使用 JavaScript 將多個驗證提供者連結至帳戶

您可以將驗證服務供應商憑證連結至現有使用者帳戶，讓使用者透過多個驗證服務供應商登入應用程式。無論使用者登入時使用哪個驗證服務供應器，系統都會使用相同的 Firebase 使用者 ID 識別使用者。舉例來說，使用者可以透過密碼登入，日後再連結 Google 帳戶，並使用任一方法登入。或者，匿名使用者可以連結 Facebook 帳戶，之後再使用 Facebook 帳戶登入，繼續使用您的應用程式。

事前準備

為應用程式新增對兩個以上驗證服務供應商的支援 (可能包括匿名驗證)。

如要將 Google 或 Facebook 等授權提供者的憑證連結至現有使用者帳戶，請按照下列步驟操作：

  1. 使用任何驗證提供者或方法登入使用者。
  2. 取得與您要連結至使用者帳戶的供應商相對應的 AuthProvider 物件。例如：

    Web

    import { GoogleAuthProvider, FacebookAuthProvider, TwitterAuthProvider, GithubAuthProvider } from "firebase/auth";

const googleProvider = new GoogleAuthProvider();
const facebookProvider = new FacebookAuthProvider();
const twitterProvider = new TwitterAuthProvider();
const githubProvider = new GithubAuthProvider();
    auth_get_providers.js

    Web

    var googleProvider = new firebase.auth.GoogleAuthProvider();
var facebookProvider = new firebase.auth.FacebookAuthProvider();
var twitterProvider = new firebase.auth.TwitterAuthProvider();
var githubProvider = new firebase.auth.GithubAuthProvider();
    link-multiple-accounts.js
  3. 提示使用者登入要連結的服務供應商。您可以開啟彈出式視窗，或重新導向至提供者的登入頁面，以便提示使用者登入。在行動裝置上，建議使用重新導向方法。
    • 如要透過彈出式視窗登入，請呼叫 linkWithPopup：

      Web

      import { getAuth, linkWithPopup, GoogleAuthProvider } from "firebase/auth";
const provider = new GoogleAuthProvider();

const auth = getAuth();
linkWithPopup(auth.currentUser, provider).then((result) => {
  // Accounts successfully linked.
  const credential = GoogleAuthProvider.credentialFromResult(result);
  const user = result.user;
  // ...
}).catch((error) => {
  // Handle Errors here.
  // ...
});
      auth_link_with_popup.js

      Web

      auth.currentUser.linkWithPopup(provider).then((result) => {
  // Accounts successfully linked.
  var credential = result.credential;
  var user = result.user;
  // ...
}).catch((error) => {
  // Handle Errors here.
  // ...
});
      link-multiple-accounts.js
    • 如要透過重新導向供應商的登入頁面登入，請呼叫 linkWithRedirect： 使用 `linkWithRedirect` 時，請遵循最佳做法。

      Web

      import { getAuth, linkWithRedirect, GoogleAuthProvider } from "firebase/auth";
const provider = new GoogleAuthProvider();

const auth = getAuth();
linkWithRedirect(auth.currentUser, provider)
  .then(/* ... */)
  .catch(/* ... */);
      auth_link_with_redirect.js

      Web

      auth.currentUser.linkWithRedirect(provider)
  .then(/* ... */)
  .catch(/* ... */);
      link-multiple-accounts.js
      使用者登入後，系統會將他們重新導向至您的網頁。接著，您可以在頁面載入時呼叫 getRedirectResult，藉此擷取登入結果：

      Web

      import { getRedirectResult } from "firebase/auth";
getRedirectResult(auth).then((result) => {
  const credential = GoogleAuthProvider.credentialFromResult(result);
  if (credential) {
    // Accounts successfully linked.
    const user = result.user;
    // ...
  }
}).catch((error) => {
  // Handle Errors here.
  // ...
});
      auth_get_redirect_result.js

      Web

      auth.getRedirectResult().then((result) => {
  if (result.credential) {
    // Accounts successfully linked.
    var credential = result.credential;
    var user = result.user;
    // ...
  }
}).catch((error) => {
  // Handle Errors here.
  // ...
});
      link-multiple-accounts.js
    如果使用者成功登入，供應商的使用者帳戶就會連結至 Firebase 專案中的使用者帳戶。

    如果憑證已連結至其他使用者帳戶，帳戶連結作業就會失敗。在這種情況下，您必須視應用程式而定，適當處理帳戶和相關資料的合併作業：

    Web

    import { getAuth, signInWithCredential, linkWithCredential, OAuthProvider } from "firebase/auth";

// The implementation of how you store your user data depends on your application
const repo = new MyUserDataRepo();

// Get reference to the currently signed-in user
const auth = getAuth();
const prevUser = auth.currentUser;

