firebase - Flutter需要更多时间从Firestore加载视频

Question

我正在构建一个flutter应用程序，该应用程序可以从Firestore存储中获取视频，但是加载所有视频都需要花费大量时间，并且每当我打开该应用程序时，它总是会下载视频。我想像tiktok一样构建该应用程序，它一次只能加载一个视频，而不是下载firestore数据库中存在的整个视频。以下是dart代码。

class Timeline extends StatefulWidget {
  final User currentUser;
  Timeline({this.currentUser});
  @override
  _TimelineState createState() => _TimelineState();
}
class _TimelineState extends State<Timeline> with AutomaticKeepAliveClientMixin{
  List<Post> posts;
  buildTimeline() {
        PreloadPageView.builder(
          scrollDirection: Axis.vertical,
          itemCount: posts.length,
          preloadPagesCount: 100000,
          itemBuilder: (BuildContext context, int index) {
            return
              Stack(
                children: <Widget>[
                  //AppVideoPlayer(mediaUrl: posts[index].mediaUrl), onScreenControls(posts[index])
                  posts[index],
                ],)
  void initState() {
    super.initState();
    getTimeline();
  }
  getTimeline() async {
    QuerySnapshot snapshot = await timelineRef
        .document(widget.currentUser.id)
        .collection('timelinePosts')
        .orderBy('timestamp', descending: true)
        .getDocuments();
    List<Post> posts =
    snapshot.documents.map((doc) => Post.fromDocument(doc)).toList();
    setState(() {
      this.posts = posts;
    });
  }
  @override
  Widget build(context) {
    return Scaffold(
        backgroundColor: Colors.black,
        //appBar: header(context, isAppTitle: true),
        body: RefreshIndicator(
            onRefresh: () => getTimeline(),
            child: buildTimeline()));
  }
}

class Post extends StatefulWidget {
  final String postId;
  final String ownerId;
  final String username;
  final String mediaUrl;
  Post({
    this.postId,
    this.ownerId,
    this.username,
    this.mediaUrl,
  });
  factory Post.fromDocument(DocumentSnapshot doc) {
    return Post(
      postId: doc['postId'],
      ownerId: doc['ownerId'],
      username: doc['username'],
      mediaUrl: doc['mediaUrl'],
    );
  }
  @override
  _PostState createState() => _PostState(
        postId: this.postId,
        ownerId: this.ownerId,
        username: this.username,
        mediaUrl: this.mediaUrl,
      );
}
class _PostState extends State<Post> {
  final String currentUserId = currentUser?.id;
  final String postId;
  final String ownerId;
  final String username;
  final String mediaUrl;
  _PostState({
    this.postId,
    this.ownerId,
    this.username,
    this.mediaUrl,
  });
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        Stack(
          children: <Widget>[
            AppVideoPlayer(mediaUrl: mediaUrl),
          ],
        ),
      ],
    );
  }

Answer 1

使用此代码，您基本上可以查询集合timelinePosts中用户widget.currentUser.id的所有文档。

    QuerySnapshot snapshot = await timelineRef
    .document(widget.currentUser.id)
    .collection('timelinePosts')
    .orderBy('timestamp', descending: true)
    .getDocuments();

尝试像这样获取所需的特定文档:

var document = await Firestore.instance.collection('COLLECTION_NAME').document('TESTID1');document.get() => then(function(document) {print(document('name'));}

为了提高性能，您可以预先下载视频并在用户实际需要使用它们之前对其进行缓存。