Flutter: The getter 'userId' isn't defined for the class 'Object'-CodePudding

Edit: Actually I think I should be using the containsKey() method, but Dart doesn’t like that either.

I created a class of CloudGroup which I use to create a stream later. The field that is giving me trouble the groupMembersfield.

The way this field looks in my database is as follows:

groupMembers: { uid1: {...}, uid2: {...}, ... }

I have the type labeled as Object because it is a giant object with children. Why doesn't Dart like this? Thank you in advance. This is the rest of the code.

CloudGroup Class

@immutable
class CloudGroup {
  final String groupAdmin;
  final Object groupMembers;
  final String groupName;

  const CloudGroup({
    required this.groupAdmin,
    required this.groupMembers,
    required this.groupName,
  });

  CloudGroup.fromSnapshot(QueryDocumentSnapshot<Map<String, dynamic>> snapshot)
      : documentId = snapshot.id,
        groupAdmin = snapshot.data()[groupAdminFieldName],
        groupMembers = snapshot.data()[groupMembersFieldName],
        groupName = snapshot.data()[groupNameFieldName],
}

Stream Function

Stream<Iterable<CloudGroup>> allGroups({required String userId}) =>
      groups.snapshots().map((event) => event.docs
          .map((doc) => CloudGroup.fromSnapshot(doc))
          .where((group) => group.groupMembers.userId == userId));

The error occurs above at the .userId spot. I want to access the child keys to match with the userId provided.

Error

Error: The getter 'userId' isn't defined for the class 'Object'.

 - 'Object' is from 'dart:core'.
Try correcting the name to the name of an existing getter, or defining a getter or field named 'userId'.
          .where((group) => group.groupMembers.userId == userId));

If anyone does know the solution but also could explain it so I understand for the future, I would really appreciate it. Thank you again!

CodePudding user response：

In Your CloudGroup class, it has Instance variable named groupMembers

groupMembers's type is Object

This Object type is defined in core/object.dart and has no getter named 'userId'

If you want to use like groupMembers.userId

you have to make groupMembers class like

class GroupMembers {
 final int userId;
 // other instance variable you wants
}

then use

class CloudGroup {
  final String groupAdmin;
  final GroupMembers groupMembers;
  final String groupName;

  const CloudGroup({
    required this.groupAdmin,
    required this.groupMembers,
    required this.groupName,
  });

  CloudGroup.fromSnapshot(QueryDocumentSnapshot<Map<String, dynamic>> snapshot)
      : documentId = snapshot.id,
        groupAdmin = snapshot.data()[groupAdminFieldName],
        groupMembers = snapshot.data()[groupMembersFieldName],
        groupName = snapshot.data()[groupNameFieldName],
}

Here is link about Object class

https://api.flutter.dev/flutter/dart-core/Object-class.html

I hope this answer helps you