firebase - 如何将我的数据库最近的帖子显示在顶部？

Question

我的数据库看起来像这样。

在我的应用程序中，它以随机顺序显示，但我希望最近添加的内容会显示在顶部。

我尝试按孩子订购，但它不起作用。

这是检索数据代码：

DatabaseReference playlistsRef = FirebaseDatabase.instance.reference().child("Playlists");
playlistsRef.once().then((DataSnapshot snap)
{
  var KEYSplaylists = snap.value.keys;
  var Dataplaylists = snap.value;

  playlistsList.clear();

  for (var individualkeyplaylists in KEYSplaylists) {
    Playlists playlists = new Playlists
      (
        Dataplaylists[individualkeyplaylists]['image'],
        //    DATA[individualkeyplaylists]['playlisturl'],
        //    DATA[individualkeyplaylists]['time'],
        Dataplaylists[individualkeyplaylists]['title'],
        Dataplaylists[individualkeyplaylists]['type'],
        //    DATA[individualkeyplaylists]['userid'],
        Dataplaylists[individualkeyplaylists]['tap'],
      );

    playlistsList.add(playlists);

    setState(() {
      print('Length: $playlistsList.length');
    });
  };
});

还有这里的列表视图构建器

 ListView.builder
 (
   itemCount:  playlistsList.length,
   itemBuilder: (_, index) {
     return PlaylistsUI(playlistsList[index].image, playlistsList[index].title, playlistsList[index].type, playlistsList[index].tap,);
   }
 )

标签： firebasefirebase-realtime-databaseflutter

Answer 1

尝试这个：

playlistsList.insert(0, playlists); // Instead of playlistsList.add(playlists);