使用 JavaScript 将多个身份验证提供方与一个帐号相关联

您可以通过将多个身份验证提供方凭据关联至现有用户帐号，让用户可以使用多个身份验证提供方登录您的应用。无论用户使用哪个身份验证提供方登录，系统均可通过同一 Firebase 用户 ID 识别用户。例如，使用密码登录的用户可以关联 Google 帐号，以后便可使用这两种方法中的任意一种登录。或者，匿名用户可以关联 Facebook 帐号，以后就可以使用 Facebook 帐号登录并继续使用您的应用。

准备工作

为您的应用增加对两个或多个身份验证提供方（可能包括匿名身份验证）的支持。

将联合身份验证提供方凭据与用户帐号关联

如需将如 Google 或 Facebook 等身份验证提供方的凭据与现有用户帐号关联，请按以下步骤操作：

使用任意身份验证提供方或方法让用户登录。

获取要关联至用户帐号的提供方所对应的 AuthProvider 对象。示例：

Web version 9

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 version 8

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

提示用户使用要关联的提供方进行登录。您可以通过弹出式窗口或重定向至提供方的登录页面，提示用户进行登录。在移动设备上最好使用重定向方法。

如需使用弹出式窗口登录，请调用 linkWithPopup：

Web version 9

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 version 8

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

如需重定向到提供方的登录页面进行登录，请调用 linkWithRedirect：使用“linkWithRedirect”时，请遵循最佳实践。

Web version 9

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 version 8

auth.currentUser.linkWithRedirect(provider)
  .then(/* ... */)
  .catch(/* ... */);link-multiple-accounts.js

用户在登录之后会被重定向回您的页面。然后，您可以在页面加载时调用 getRedirectResult 来检索登录结果：

Web version 9

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 version 8

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

如果用户成功登录，系统就会将用户的提供方帐号与用户在您的 Firebase 项目中的帐号相关联。

如果凭据已与另一用户帐号关联，帐号关联将失败。在这种情况下，您必须根据需要为您的应用合并帐号和相关数据：

Web version 9

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 version 8

// 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

将电子邮件地址和密码凭据与用户帐号相关联

如需将电子邮件地址和密码凭据添加到现有用户帐号，请按以下步骤操作：

使用任意身份验证提供方或方法让用户登录。
提示用户输入电子邮件地址和新密码。

使用电子邮件地址和密码创建一个 AuthCredential 对象：

Web version 9

import { EmailAuthProvider } from "firebase/auth";

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

Web version 8

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

将 AuthCredential 对象传递给已登录用户的 linkWithCredential 方法：

Web version 9

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 version 8

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

如果凭据已与另一用户帐号关联，则无法调用 linkWithCredential。在这种情况下，您必须根据需要为您的应用合并帐号和相关数据（请参阅上方示例）。

取消身份验证提供方与用户帐号的关联

您可以取消身份验证提供方与帐号的关联，这样用户就无法再通过该提供方登录了。

如需解除身份验证提供方与用户帐号的关联，请将提供方 ID 传递给 unlink 方法。您可以从 providerData 属性中获取与用户相关联的身份验证提供方的 ID。

Web version 9

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 version 8

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