flutter-基于选项卡主体中内容长度的选项卡名称中的动态字符串

Question

大家好，我正在尝试更新选项卡名称，其中包含在选项卡内容中的列表中的项目数。该列表在选项卡内容组件中获取。如何将列表长度变量传递给标题标题？

// PARENT WIDGET

    class EventsScreen extends StatefulWidget {
  const EventsScreen({Key? key}) : super(key: key);

  @override
  State<EventsScreen> createState() => _EventsScreenState();
}

class _EventsScreenState extends State<EventsScreen> {
  
  @override
  Widget build(BuildContext context) {
    return Parent(
      child: TabbedHeader(
        tabTitles: [
          'Žiadosti (HERE I WANT TO ADD LENGTH OF REQUESTS LIST)'
        ],
        title: 'Udalosti',
        tabContents: [
          EventRequestTab() // CHILD COMPONENT WITH LIST OF REQUESTS
        ],
      ),
    );
  }
}

// CHILD WIDGET WITH REQUESTS LIST

class EventRequestTab extends StatefulWidget {
  const EventRequestTab({Key? key, this.requests}) : super(key: key);

  @override
  State<EventRequestTab> createState() => _EventRequestState();
}

class _EventRequestState extends State<EventRequestTab> {
  late EventService _eventService;
  late List<EventRequest>? requests;

  @override
  void initState() {
    super.initState();
    _eventService = EventService();
    requests = // FETCHING LIST OF REQUESTS

  }
} ... build method etc ....

在Initstate中的儿童小部件中，我正在获取后来在ListView中显示的请求列表。但是我不知道如何将被提取列表的长度传递给TabTitles属性。 TabBedheader是我的Tabbar小部件的自定义包装器。

Answer 1

您可以通过eventRequestTab的状态类中获取的列表，通过将回调传递到EventRequestTab widtget中。
此回调将返回以其参数获取的列表，在eventsscreen中，Tab名称已更新，并使用列表的长度更新

此处，此处是您的代码的更新：

// PARENT WIDGET

class EventsScreen extends StatefulWidget {
  const EventsScreen({Key? key}) : super(key: key);

  @override
  State<EventsScreen> createState() => _EventsScreenState();
}

class _EventsScreenState extends State<EventsScreen> {
  int? lengthOfRequestList; 


  void updateTabName(List<EventRequest> listOfRequests) {
    setState(() {
      lengthOfRequestList = listOfRequests.length;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Parent(
      child: TabbedHeader(
        tabTitles: ['Žiadosti (${int == null ? '...' : int})'],
        title: 'Udalosti',
        tabContents: [
          EventRequestTab(
            onListFetched: updateTabName,
          ) // CHILD COMPONENT WITH LIST OF REQUESTS
        ],
      ),
    );
  }
}

// CHILD WIDGET WITH REQUESTS LIST

class EventRequestTab extends StatefulWidget {
  final Function(List<EventRequest> fetchedList) onListFetched; 
  const EventRequestTab({Key? key, required this.onListFetched}) : super(key: key); 

  @override
  State<EventRequestTab> createState() => _EventRequestState();
}

class _EventRequestState extends State<EventRequestTab> {
  late EventService _eventService;
  late List<EventRequest>? requests;

  @override
  void initState() {
    super.initState();
    _eventService = EventService();
    requests = // FETCHING LIST OF REQUESTS
        widget.onListFetched(requests); 
  }
}