有没有办法将 SliverList 的子计数设置为 Firebase 集合长度？

Question

我的 FutureBuild 在我的 ListView 中，因此我无法访问文档长度。有什么办法吗？我想制作一个 PostsContainer 列表，我知道它有点乱，但我没有找到其他方法。

这是我的代码：

    Future getPosts() async {
      var firestore = FirebaseFirestore.instance;
      qn = await firestore.collection("Posts").get();
      qn.docs;
      count = qn.docs.length;
    }

    return Scaffold(
      backgroundColor: Colors.black,
      body: CustomScrollView(
        slivers: <Widget>[
          appBar,
          SliverList(
            delegate: SliverChildBuilderDelegate(
              (context, index) {
                return FutureBuilder(
                  future: getPosts(),
                  builder: (_, snapshot) {
                    if(snapshot.connectionState == ConnectionState.waiting) {
                      return Center(
                        child: Text('Loading', style: TextStyle(color: Colors.white),),
                      );
                    }
                    else {
                      return PostContainer(
                        post: Post(user: UserModel(
                            imageUrl: 'https://images.ctfassets.net/hrltx12pl8hq/7yQR5uJhwEkRfjwMFJ7bUK/dc52a0913e8ff8b5c276177890eb0129/offset_comp_772626-opt.jpg?fit=fill&w=800&h=300',
                            name: qn.docs[index].get('name'),
                          ),
                          caption: qn.docs[index].get('Text') != null ? qn.docs[index].get('Text') : null,
                          timeAgo: '0 min', 
                          imageUrl: qn.docs[index].get('img') != null ? qn.docs[index].get('img') : null, 
                          likes: 6345, 
                          comments: 15, 
                          shares: 18, 
                          views: 45
                          ),
                      );
                    }
                  }
                );
              },
              childCount: count,
            )
          )
        ],
      ),
    );```

Thanks in advance!

Answer 1

试试这个

Future getPosts() async {
      var firestore = FirebaseFirestore.instance;
      qn = await firestore.collection("Posts").get();
      qn.docs;
      count = qn.docs.length;
    }

    return Scaffold(
      backgroundColor: Colors.black,
      body: CustomScrollView(
        slivers: <Widget>[
          appBar,
          FutureBuilder(
              future: getPosts(),
              builder: (_, snapshot) {
                if(snapshot.connectionState == ConnectionState.waiting) {
                  return Center(
                    child: Text('Loading', style: TextStyle(color: Colors.white),),
                  );
                }
                else {
                  return SliverList(
                      delegate: SliverChildBuilderDelegate(
                            (context, index) {
                          return PostContainer(
                            post: Post(user: UserModel(
                              imageUrl: 'https://images.ctfassets.net/hrltx12pl8hq/7yQR5uJhwEkRfjwMFJ7bUK/dc52a0913e8ff8b5c276177890eb0129/offset_comp_772626-opt.jpg?fit=fill&w=800&h=300',
                              name: qn.docs[index].get('name'),
                            ),
                                caption: qn.docs[index].get('Text') != null ? qn.docs[index].get('Text') : null,
                                timeAgo: '0 min',
                                imageUrl: qn.docs[index].get('img') != null ? qn.docs[index].get('img') : null,
                                likes: 6345,
                                comments: 15,
                                shares: 18,
                                views: 45
                            ),
                          );
                        },
                        childCount: count,
                      )
                  );
                }
              }
          )
        ],
      ),
    );

您只是按错误的顺序包装了小部件。正确的是 Sliverlist 应该在 future builder

里面

Answer 2

我成功了！这是我的脚本。

    QuerySnapshot qn;

Future getPosts() async {
  var firestore = FirebaseFirestore.instance;
  qn = await firestore.collection("Posts").get();
  qn.docs;
}

return FutureBuilder(
  future: getPosts(),
  builder: (context, snapshot){
   Widget newsListSliver;
   if(snapshot.connectionState == ConnectionState.waiting) {
     newsListSliver = SliverToBoxAdapter(child: CircularProgressIndicator(),);
  } else {
     newsListSliver = SliverList(delegate: SliverChildBuilderDelegate((context, index) {
      return PostContainer(
        post: Post(
          user: UserModel(
            imageUrl: qn.docs[index].get('picture'),
            name: qn.docs[index].get('name'),
          ),
          caption: qn.docs[index].get('Caption') != null ? qn.docs[index].get('Caption') : null,
          text: qn.docs[index].get('Text') != null ? qn.docs[index].get('Text') : null,
          timeAgo: '0 min', 
          imageUrl: qn.docs[index].get('img') != null ? qn.docs[index].get('img') : null, 
          likes: 6345, 
          comments: 15, 
          shares: 18, 
          views: 45
        ),
      );
    }, childCount: qn.docs.length,)
  );  
}
return CustomScrollView(
  slivers: <Widget>[
    appBar,
    newsListSliver
  ],
);

}, );

有没有办法将 SliverList 的子计数设置为 Firebase 集合长度？

Is there a way to set the childcount of a SliverList to the Firebase Collection Length?

flutter

flutter-futurebuilder