I added a new field to the class CloudNote, now I am getting an error! I am getting the error when the app is trying to display a list.

Here is all my code without adding the field :: https://github.com/casas1010/flutter_firebase_vendor_management

I know its a simple issue, but I have tried to troubleshoot this for like an hour and have not made any progress

CloudNote class::

import 'package:cloud_firestore/cloud_firestore.dart';
import '/services/cloud/cloud_storage_constants.dart';
import 'package:flutter/foundation.dart';

/*
https://youtu.be/VPvVD8t02U8?t=87934
*/

@immutable
class CloudNote {
  final String documentId;
  final String jobCreatorId;
  final String jobDescription;
  final String jobState;        // I added this
  const CloudNote({
    required this.documentId,
    required this.jobCreatorId,
    required this.jobDescription,
    required this.jobState,      // I added this
  });

  // acts as constructor
  CloudNote.fromSnapshot(QueryDocumentSnapshot<Map<String, dynamic>> snapshot)
      : documentId = snapshot.id,
        jobCreatorId = snapshot.data()[jobCreatorIdColumn],
        jobState = snapshot.data()[jobStateColumn],           // I added this
        jobDescription = snapshot.data()[jobDescriptionColumn] as String;
}

notes view ::

import 'package:flutter/material.dart';
import '/constants/routes.dart';
import '/enums/menu_action.dart';
import '/services/auth/auth_service.dart';
import '/services/cloud/cloud_note.dart';
import '/services/cloud/firebase_cloud_storage.dart';
import '/utilities/dialogs/logout_dialog.dart';
import '/views/notes/notes_list_view.dart';

class NotesView extends StatefulWidget {
  const NotesView({Key? key}) : super(key: key);

  @override
  _NotesViewState createState() => _NotesViewState();
}

class _NotesViewState extends State<NotesView> {
  late final FirebaseCloudStorage _notesService;
  String get userId => AuthService.firebase().currentUser!.id;

  @override
  void initState() {
    _notesService = FirebaseCloudStorage();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Your jobs'),
        actions: [
          IconButton(
            onPressed: () {
              Navigator.of(context).pushNamed(createOrUpdateNoteRoute);
            },
            icon: const Icon(Icons.add),
          ),
          PopupMenuButton<MenuAction>(
            onSelected: (value) async {
              switch (value) {
                case MenuAction.logout:
                  final shouldLogout = await showLogOutDialog(context);
                  if (shouldLogout) {
                    await AuthService.firebase().logOut();
                    Navigator.of(context).pushNamedAndRemoveUntil(
                      loginRoute,
                      (_) => false,
                    );
                  }
              }
            },
            itemBuilder: (context) {
              return const [
                PopupMenuItem<MenuAction>(
                  value: MenuAction.logout,
                  child: Text('Log out'),
                ),
              ];
            },
          )
        ],
      ),
      body: StreamBuilder(
        stream: _notesService.allNotes(jobCreatorId: userId),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.waiting:
            case ConnectionState.active:
              if (snapshot.hasData) {
                final allNotes = snapshot.data as Iterable<CloudNote>;
                return NotesListView(
                  notes: allNotes,
                  onDeleteNote: (note) async {
                    await _notesService.deleteNote(documentId: note.documentId);
                  },
                  onTap: (note) {
                    Navigator.of(context).pushNamed(
                      createOrUpdateNoteRoute,
                      arguments: note,
                    );
                  },
                );
              } else {
                return const CircularProgressIndicator();
              }
            default:
              return const CircularProgressIndicator();
          }
        },
      ),
    );
  }
}

Error

The following _TypeError was thrown building NotesListView(dirty):
type 'Null' is not a subtype of type 'String'

