從querysnapshot中獲取每個ListtTile的檔案ID

所以目前我正在嘗試從我的 firebase 集合中檢索檔案 ID。但我只是找不到檢索資料的方法。

return ListView.builder(
      scrollDirection: Axis.vertical,
      shrinkWrap: true,
      itemCount: announcementList.length,
      itemBuilder: (context, index){
        return AnnouncementTile(announcementlist: announcementList[index]);
      },
    );

我正在使用 listview.builder

class AnnouncementTile extends StatelessWidget {

  final Announcement announcementlist;
  AnnouncementTile({ required this.announcementlist });

  @override
  Widget build(BuildContext context) {
    return Card(
      elevation: 8.0,
      margin: new EdgeInsets.symmetric(
          horizontal: 10.0, vertical: 6.0),
      child: Container(
        decoration: BoxDecoration(
            color: Color.fromRGBO(64, 75, 96, .5)),
        child: ListTile(
            onTap: () {
               // String id = announcementList[index].id;
            },
            contentPadding: EdgeInsets.symmetric(
                 horizontal: 10.0, vertical: 10.0
            ),
            title: Text(
              announcementlist.title.length > 15 ? '${announcementlist.title.substring (0,18)} ...' : announcementlist.title, // limit the words that will be displayed out on screen
              style: TextStyle(
                  color: Colors.white,
                  fontWeight: FontWeight.bold),
            ),
            // subtitle: Text("10.07.2020", style: TextStyle(color: Colors.white)),

            subtitle: Column(
              children: <Widget>[
                Align(
                  alignment: Alignment.centerLeft,
                    child: Padding(
                      padding: const EdgeInsets.fromLTRB(0.0,2.0,0.0,0.0),
                      child: Text(announcementlist.content.length > 20 ? '${announcementlist.content.substring (0,20)} ... ' : announcementlist.content), // limit the words that will be displayed out on screen
                    ),
                ),
                Row(
                  children: <Widget>[
                    Icon(Icons.linear_scale,
                        color: Colors.yellowAccent),
                    Text(announcementlist.dateTime,
                        style: TextStyle(color: Colors.white))
                  ],
                ),
              ],
            ),
            trailing: Icon(Icons.keyboard_arrow_right,
                color: Colors.white, size: 30.0)),
      ),
    );
  }
}

這是我的串列視圖設計

class DatabaseService {

  final String? uid;
  DatabaseService({ required this.uid});

  //specifically for collection group
  final Query<Map<String, dynamic>> getAnnouncement = FirebaseFirestore.instance.collectionGroup('announcementlist');

  //announcement list from snapshot
  List <Announcement> _announcementListFromSnapshot(QuerySnapshot snapshot){
    return snapshot.docs.map((doc){
      return Announcement(
          title: doc.get('title') ?? '',
          dateTime: doc.get('dateTime') ?? '',
          content: doc.get('content') ?? '',
          aType: doc.get('announcementType') ?? '',
          aLevel: doc.get('announcementLevel') ?? ''
      );
    }).toList();
  }

  // get announcements stream
  Stream<List <Announcement>> get announcementList {
    return getAnnouncement.snapshots()
        .map(_announcementListFromSnapshot);
  }
}

上面的代碼是我從firebase中檢索資料然后將其顯示在listtiles中然后顯示在listview.builder中的方法。我在網上搜索了資源，但找不到適合我方法的正確方法。

我想做的是從firebase檢索檔案ID并將其傳遞給gesturedetector ontap方法以在另一個頁面中顯示檔案的內容。

下面是我的資料庫

uj5u.com熱心網友回復：

向類添加id欄位Announcement

class Announcement{
 final String id;
 .... //Other fields.

 Announcement({required this.id, ...});
}

然后像這樣傳遞id：

  List <Announcement> _announcementListFromSnapshot(QuerySnapshot snapshot){
    return snapshot.docs.map((doc){
      return Announcement(
          id: doc.id,
          title: doc.get('title') ?? '',
          dateTime: doc.get('dateTime') ?? '',
          content: doc.get('content') ?? '',
          aType: doc.get('announcementType') ?? '',
          aLevel: doc.get('announcementLevel') ?? ''
      );
    }).toList();
  }

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