Next.js App Router中NextAuth Firebase适配器用户与会话异常问题

问题现象 #

• 启用Firestore适配器后，Credentials凭证登录始终处于未认证状态，Firestore数据库中无用户数据写入
• 移除适配器后，所有登录方式功能恢复正常
• Google、GitHub、Discord等第三方登录在启用适配器时可正常工作，仅凭证登录出现异常

NextAuth配置代码 #

export const authOptions : NextAuthOptions = {
    pages: {
        signIn: '/auth/login',
    },
    providers: [
        CredentialsProvider({
            name: "Credentials",
            credentials: {  },
            async authorize(credentials) : Promise<any> {
                return await signInWithEmailAndPassword(auth, (credentials as any).email || '', (credentials as any).password || '')
                    .then(userCredential => {
                        if (userCredential.user) {
                            return userCredential.user
                        }
                        return null
                    })
                .catch(error => console.log(error))
            }
        }),
        GoogleProvider({
            clientId: process.env.GOOGLE_CLIENT_ID!,
            clientSecret: process.env.GOOGLE_CLIENT_SECRET!
        }),
        GitHubProvider({
            clientId: process.env.GITHUB_CLIENT_ID!,
            clientSecret: process.env.GITHUB_CLIENT_SECRET!
        }),
        DiscordProvider({
            clientId: process.env.DISCORD_CLIENT_ID,
            clientSecret: process.env.DISCORD_CLIENT_SECRET
        }),
    ],
    /* adapter: FirestoreAdapter({
        credential: cert({
          projectId: process.env.FIREBASE_PROJECT_ID,
          clientEmail: process.env.FIREBASE_CLIENT_EMAIL,
          privateKey: process.env.FIREBASE_PRIVATE_KEY!.replace(/\\n/g, '\n')
        })
      }) */
    // adapter: FirestoreAdapter(db.app)
}

export default NextAuth(authOptions)

凭证注册代码 #

const signup = (formdata : FormData) => {
setEmail((formdata.get("email") as string))
setPassword((formdata.get("password") as string))
createUserWithEmailAndPassword(auth, email, password).then(res => {
  console.log(res)
});
router.push("/dashboard")
}

第三方提供商注册代码 #

function Signup(provider : string) {
signIn(provider)
} 
// provider 取值为 google、github、discord

解决方案 #

1. 修正CredentialsProvider的返回格式 #

Firestore适配器要求authorize方法返回符合NextAuth规范的用户对象，直接返回Firebase Auth的用户实例会缺少必要字段。修改authorize方法：

async authorize(credentials): Promise<any> {
  try {
    const userCredential = await signInWithEmailAndPassword(auth, credentials.email || '', credentials.password || '')
    const user = userCredential.user
    // 转换为适配器兼容的用户结构
    return {
      id: user.uid,
      name: user.displayName,
      email: user.email,
      emailVerified: user.emailVerified,
      image: user.photoURL
    }
  } catch (error) {
    console.error(error)
    return null
  }
}

2. 正确初始化Firebase适配器 #

使用Firebase Admin SDK的初始化实例来配置适配器，避免直接传递凭证：

// 单独文件初始化Firebase Admin
import { initializeApp, getApps, cert } from 'firebase-admin/app'
import { getFirestore } from 'firebase-admin/firestore'

const serviceAccount = {
  projectId: process.env.FIREBASE_PROJECT_ID,
  clientEmail: process.env.FIREBASE_CLIENT_EMAIL,
  privateKey: process.env.FIREBASE_PRIVATE_KEY!.replace(/\\n/g, '\n')
}

if (!getApps().length) {
  initializeApp({ credential: cert(serviceAccount) })
}

const db = getFirestore()

// 在NextAuth配置中使用
adapter: FirestoreAdapter(db)

3. 完善凭证注册流程 #

当前注册仅创建Firebase用户，未触发NextAuth登录流程，导致状态无法同步。修改注册函数：

const signup = async (formdata: FormData) => {
  const email = formdata.get("email") as string
  const password = formdata.get("password") as string
  try {
    await createUserWithEmailAndPassword(auth, email, password)
    // 创建用户后调用NextAuth完成登录
    await signIn('credentials', { email, password, redirect: false })
    router.push("/dashboard")
  } catch (error) {
    console.error(error)
  }
}

4. 验证权限与环境变量 #

• 确认Firebase服务账号拥有Firestore的写入权限（在Firebase控制台IAM中配置）
• 检查所有Firebase相关环境变量是否正确配置，确保privateKey的换行符替换逻辑生效

内容的提问来源于stack exchange，提问作者specter