DB Sqflite Flutter 中的数据未更新

Question

The task text in edit_todo_screen is not updated. I'm using the same code as in item_tasks , where I change the status of the task to move between "Done" and "Archived" - everything works well here. I tried to change only the status in edit_todo_screen , but it does not change, although the code is identical to the code in item_tasks . Perhaps the problem is that I'm not passing the parameters correctly to edit_todo_screen . I need to be able to change the status of the task and the text of the task itself in edit_todo_screen . Attached below is a screenshot of the error that occurs when clicking the button in edit_todo_screen Tell me, please, what could be my mistake?

cubit_db

 class AppCubit extends Cubit<AppStates> {
      AppCubit() : super(AppInitialState());
    
      static AppCubit get(context) => BlocProvider.of(context);
    
    void updateDatabase(String status, int id) async {
        database!.rawUpdate(
            'UPDATE tasks SET status = ? WHERE id = ?', [status, id]).then((value) {
          getDataBase(database);
          emit(AppUpdateDatabaseState());
        });
      }

new_tasks_list

class NewTasksScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return BlocConsumer<AppCubit, AppStates>(
      listener: (context, state) {},
      builder: (context, state) {
        var tasks = AppCubit.get(context).newTasks;
        return SingleChildScrollView(
          child: Column(children: [
            ListView.builder(
              physics: const NeverScrollableScrollPhysics(),
              shrinkWrap: true,
              itemCount: tasks.length,
              itemBuilder: (context, index) => TaskItem(tasks: tasks[index]),
            ),
          ]),
        );
      },
    );

tasks_item

class TaskItem extends StatelessWidget {
  Map? tasks;

  TaskItem({this.tasks});
  @override
  Widget build(BuildContext context) {
    return Card(
      key: Key(tasks!['title']),
      shadowColor: Colors.blueGrey,
      margin: const EdgeInsets.only(left: 15, right: 15, top: 8),
      color: Colors.black,
      shape: RoundedRectangleBorder(
        side: BorderSide(color: Colors.grey.shade800, width: 0.5),
        borderRadius: BorderRadius.circular(10),
      ),
      borderOnForeground: false,
      child: ListTile(
        title: Column(crossAxisAlignment: CrossAxisAlignment.start, children: [
          Text(
            // '${state.loadedUser[index].description}',
            tasks!['title'],
            style: const TextStyle(
              fontSize: 21.0,
              // fontWeight: FontWeight.bold,
            ),
          ),
          // Text(
          //   tasks!['status'],
          //   style: const TextStyle(fontSize: 21.0),
          // ),
        ]),
        trailing: IconButton(
          tooltip: 'Archive Todo',
          highlightColor: Colors.red,
          onPressed: () {
            AppCubit.get(context).updateDatabase('Archive', tasks!['id']);
          },
          icon: const Icon(
            Icons.archive,
            color: Colors.white,
          ),
        ),
        leading: IconButton(
          tooltip: 'Done Todo',
          highlightColor: Colors.green,
          onPressed: () {
            AppCubit.get(context).updateDatabase('Done', tasks!['id']);
          },
          icon: const Icon(
            Icons.check,
            color: Colors.white,
          ),
        ),
        onTap: () {
          Navigator.push(
            context,
            MaterialPageRoute(
              builder: (context) => EditTodoScreen(
                title: tasks!['title'],
                id: tasks!['id'],
              ),
            ),
          );
        },
      ),
    );
  }
}

edit_todo_screen

class EditTodoScreen extends StatelessWidget {
  // Map? tasks;
  String title;
  int id;
  EditTodoScreen({Key? key, required this.title, required this.id})
      : super(key: key);

  final _controller = TextEditingController();

  @override
  Widget build(BuildContext context) {
    _controller.text = title;

    return BlocConsumer<AppCubit, AppStates>(
        listener: (context, state) {},
        builder: (context, state) {
          return Scaffold(
            appBar: AppBar(
              title: const Text(
                'Edit Todo',
                style: TextStyle(fontSize: 20.0),
              ),
            ),
            body: _body(context),
          );
        });
  }

  Widget _body(context) {
    return Padding(
      padding: const EdgeInsets.all(20.0),
      child: Column(
        children: [
          TextFormField(
            controller: _controller,
            autocorrect: true,
            maxLines: 2,
            decoration: const InputDecoration(hintText: 'Enter todo message'),
          ),
          const SizedBox(
            height: 10.0,
          ),
          // ElevatedButton(
          //   // style:,
          //   onPressed: () {
          //     AppCubit.get(context).updateDatabase('Done', id);
          //   },
          //   child: Text(
          //     'Update Data',
          //     style: TextStyle(color: Colors.amber.shade700),
          //   ),
          // ),
          InkWell(
            onTap: () {
              AppCubit.get(context).updateDatabase('Done', id);
              Navigator.pop(context);
            },
            child: _updateBtn(context),
          )
        ],
      ),
    );
  }

  Widget _updateBtn(context) {
    return Container(
      width: MediaQuery.of(context).size.width,
      height: 50.0,
      decoration: BoxDecoration(
          color: Colors.black, borderRadius: BorderRadius.circular(10.0)),
      child: Center(
        child: Text(
          'Update Todo',
          style: TextStyle(
              fontSize: 17.0,
              color: Colors.amber.shade700,
              fontWeight: FontWeight.bold),
        ),
      ),
    );
  }
}

Answer 1

I think your problem has to do with the fact that database is not set in the second case. The code fails because you try to access a null value that then is checked with the "." operator. Look where you set the database and check if that code is called in both code flows.