小编Ema*_*per的帖子

当我运行我的应用程序时出现此错误，并且应用程序关闭时的后台通知不起作用：

firebase_messaging: ^7.0.3

final FirebaseMessaging firebaseMessaging = FirebaseMessaging();
  

  @override
  void initState() {
    super.initState();
    registerNotification();
  }



  void registerNotification() {
    firebaseMessaging.requestNotificationPermissions();

    firebaseMessaging.configure(onMessage: (Map<String, dynamic> message) {
      print('onMessage: $message');
      return ;
    }, onResume: (Map<String, dynamic> message) {
      print('onResume: $message');
      return Navigator.push(
          context,
          MaterialPageRoute(
              builder: (context) => NotificationsScreen()));
    }, onBackgroundMessage: _firebaseMessagingBackgroundHandler,
        onLaunch: (Map<String, dynamic> message) {
      print('onLaunch: $message');
      return;
    });

    firebaseMessaging.getToken().then((token) {
      print('token: $token');
      FirebaseFirestore.instance
          .collection('Consultant')
          .doc(firebaseUser.uid)
          .update({'deviceToken': token});
    }).catchError((err) {
      //Fluttertoast.showToast(msg: err.message.toString());
    });
  }

从课堂上出来：

Future<dynamic> _firebaseMessagingBackgroundHandler(
    Map<String, dynamic> message,
    ) async { …

我有一个名为“ Consultant我的应用程序从用户那里收集数据”的类。

class Consultant {
  final int id;
  final String consultantFirstName;
  final String consultantLastName;
  final String consultantNickName;
  final String consultantImageProfile;
  final String consultantCategory;
  final String consultantDescription;
  final String consultantLikes;
  final String consultantReviews;
  final String consultantStars;
  final String consultantPrice;
  final String consultantExperience;


  const Consultant({
    this.id,
    this.consultantFirstName,
    this.consultantLastName,
    this.consultantNickName,
    this.consultantImageProfile,
    this.consultantCategory,
    this.consultantDescription,
    this.consultantLikes,
    this.consultantReviews,
    this.consultantStars,
    this.consultantPrice,
    this.consultantExperience,
  });
}

下面是我的一位用户的示例：

final Consultant marco = Consultant(
    id: 1,
    consultantFirstName: 'Marco',
    consultantLastName: 'Marcello',
    consultantNickName: 'Tarot and Dreams',
    consultantCategory: 'Tarocchi',
    consultantDescription: 'Ciao a tutti …