使用Flutter+FCM的sendMulticast时，如何添加FLUTTER_NOTIFICATION_CLICK？

核心问题：字段名格式错误 #

你添加的clickAction是驼峰命名，但FCM的通知负载字段要求使用下划线命名的click_action，这是导致发送失败的直接原因。修正字段名即可解决该问题，同时建议补充自定义数据用于后续页面跳转。

修改后的Firebase Function代码 #

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

exports.sendNotificationToFCMToken = functions.firestore.document("chat_rooms/{chatRoomId}/messages/{messageId}")
.onCreate(async (snapshot: functions.firestore.QueryDocumentSnapshot, context) => {
  const senderUid: string = snapshot.data().sender_uid;
  const recipientsUid: string[] = snapshot.data().recipients_uid;
  const message: string = snapshot.data().message;
  const chatRoomId = context.params.chatRoomId; // 获取房间ID用于跳转参数传递

  const db = admin.firestore();
  const fcm = admin.messaging();

  // 替换forEach为for...of，确保异步操作按顺序执行
  for (const uid of recipientsUid) {
    const recipientTokensSnapshot = await db
      .collection("users_data")
      .doc(uid)
      .collection("tokens")
      .get();

    const recipientTokens = recipientTokensSnapshot
      .docs.map((doc) => doc.data().token);

    const notificationPayload = {
      notification: {
        title: senderUid,
        body: message,
        click_action: "FLUTTER_NOTIFICATION_CLICK" // 修正为下划线命名的字段
      },
      data: {
        // 添加自定义数据，用于Flutter端判断跳转目标页面
        screen: "/chat-room",
        chatRoomId: chatRoomId
      },
      tokens: recipientTokens,
    };

    const response = await fcm.sendMulticast(notificationPayload);
    console.log(`给用户${uid}发送通知：${response.successCount}成功，${response.failureCount}失败`);
  }
});

额外关键配置 #

1. AndroidManifest.xml 配置
   在Flutter项目的android/app/src/main/AndroidManifest.xml中，给MainActivity添加对应的intent filter，确保点击通知能唤起应用：

<activity
    android:name=".MainActivity"
    android:exported="true">
    <!-- 原有配置保持不变 -->
    <intent-filter>
        <action android:name="FLUTTER_NOTIFICATION_CLICK" />
        <category android:name="android.intent.category.DEFAULT" />
    </intent-filter>
</activity>

2. Flutter端处理通知点击
   在Flutter代码中监听通知打开事件，根据payload中的data字段跳转到指定页面：

import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/material.dart';

void setupNotificationListener(BuildContext context) {
  // 处理应用处于后台时点击通知的情况
  FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
    final String? targetScreen = message.data['screen'];
    if (targetScreen == '/chat-room') {
      final String? chatRoomId = message.data['chatRoomId'];
      Navigator.pushNamed(
        context,
        targetScreen,
        arguments: chatRoomId,
      );
    }
  });

  // 处理应用完全关闭时点击通知的情况（建议在MaterialApp初始化后调用）
  FirebaseMessaging.instance.getInitialMessage().then((RemoteMessage? message) {
    if (message != null) {
      final String? targetScreen = message.data['screen'];
      if (targetScreen == '/chat-room') {
        final String? chatRoomId = message.data['chatRoomId'];
        Navigator.pushNamed(
          context,
          targetScreen,
          arguments: chatRoomId,
        );
      }
    }
  });
}

注意事项 #

• 原代码使用forEach(async (uid) => {})会导致异步操作无法按顺序执行，函数可能提前结束，改用for...of循环可保证每个用户的通知发送完成后再处理下一个。
• data字段中的自定义参数可根据业务需求调整，用于传递跳转所需的页面参数。

内容的提问来源于stack exchange，提问作者David A.