React.js中Firebase云函数实现FCM推送遇非空对象错误求助

我首次尝试在React.js应用中通过Firebase实时数据库云函数实现FCM推送通知，目前遇到如下错误：

error: Message must be a non-null object

查阅相关解决方案无效，不清楚代码具体问题所在，以下是functions目录下的index.js代码：

const functions = require('firebase-functions');
const admin = require("firebase-admin");
admin.initializeApp();

exports.observeFollow = functions.database
  .ref('/notifications/{userEmail}/{uid}')
  .onCreate(async (snapshot, context) => {
    const userEmail = context.params.userEmail;
    const uid = context.params.uid;
    const notificationData = snapshot.val();

    console.log("📥 New Notification:", notificationData);
    console.log('📥 Sender Name:', notificationData.senderName);

    // 获取被关注用户（应该在/users/{userEmail}路径下）
    const userRef = admin.database().ref(userEmail);
    const userSnap = await userRef.once('value');

    if (!userSnap.exists()) {
      console.error('❌ User not found for: ${userEmail}');
      return null;
    }

    const followedUser = userSnap.val();
    const fcmToken = followedUser.fcmToken;

    console.log('FCMTOKEN------:' + fcmToken);
    console.log('followedUser Data------:' + followedUser);

    if (!fcmToken || fcmToken.length < 100) {
      console.warn('⚠️ Invalid FCM token for user ${userEmail}:', fcmToken);
      return null;
    }

    const payload = {
      notification: {
        title: 'You have a new connection!',
        body: 'Wayne wants to connect.',
      }
    };

    // const message = {
    //   token: fcmToken,
    //   notification: {
    //     title: "You have a new connection!",
    //     body:  'Wayne wants to connect.';
    //   }
    // };

    try {
      const response = await admin.messaging().send(fcmToken, payload);
      console.log('✅ Message sent:', response);
    } catch (error) {
      console.error('❌ Error sending FCM:', error);
    }

    return null;
  });

Firebase函数日志：

错误原因与修复方案 #

错误根源是调用admin.messaging().send()的方式不符合SDK要求：该方法仅接受单个消息对象作为参数，而非分开传递token和payload。

核心修复步骤：

1. 合并token与通知内容为统一的消息对象
2. 修正注释代码中的语法错误（body字段末尾多余的分号）
3. 替换错误的send()调用方式

修复后的核心代码片段：

// 正确构建消息对象
const message = {
  token: fcmToken,
  notification: {
    title: 'You have a new connection!',
    body: `${notificationData.senderName} wants to connect.` // 动态使用发送者名称
  }
};

try {
  const response = await admin.messaging().send(message); // 仅传入消息对象
  console.log('✅ Message sent:', response);
} catch (error) {
  console.error('❌ Error sending FCM:', error);
}

额外需要修复的两个问题：

• 数据库路径错误：原代码中userRef路径缺少/users前缀，应改为admin.database().ref('/users/' + userEmail)，否则无法正确获取用户数据
• 字符串模板语法错误：所有使用${变量}的地方必须用反引号`包裹字符串，例如：

  console.error(`❌ User not found for: ${userEmail}`);
  console.warn(`⚠️ Invalid FCM token for user ${userEmail}:`, fcmToken);
  

完整修复后的index.js代码：

const functions = require('firebase-functions');
const admin = require("firebase-admin");
admin.initializeApp();

exports.observeFollow = functions.database
  .ref('/notifications/{userEmail}/{uid}')
  .onCreate(async (snapshot, context) => {
    const userEmail = context.params.userEmail;
    const uid = context.params.uid;
    const notificationData = snapshot.val();

    console.log("📥 New Notification:", notificationData);
    console.log('📥 Sender Name:', notificationData.senderName);

    // 获取被关注用户（修正路径：添加/users前缀）
    const userRef = admin.database().ref(`/users/${userEmail}`);
    const userSnap = await userRef.once('value');

    if (!userSnap.exists()) {
      console.error(`❌ User not found for: ${userEmail}`);
      return null;
    }

    const followedUser = userSnap.val();
    const fcmToken = followedUser.fcmToken;

    console.log('FCMTOKEN------:' + fcmToken);
    console.log('followedUser Data------:', followedUser); // 改用逗号避免对象转字符串失真

    if (!fcmToken || fcmToken.length < 100) {
      console.warn(`⚠️ Invalid FCM token for user ${userEmail}:`, fcmToken);
      return null;
    }

    // 正确构建FCM消息对象
    const message = {
      token: fcmToken,
      notification: {
        title: 'You have a new connection!',
        body: `${notificationData.senderName} wants to connect.`
      }
    };

    try {
      const response = await admin.messaging().send(message);
      console.log('✅ Message sent:', response);
    } catch (error) {
      console.error('❌ Error sending FCM:', error);
    }

    return null;
  });

内容的提问来源于stack exchange，提问作者Iam Wayne