The method 'document' isn't defined for the type 'CollectionReference'. Flutter/Firebase

Question

The method 'document' isn't defined for the type 'CollectionReference'. Try correcting the name to the name of an existing method, or defining a method named 'document'.

I am getting this error in my project. Can you help me?

My Code:

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:crypto_app/models/users.dart';

class FireStoreService {
  final FirebaseFirestore _firestore = FirebaseFirestore.instance;
  final DateTime time = DateTime.now();

  Future<void> createUser({id, mail, userName, photoUrl = ""}) async {
    await _firestore.collection("users").doc(id).set({
      "userName": userName,
      "mail": mail,
      "photoUrl": photoUrl,
      "about": "",
      "createTime": time
    });
  }

  Future<Users> bringUser(id) async {
    DocumentSnapshot doc = await _firestore.collection("users").doc(id).get();
    if (doc.exists) {
      Users users = Users.dokumandanUret(doc);
      return users;
    }
    return null;
  }

  void userUpdate({String userId, String userName, String photoUrl = ""}) {
    _firestore
        .collection("users")
        .document(userId)
        .updateData({"userName": userName, "photoUrl": photoUrl});
  }
}

Solution

CollectionReference in cloud_firestore for flutter/dart does not have a document(..) method. It is called doc(..) instead. https://pub.dev/documentation/cloud_firestore/latest/cloud_firestore/CollectionReference/doc.html