Flutter：从对象编辑新对象不正确地更改旧对象

Question

我正在尝试在我的生产力跟踪应用程序中包含一个编辑对象功能。我正在使用 Flutter、Firestore 和 Provider。我正在尝试允许用户在模态底部 sheet 中更新具有不同属性的任务（例如）。更新方面正在工作。如果用户按下更新按钮，它会正确更新 Firestore 并正确显示信息。我的问题是，当我取消模式时，发出取消更新的信号，它仍在更新原始任务对象。我什至尝试使用取消按钮来处理提供者，结果是一样的。我不确定为什么会这样。如果我重新加载应用程序，则会显示存储在 Firestore 中的正确值。这是正在发生的事情的视频：

这是我的任务模型：

class Task {
  String taskID;
  String taskName;
  Project project;
  Status status;
  DateTime dueDate;
  DateTime createDate;

  Task({taskID, taskName, project, status, dueDate, createDate})
      : taskID = taskID as String ?? '',
        taskName = taskName as String ?? '',
        project = project as Project ?? Project(),
        status = status as Status ?? Status(),
        dueDate = dueDate as DateTime ?? DateTime(0001, 01, 01, 0, 0, 0, 0, 555),
        createDate = createDate as DateTime ?? DateTime.now();

这是我的提供商状态：

class TaskEditState extends ChangeNotifier {
  Task newTask;

  TaskEditState({newTask}) : newTask = newTask as Task ?? Task();

  void updateTaskName(String taskName) {
    newTask.taskName = taskName;
    notifyListeners();
  }

  void updateTaskProject(Project project) {
    newTask.project = project;
    notifyListeners();
  }

  void updateTaskStatus(Status status) {
    newTask.status = status;
    notifyListeners();
  }

  void updateTaskDueDate(DateTime dueDate) {
    if (newTask.dueDate.microsecond == 555) {
      newTask.dueDate = dueDate;
    } else {
      final DateTime temp = newTask.dueDate;
      newTask.dueDate = DateTime(
          dueDate.year, dueDate.month, dueDate.day, temp.hour, temp.minute);
    }
    notifyListeners();
  }

  void updateTaskDueTime(TimeOfDay dueTime) {
    if (newTask.dueDate.year == 0) {
      newTask.dueDate = DateTime(0, 0, 0, dueTime.hour, dueTime.minute);
    } else {
      final DateTime temp = newTask.dueDate;
      newTask.dueDate = DateTime(
          temp.year, temp.month, temp.day, dueTime.hour, dueTime.minute);
    }
    notifyListeners();
  }

  void addTaskCreateDate(DateTime createDate) {
    newTask.createDate = createDate;
  }

这是我的编辑底部Sheet

  TaskEditBottomSheet({
    Key key,
    this.isUpdate,
    this.task,
  }) : super(key: key);

  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();

  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider(
      create: (context) => TaskEditState(newTask: task),
      builder: (context, child) {
        final TaskEditState taskEditState = Provider.of<TaskEditState>(context);
        final TaskService taskService = Provider.of<TaskService>(context);
        print(taskEditState.newTask.project.projectName);
        return Container(
            margin: EdgeInsets.all(20),
            child: Column(mainAxisSize: MainAxisSize.min, children: [
              TextFormField(
                validator: (value) {
                  if (value == null || value.isEmpty) {
                    return 'Please Enter Project Name';
                  }
                  return null;
                },
                decoration: InputDecoration(
                    hintText: taskEditState.newTask.taskName.isEmpty
                        ? 'Enter Task Name'
                        : taskEditState.newTask.taskName),
                textAlign: TextAlign.center,
                onChanged: (newText) {
                  taskEditState.updateTaskName(newText);
                },
              ),
              ProjectPicker(
                saveProject: taskEditState.updateTaskProject,
                child: ListTile(
                  leading: Icon(
                    Icons.circle,
                    color: Color(taskEditState.newTask.project.projectColor),
                  ),
                  title: Text(
                      taskEditState.newTask.project.projectName.isEmpty
                          ? 'Add Project'
                          : taskEditState.newTask.project.projectName,
                      style: Theme.of(context).textTheme.subtitle1),
                  trailing: Icon(Icons.arrow_drop_down_rounded,
                      color: Theme.of(context).unselectedWidgetColor),
                ),
              ),
              StatusPicker(saveStatus: taskEditState.updateTaskStatus),
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceAround,
                children: [
                  Text('Due: ', style: Theme.of(context).textTheme.subtitle1),
                  OutlinedButton.icon(
                    onPressed: () => DateAndTimePickers().selectDate(
                        context: context,
                        initialDate: taskEditState.newTask.dueDate.year == 1
                            ? DateTime.now()
                            : taskEditState.newTask.dueDate,
                        saveDate: taskEditState.updateTaskDueDate),
                    icon: Icon(Icons.today_rounded),
                    label: Text(taskEditState.newTask.dueDate.year == 1
                        ? 'Add Due Date'
                        : DateTimeFunctions().dateTimeToTextDate(
                            date: taskEditState.newTask.dueDate)),
                  ),
                  OutlinedButton.icon(
                    onPressed: () => DateAndTimePickers().selectTime(
                        context: context,
                        initialTime:
                            taskEditState.newTask.dueDate.microsecond == 555
                                ? TimeOfDay.now()
                                : TimeOfDay.fromDateTime(
                                    taskEditState.newTask.dueDate),
                        saveTime: taskEditState.updateTaskDueTime),
                    icon: Icon(Icons.alarm_rounded),
                    label: Text(taskEditState.newTask.dueDate.microsecond != 555
                        ? DateTimeFunctions().dateTimeToTextTime(
                            date: taskEditState.newTask.dueDate,
                            context: context)
                        : 'Add Due Time'),
                  ),
                ],
              ),
              Container(
                padding: EdgeInsets.symmetric(vertical: 20),
                child:
                    ElevatedButton.icon(
                  icon: Icon(Icons.check_circle_outline_rounded),
                  label: Text(isUpdate ? 'Update' : 'Add'),
                  onPressed: () {
                    if (_formKey.currentState.validate()) {
                      isUpdate
                          ? taskService.updateTask(
                              taskID: task.taskID,
                              updateData: taskEditState.newTask.toFirestore())
                          : taskService.addTask(
                              addData: taskEditState.newTask.toFirestore());
                      Navigator.pop(context);
                    }
                  },
                ),
              )
            ]));
      },
    );
  }
}

最后，这是调用底部的函数 sheet:

class EditBottomSheet {
  Future<dynamic> buildEditBottomSheet(
      {BuildContext context, Widget bottomSheet}) {
    return showModalBottomSheet(
        context: context,
        enableDrag: true,
        // isDismissible: false,
        isScrollControlled:
            true, // Allows the modal to me dynamic and keeps the menu above the keyboard
        shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.only(
                topLeft: Radius.circular(25), topRight: Radius.circular(25))),
        builder: (BuildContext context) {
          return bottomSheet;
        });
  }
}

非常感谢任何帮助，谢谢！

Answer 1

我发现了我的问题。我不确定这是否是 Dart 和我使用过的其他东西之间的语言差异。在 Provider State 字段中，我将新任务设置为等于旧任务：

TaskEditState({newTask}) : newTask = newTask as Task ?? Task();

我了解到这是将新任务设置为等于旧任务的引用。因此，当我更改有关新任务的任何内容时，它也会更新旧任务。我猜这是因为它们实际上是同一个对象，而新任务是旧任务的副本。因此，我为所有复制原始任务和 return 副本的模型创建了一个模型函数。这完全解决了我的问题。这是更新后的提供商状态文件：

TaskEditState({this.oldTask}) {
    if (oldTask != null) {
      newTask = oldTask.copyTask();
    } else {
      newTask = Task();
    }
  }

这是我的复制功能：

Task copyTask() {
    return Task(
        id: id ?? '',
        taskName: taskName ?? '',
        project: project ?? Project(),
        status: status ?? Status(),
        dueDate: dueDate ?? DateTime(0001, 01, 01, 0, 0, 0, 0, 555),
        createDate: createDate ?? DateTime.now());
  }

Flutter：从对象编辑新对象不正确地更改旧对象

Flutter: edit new object from object incorrectly changing old object

firebase

flutter

google-cloud-firestore

flutter-provider

flutter-showmodalbottomsheet