Error while retrieving data from Firebase(The getter 'cover' was called on null.)

Question

I am trying to call data from Firebase but I found the below error, while start login for first time, and this is the below error:

The following NoSuchMethodError was thrown building BlocBuilder<AppCubit, AppStates>(dirty, state: _BlocBuilderBaseState<AppCubit, AppStates>#b335d):
The getter 'cover' was called on null.
Receiver: null
Tried calling: cover

and this is the below related code:

                          image: DecorationImage(
                            image: NetworkImage(
                              '${userModel.cover}',
                            ),
                            fit: BoxFit.cover,
                          ),

and this is the full code I have :

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:mysocially/shared/cubit/cubit.dart';
import 'package:mysocially/shared/cubit/states.dart';
import 'package:mysocially/styles/icon_broken.dart';

class SettingsScreen extends StatelessWidget {
  const SettingsScreen({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return BlocConsumer<AppCubit, AppStates>(
      listener: (context, state) {},
      builder: (context, state) {
        var userModel = AppCubit.get(context).model;

        return Padding(
          padding: const EdgeInsets.all(8.0),
          child: Column(
            children: [
              Container(
                height: 190.0,
                child: Stack(
                  alignment: AlignmentDirectional.bottomCenter,
                  children: [
                    Align(
                      alignment: AlignmentDirectional.topCenter,
                      child: Container(
                        width: double.infinity,
                        height: 140.0,
                        decoration: BoxDecoration(
                          borderRadius: BorderRadius.only(
                            topLeft: Radius.circular(4.0),
                            topRight: Radius.circular(4.0),
                          ),
                          image: DecorationImage(
                            image: NetworkImage(
                              '${userModel.cover}',
                            ),
                            fit: BoxFit.cover,
                          ),
                        ),
                      ),
                    ),
                    CircleAvatar(
                      radius: 51.0,
                      backgroundColor:
                          Theme.of(context).scaffoldBackgroundColor,
                      child: CircleAvatar(
                        // radius: responsive.height * 0.025,
                        radius: 50.0,
                        backgroundImage: NetworkImage(
                          '${userModel.image}',
                        ),
                      ),
                    ),
                  ],
                ),
              ),
              SizedBox(
                height: 5.0,
              ),
              Text(
                '${userModel.name}',
                style: Theme.of(context).textTheme.bodyText1,
              ),
              Text(
                '${userModel.bio}',
                style: Theme.of(context).textTheme.caption,
              ),
              Padding(
                padding: const EdgeInsets.symmetric(vertical: 20.0),
                child: Row(
                  children: [
                    Expanded(
                      child: InkWell(
                        child: Column(
                          children: [
                            Text(
                              '100',
                              style: Theme.of(context).textTheme.subtitle2,
                            ),
                            Text(
                              'Posts',
                              style: Theme.of(context).textTheme.caption,
                            ),
                          ],
                        ),
                        onTap: () {},
                      ),
                    ),
                    Expanded(
                      child: InkWell(
                        child: Column(
                          children: [
                            Text(
                              '100',
                              style: Theme.of(context).textTheme.subtitle2,
                            ),
                            Text(
                              'Posts',
                              style: Theme.of(context).textTheme.caption,
                            ),
                          ],
                        ),
                        onTap: () {},
                      ),
                    ),
                    Expanded(
                      child: InkWell(
                        child: Column(
                          children: [
                            Text(
                              '62',
                              style: Theme.of(context).textTheme.subtitle2,
                            ),
                            Text(
                              'Photos',
                              style: Theme.of(context).textTheme.caption,
                            ),
                          ],
                        ),
                        onTap: () {},
                      ),
                    ),
                    Expanded(
                      child: InkWell(
                        child: Column(
                          children: [
                            Text(
                              '200',
                              style: Theme.of(context).textTheme.subtitle2,
                            ),
                            Text(
                              'Followers',
                              style: Theme.of(context).textTheme.caption,
                            ),
                          ],
                        ),
                        onTap: () {},
                      ),
                    ),
                    Expanded(
                      child: InkWell(
                        child: Column(
                          children: [
                            Text(
                              '600',
                              style: Theme.of(context).textTheme.subtitle2,
                            ),
                            Text(
                              'Followings',
                              style: Theme.of(context).textTheme.caption,
                            ),
                          ],
                        ),
                        onTap: () {},
                      ),
                    ),
                  ],
                ),
              ),
              Row(
                children: [
                  Expanded(
                    child: OutlinedButton(
                      onPressed: () {},
                      child: Text('Add Photos'),
                    ),
                  ),
                  SizedBox(width: 10.0,),
                  OutlinedButton(
                    onPressed: () {},
                    child: Icon(
                      IconBroken.Edit,
                      size: 20.0,
                    ),
                  ),
                ],
              ),
            ],
          ),
        );
      },
    );
  }
}

cubit class which containes the business logic:

class AppCubit extends Cubit<AppStates> {
  AppCubit() : super(AppInitialState());

  static AppCubit get(context) => BlocProvider.of(context);

  UserModel model;

  void getUserData() {
    emit(AppGetUserLoadingState());
    FirebaseFirestore.instance.collection('users').doc(uId).get().then((value) {
      // print(value.data());
      model = UserModel.fromJson(value.data());
      emit(
        AppGetUserSuccessState(),
      );
    }).catchError((error) {
      print(error.toString());
      emit(
        AppGetUserErrorState(
          error.toString(),
        ),
      );
    });
  }
}

The code works Fine when I make hot reload or restart the app but it gives this error first Failed to load providerinstaller module: No acceptable module found. Local version is 0 and remote version is 0. and then show the data...

So How can I solve this problem?

Answer 1

Since you are using BLoC, you should get the user model from it like this:

final userModel = state.model;

and not like this:

var userModel = AppCubit.get(context).model;

Also, when you only need to get the state of the cubit (for widget building), use BlocBuilder and not a BlocConsumer.