dart - 如何在Dart中删除重复项

Question

所以这是我设置数据的方式

  loadNotification(int limit, int offset) async {
    List<Notification> notif =
        await fetchNotification(http.Client(), limit, offset);
    tempNotification.addAll(notif);

    _notificationController.add(tempNotification);
  }

这是我的 Notification()

class Notification {
  final String notificationId;
  final String notificationTitle;
  final String notificationBody;
  final String notificationDate;
  final String notificationTo;
  final String notificationImage;

  Notification({
    this.notificationId,
    this.notificationTitle,
    this.notificationBody,
    this.notificationDate,
    this.notificationTo,
    this.notificationImage,
  });

  factory Notification.fromJson(Map<String, dynamic> json) {
    return Notification(
        notificationId: json['notificationId'] as String,
        notificationTitle: json['notificationTitle'] as String,
        notificationBody: json['notificationBody'] as String,
        notificationDate: json['notificationDate'] as String,
        notificationTo: json['notificationTo'] as String,
        notificationImage: json['notificationImage'] as String);
  }
}

因此，举个例子，我的第一个数据将显示1,2,3,4,5，然后单击“加载”，它将显示1,2,3,4,5,3,4,5,6,7。

我已经尝试将 loadNotification更改为此

  loadNotification(int limit, int offset) async {
    List<Notification> notif =
        await fetchNotification(http.Client(), limit, offset);
    tempNotification.addAll(notif);
    filteredNotification = tempNotification.toSet().toList();
    _notificationController.add(filteredNotification);
  }

但仍然没有帮助，我该如何实现？提前致谢

Answer 1

tempNotification.toSet().toList() 

不能按预期工作，因为必须重写Notification类的equals和hashCode，仅在这种情况下，您将按值进行比较，否则按ref进行比较。

一些基于notificationId的示例:

class Notification {
  final String notificationId;
  ...
  bool operator ==(o) => o is Notification && notificationId == o.notificationId;
  int get hashCode => notificationId.hashCode;
}