firebase - 计算基于id抖动在firebase上创建的总任务

Question

我想使用flutter在firebase上计算创建的任务总数。有没有办法使用flutter做到这一点，我必须使用java和swift来完成此功能。这就是我存储任务的方式，它们是由Firebase(ID)生成的。

在实时数据库中完成

final tasksData = Provider.of<Tasks>(context);
    final tasks = tasksData.tasks;
    print(tasks.length); // total tasks

Future<void> fetchAndSetProducts() async {
const url = 'https://firebaselink.firebaseio.com/tasks.json';
try {
  final response = await http.get(url);
  final extractedData = json.decode(response.body) as Map<String, dynamic>;
  final List<TodoList> loadedTasks = [];
  extractedData.forEach((taskId, taskData) {
    loadedTasks.add(TodoList(
      id: taskId, 
      name: taskData['name'],
      description: taskData['description'],
      date: DateTime.parse(taskData['date']),
      filename: taskData['filename'],
      location: taskData['location'],
      isCompleted: taskData['isCompleted'],
      notes: taskData['notes'],
    ));
  });
  _tasks = loadedTasks;
  notifyListeners();
} catch (error) {
  print(error);
  throw (error);
}
}

     List<TodoList> _tasks = [];

  List<TodoList> get tasks {
    return [..._tasks];
  }

进一步的问题在“文本”小部件中显示 future

  Future<void> refreshTasks(BuildContext context) async {
await Provider.of<Tasks>(context,listen: false).totalCompletedTask();
  }

Text( refreshTasks.toString()) 

错误:
明白啦:
关闭:(BuildContext)=>将来

Answer 1

您可以遍历每个文档，并检查isCompleted是否为true，然后增加totalTrue变量的值，该变量将保存总的true计数。

以下方法将为您工作。

 getCount() async {
    int totalcount = 0;
    await FirebaseDatabase.instance
        .reference()
        .child("tasks")
        .once()
        .then((DataSnapshot snapshot) {
      Map<dynamic, dynamic> data = snapshot.value;
      data.forEach((key, value) {
        if (value['isCompleted']) {
          totalcount++;
        }
      });
    });

    print(totalcount);
  }

更新:

Future<int> fetchAndSetProducts() async {
  const url = 'https://firebaselink.firebaseio.com/tasks.json';
  try {
    int totalcount = 0;

    final response = await http.get(url);
    final extractedData = json.decode(response.body) as Map<String, dynamic>;
    extractedData.forEach((taskId, taskData) {
      if (taskData['isCompleted']) {
        totalcount++;
      }
    });
    print(totalcount);
    return totalcount;
  } catch (error) {
    print(error);
    throw (error);
  }
}