java - 检查 Cloud Firestore 中是否已存在用户 Google 登录凭据

Question

我在 Google 登录中遇到问题，每当我使用 Google 登录时，我都会将凭据设置为添加到数据库中(例如:姓名和电子邮件)，但是所有问题都正常，除了现在每个当我使用相同的谷歌帐户登录时，它会再次添加到数据库中(一遍又一遍地添加相同的凭据)，所以我想检查数据库中是否已存在谷歌登录凭据，无需重新添加凭据.

这里是 onCreate 中的 Google 登录代码:

private FirebaseAuth firebaseAuth;
private FirebaseFirestore firebaseFirestore;
private GoogleSignInClient mGoogleSignInClient;
private static final int RC_SIGN_IN = 100;


googleImageBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            progresBarDim.setVisibility(View.VISIBLE);
            signIn();
        }
    });

// TODO : Firebase Authentication
    firebaseAuth = FirebaseAuth.getInstance();
    firebaseFirestore = FirebaseFirestore.getInstance();
    googleRequest();

这是 google 登录的方法:

private void googleRequest(){
    // Configure Google Sign In
    GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestIdToken(getString(R.string.default_web_client_id))
            .requestEmail()
            .build();

    // Build a GoogleSignInClient with the options specified by gso.
    mGoogleSignInClient = GoogleSignIn.getClient(this, gso);
}

private void signIn() {
    Intent signInIntent = mGoogleSignInClient.getSignInIntent();
    startActivityForResult(signInIntent, RC_SIGN_IN);
}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);


    // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
    if (requestCode == RC_SIGN_IN) {
        Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
        try {
            // Google Sign In was successful, authenticate with Firebase
            GoogleSignInAccount account = task.getResult(ApiException.class);
            firebaseAuthWithGoogle(account);
        } catch (ApiException e) {
            progresBarDim.setVisibility(View.GONE);
            // Google Sign In failed, update UI appropriately
            Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show();
            // ...
        }
    }
}

private void firebaseAuthWithGoogle(GoogleSignInAccount acct) {


    AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
    firebaseAuth.signInWithCredential(credential)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (task.isSuccessful()) {
                        GoogleSignInAccount signInAccount = GoogleSignIn.getLastSignedInAccount(LoginActivity.this);
                        final String name = signInAccount.getDisplayName().trim();
                        final String email =signInAccount.getEmail().trim();

                        Map<Object, String> userdata = new HashMap<>();
                        userdata.put("Nom et prénom", name);
                        userdata.put("Address émail", email);

                        firebaseFirestore.collection("USERS")
                                .add(userdata);

                        // Sign in success, update UI with the signed-in user's information
                        FirebaseUser user = firebaseAuth.getCurrentUser();
                        Intent intent = new Intent(LoginActivity.this, ProfileActivity.class);
                        startActivity(intent);

                    } else {
                        progresBarDim.setVisibility(View.GONE);
                        // If sign in fails, display a message to the user.
                        Toast.makeText(LoginActivity.this, "sorry auth failed!", Toast.LENGTH_SHORT).show();
                    }
                    progresBarDim.setVisibility(View.GONE);

                    // ...
                }
            });
}

Answer 1

it gets added again in Realtime database( same credentials over and over)

发生这种情况是因为您一遍又一遍地添加数据。负责此行为的是以下代码行:

firebaseFirestore.collection("USERS")
                            .add(userdata);

当您使用add(Object data)时:

Adds a new document to this collection with the specified data, assigning it a document ID automatically.

因此，每次调用上述代码行时，都会创建一个新文档。要解决此问题，您应该将数据添加到特定位置，例如，在以下引用处:

Firestore-root
  |
  --- users (collection)
       |
       --- uid  (document)
            |
            --- Nom et prénom: "User Name"
            |
            --- Address émail: "User Email"

您可以使用以下代码行从 FirebaseUser 对象获取 uid:

String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();

现在，要写入数据，请使用以下代码:

firebaseFirestore.collection("USERS").document(uid)
                            .set(userdata);

但我没有使用 add()，而是在 DocumentReference 对象上使用 set()。为了避免每次用户登录 Google 时都写入数据，您需要检查该用户是否已经存在，这可以使用我在以下帖子中的回答来完成:

• Firestore query - checking if username already exists

但是您应该检查uid，而不是检查用户名。

附注您的代码表明您在设置标记时使用的是 Cloud Firestore，而不是Firebase Realtime Database。