// Get the data which you will want to merge. This should be done now
// while the app is still signed in as this user.
const prevUserData = repo.get(prevUser);

// Delete the user's data now, we will restore it if the merge fails
repo.delete(prevUser);

// Sign in user with the account you want to link to
signInWithCredential(auth, newCredential).then((result) => {
  console.log("Sign In Success", result);
  const currentUser = result.user;
  const currentUserData = repo.get(currentUser);

  // Merge prevUser and currentUser data stored in Firebase.
  // Note: How you handle this is specific to your application
  const mergedData = repo.merge(prevUserData, currentUserData);

  const credential = OAuthProvider.credentialFromResult(result);
  return linkWithCredential(prevUser, credential)
    .then((linkResult) => {
      // Sign in with the newly linked credential
      const linkCredential = OAuthProvider.credentialFromResult(linkResult);
      return signInWithCredential(auth, linkCredential);
    })
    .then((signInResult) => {
      // Save the merged data to the new user
      repo.set(signInResult.user, mergedData);
    });
}).catch((error) => {
  // If there are errors we want to undo the data merge/deletion
  console.log("Sign In Error", error);
  repo.set(prevUser, prevUserData);
});
    auth_merge_accounts.js

    Web

    // The implementation of how you store your user data depends on your application
var repo = new MyUserDataRepo();

// Get reference to the currently signed-in user
var prevUser = auth.currentUser;

// Get the data which you will want to merge. This should be done now
// while the app is still signed in as this user.
var prevUserData = repo.get(prevUser);

// Delete the user's data now, we will restore it if the merge fails
repo.delete(prevUser);

// Sign in user with the account you want to link to
auth.signInWithCredential(newCredential).then((result) => {
  console.log("Sign In Success", result);
  var currentUser = result.user;
  var currentUserData = repo.get(currentUser);

  // Merge prevUser and currentUser data stored in Firebase.
  // Note: How you handle this is specific to your application
  var mergedData = repo.merge(prevUserData, currentUserData);

  return prevUser.linkWithCredential(result.credential)
    .then((linkResult) => {
      // Sign in with the newly linked credential
      return auth.signInWithCredential(linkResult.credential);
    })
    .then((signInResult) => {
      // Save the merged data to the new user
      repo.set(signInResult.user, mergedData);
    });
}).catch((error) => {
  // If there are errors we want to undo the data merge/deletion
  console.log("Sign In Error", error);
  repo.set(prevUser, prevUserData);
});
    link-multiple-accounts.js

如要在現有使用者帳戶中新增電子郵件地址和密碼憑證，請按照下列步驟操作：

  1. 使用任何驗證提供者或方法登入使用者。
  2. 提示使用者輸入電子郵件地址和新密碼。
  3. 使用電子郵件地址和密碼建立 AuthCredential 物件：

    Web

    import { EmailAuthProvider } from "firebase/auth";

const credential = EmailAuthProvider.credential(email, password);
    auth_make_email_credential.js

    Web

    var credential = firebase.auth.EmailAuthProvider.credential(email, password);
    link-multiple-accounts.js

  4. 將 AuthCredential 物件傳遞至已登入使用者的 linkWithCredential 方法：

    Web

    import { getAuth, linkWithCredential } from "firebase/auth";

const auth = getAuth();
linkWithCredential(auth.currentUser, credential)
  .then((usercred) => {
    const user = usercred.user;
    console.log("Account linking success", user);
  }).catch((error) => {
    console.log("Account linking error", error);
  });
    auth_simple_link.js

    Web

    auth.currentUser.linkWithCredential(credential)
  .then((usercred) => {
    var user = usercred.user;
    console.log("Account linking success", user);
  }).catch((error) => {
    console.log("Account linking error", error);
  });
    link-multiple-accounts.js

    如果憑證已連結至其他使用者帳戶，對 linkWithCredential 的呼叫就會失敗。在這種情況下，您必須根據應用程式的需求，適當處理帳戶和相關聯資料的合併作業 (請參閱上述範例)。

您可以取消驗證服務供應器與帳戶的連結，讓使用者無法再透過該供應器登入。

如要取消驗證服務供應器與使用者帳戶的連結，請將供應器 ID 傳遞至 unlink 方法。您可以從 providerData 屬性取得與使用者連結的驗證提供者 ID。

Web

import { getAuth, unlink } from "firebase/auth";

const auth = getAuth();
unlink(auth.currentUser, providerId).then(() => {
  // Auth provider unlinked from account
  // ...
}).catch((error) => {
  // An error happened
  // ...
});
auth_unlink_provider.js

Web

user.unlink(providerId).then(() => {
  // Auth provider unlinked from account
  // ...
}).catch((error) => {
  // An error happened
  // ...
});
link-multiple-accounts.js