Question

我有一个数组从JSON文件中获取数据。我能够将一组对象存储到我的Task[]中。现在我想按状态检索数据（'已提交'或'已解决'等）。我尝试了很多方法，但无法实现。请帮帮我。

data: [{
  taskname: 'Test1',
  taskId: '1',
  status: 'Submitted'
}, {
  taskname: 'Test2',
  taskId: '2',
  status: 'Resolved'
}, {
  taskname: 'Test3',
  taskId: '4',
  status: 'Submitted'
}, {
  taskname: 'Test4',
  taskId: '5',
  status: 'In Progress'
}, {
  taskname: 'Test5',
  taskId: '6',
  status: 'Resolved'
}, {
  taskname: 'Test6',
  taskId: '7',
  status: 'Submitted'
}
}]

Task.ts

export interface Task {
  taskId: any;
  taskname: any;
  status: any;
}

taskService.ts

getTask() {
  return this.http.get('../app/common/task.json')
    .toPromise()
    .then(res => < Task[] > res.json().data)
    .then(data => {
      return data;
    });

}

taskCompnent.ts

export class TaskComponent implements OnInit {
  taskList: Task[];
  datasource: Task[];
  sortedList: Task[];
  ngOnInit() {
    this.taskService.getTask().then(files => this.files = files);
    this.vecService.getData().then(taskList => {
      this.datasource = taskList;
      this.taskList = this.datasource; // Storing data into my task list array
    });
  }
}

这是我尝试按状态过滤的内容：

 this.sortedList = this.taskList.filter(
      task => task.status ==='Submitted');

显示错误低于错误：

无法读取未定义的属性“过滤器”

Answer 1

这是因为promises / HTTP请求是异步的。你需要在promises的回调中添加过滤器，如果你将它放在taskList之外将是未定义的，因此无法应用过滤器

this.vecService.getData().then(taskList => {
        this.datasource = taskList;
        this.taskList = this.datasource;// Storing data into my task list array
        this.sortedList = this.taskList.filter(
        task => task.status ==='Submitted');

    });

angular2 typescript数组的对象按值过滤

1 个答案: