which name is the new username. Now I get the current displayName (which is the current username) as a string and the input of the EditText as a string (new username). I Implemented a method to move documents from here: How to move a document in Cloud Firestore?

But when I call the method like this moveFirestoreDocument(usernameInput, oldUsername ); I get:

moveFirestoreDocument cannot be applied to (String, String)

How can I resolve this problem? Can I change the moveFirestoreDocument method so it can also takes Strings?

Here is the method:

public void moveFirestoreDocument(DocumentReference fromPath, final DocumentReference toPath) {
        fromPath.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
            @Override
            public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                if (task.isSuccessful()) {
                    DocumentSnapshot document = task.getResult();
                    if (document != null) {
                        toPath.set(document.getData())
                                .addOnSuccessListener(new OnSuccessListener<Void>() {
                                    @Override
                                    public void onSuccess(Void aVoid) {
                                        Log.d(TAG, "DocumentSnapshot successfully written!");
                                        fromPath.delete()
                                                .addOnSuccessListener(new OnSuccessListener<Void>() {
                                                    @Override
                                                    public void onSuccess(Void aVoid) {
                                                        Log.d(TAG, "DocumentSnapshot successfully deleted!");
                                                    }
                                                })
                                                .addOnFailureListener(new OnFailureListener() {
                                                    @Override
                                                    public void onFailure(@NonNull Exception e) {
                                                        Log.w(TAG, "Error deleting document", e);
                                                    }
                                                });
                                    }
                                })
                                .addOnFailureListener(new OnFailureListener() {
                                    @Override
                                    public void onFailure(@NonNull Exception e) {
                                        Log.w(TAG, "Error writing document", e);
                                    }
                                });
                    } else {
                        Log.d(TAG, "No such document");
                    }
                } else {
                    Log.d(TAG, "get failed with ", task.getException());
                }
            }
        });
    }

Why aren't you just passing it document references as it's declared? — Doug Stevenson, Oct 15 '19 at 14:15
What do you mean by that? I am new to Firestore so I don't know how to do this — Kaiser, Oct 15 '19 at 14:26

score 3 · Accepted Answer · answered Oct 16 '19 at 07:48

You get the following error:

I get "moveFirestoreDocument cannot be applied to (String, String)

Because you are trying to pass to the moveFirestoreDocument() method two arguments of type String and not of type DocumentReference. In order to be able to move a document, both fromPath and toPath must be of type DocumentReference so you can call set() on toPath and get() and delete() on fromPath.

Can I change the moveFirestoreDocument method so it can also takes Strings?

There is no need to change the method, you can simply pass the correct arguments when you call it. According to the details that you have provided in the question, I understand that you have a schema that is similar to this:

Firestore-root
   |
   --- users (collection)
         |
         --- John (document)
              |
              --- //User details

To rename the document call the method using:

FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
CollectionReference usersRef = rootRef.collection("users");
DocumentReference oldUsernameRef = usersRef.document(oldUsername);
DocumentReference usernameInputRef = usersRef.document(usernameInput);
moveFirestoreDocument(oldUsernameRef, usernameInputRef);

How to change document in Firestore without String error?

1 Answers1