The relevant error-causing widget was
NotesListView
lib/…/notes/notes_view.dart:72
When the exception was thrown, this was the stack
#0      new CloudNote.fromSnapshot
package:ijob_clone_app/…/cloud/cloud_note.dart:26
#1      FirebaseCloudStorage.allNotes.<anonymous closure>.<anonymous closure>
package:ijob_clone_app/…/cloud/firebase_cloud_storage.dart:39
#2      MappedListIterable.elementAt (dart:_internal/iterable.dart:413:31)
#3      ListIterator.moveNext (dart:_internal/iterable.dart:342:26)
#4      WhereIterator.moveNext (dart:_internal/iterable.dart:438:22)
#5      Iterable.length (dart:core/iterable.dart:497:15)
#6      NotesListView.build
package:ijob_clone_app/…/notes/notes_list_view.dart:26
#7      StatelessElement.build
package:flutter/…/widgets/framework.dart:4949
#8      ComponentElement.performRebuild
package:flutter/…/widgets/framework.dart:4878
#9      Element.rebuild
package:flutter/…/widgets/framework.dart:4604
#10     ComponentElement._firstBuild
package:flutter/…/widgets/framework.dart:4859
#11     ComponentElement.mount
package:flutter/…/widgets/framework.dart:4853
#12     Element.inflateWidget
package:flutter/…/widgets/framework.dart:3863
#13     Element.updateChild
package:flutter/…/widgets/framework.dart:3586
#14     ComponentElement.performRebuild
package:flutter/…/widgets/framework.dart:4904
#15     StatefulElement.performRebuild
package:flutter/…/widgets/framework.dart:5050
#16     Element.rebuild
package:flutter/…/widgets/framework.dart:4604
#17     BuildOwner.buildScope
package:flutter/…/widgets/framework.dart:2667
#18     WidgetsBinding.drawFrame
package:flutter/…/widgets/binding.dart:882
#19     RendererBinding._handlePersistentFrameCallback
package:flutter/…/rendering/binding.dart:378
#20     SchedulerBinding._invokeFrameCallback
package:flutter/…/scheduler/binding.dart:1175
#21     SchedulerBinding.handleDrawFrame
package:flutter/…/scheduler/binding.dart:1104
#22     SchedulerBinding._handleDrawFrame
package:flutter/…/scheduler/binding.dart:1015
#23     _invoke (dart:ui/hooks.dart:148:13)
#24     PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:318:5)
#25     _drawFrame (dart:ui/hooks.dart:115:31)
════════════════════════════════════════════════════════════════════════════════

NotesListView ::

import 'package:flutter/material.dart';
import '/services/cloud/cloud_note.dart';
import '/utilities/dialogs/delete_dialog.dart';
/*
source: https://www.youtube.com/watch?v=VPvVD8t02U8&t=59608s
class creation :: 22:02:54
 */

typedef NoteCallback = void Function(CloudNote note);

class NotesListView extends StatelessWidget {
  final Iterable<CloudNote> notes; // list of notes
  final NoteCallback onDeleteNote;
  final NoteCallback onTap;

  const NotesListView({
    Key? key,
    required this.notes,
    required this.onDeleteNote,
    required this.onTap,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: notes.length,
      itemBuilder: (context, index) {
        final note =
            notes.elementAt(index); // current note whose data we are returning
        return ListTile(
          onTap: () {
            onTap(note);
          },
          title: Text(
            note.jobDescription,
            maxLines: 1,
            softWrap: true,
            overflow: TextOverflow.ellipsis,
          ),
          trailing: IconButton(
            onPressed: () async {
              final shouldDelete = await showDeleteDialog(context);
              if (shouldDelete) {
                onDeleteNote(note);
              }
            },
            icon: const Icon(Icons.delete),
          ),
        );
      },
    );
  }
}

CodePudding user response：

This happens if you forget to update your Firestore entries. Atleast one of your CloudNote entries in Firestore does not have the field jobState. That's why Firestore returns a Null value. But it tries to map to String which leads to an exception.

CodePudding user response：

Make sure to rerun the project. or flutter clean and then flutter run