FutureBuilder和ListView.builder

Question

有人可以向我解释如何使用FutureBuilder内部的ListView.Builder中的itemCount。

目前，我的FirebaseCloud Store只有一个Document，而我的应用返回的是文档的无限列表，

我尝试使用final PressedState pressController = Get.put(PressedState ()); return MaterialButton( onPressed: () { pressController.changeStatus(); }, child: pressController.pressedBool ? Container(...) : Container(...)),

但是，得到错误：itemCount: snapshot.data.documents.length,

编辑，该文件只能显示一次，如果与UID相关的文件不止一个，则仅显示一次。

这是我的代码

Class 'DocumentSnapshot' has no instance getter 'documents'. Receiver: Instance of 'DocumentSnapshot' Tried calling: documents

Answer 1

您需要这样的长度。

itemCount: snapshot.data.data().length,

Answer 2

您必须这样做：

extern crate futures;
extern crate tokio;
extern crate websocket;

use websocket::Message;
use websocket::result::WebSocketError;
use websocket::{ClientBuilder, OwnedMessage};
use websocket::header::{Headers, Authorization, Basic};
use websocket::futures::{Future, Stream, Sink};
use tokio_core::reactor::Core;

const CONNECTION: &'static str = "wss://some.remote.host.example.org:443/";

let mut core = Core::new()?;
let client = ClientBuilder::new(CONNECTION)?
   .async_connect_secure(None)  
   .and_then(|(msg, _)| match msg {
       Some(OwnedMessage::Text(response_txt)) => Ok(response_txt),
       _ => Err(WebSocketError::ProtocolError(UNSUPPORTED_MSG_ERR)),
   });

let response_message = core.run(client)?;

由于您只检索一个文档，因此在执行以下操作：

itemCount : 1

由于文档ID始终是唯一的，因此以上内容将始终检索一个文档。

Answer 3

if (snapshot.hasData) {
                        print('okkk');
                        print(manuais.data()['nome']);
return Container(
                        padding: EdgeInsets.all(16),
                        child: ListView.builder(

                            itemCount: snapshot.data.documents.length,

                            itemBuilder: (context, index) {


                              DocumentSnapshot manuais = snapshot.data;

                              return Card(
                                color: Colors.grey[250],
                                child: Container(
                                  padding: EdgeInsets.all(10),
                                  child: Column(
                                    crossAxisAlignment:
                                        CrossAxisAlignment.start,
                                    children: <Widget>[
                                      new Image.asset(
                                        'Images/pdflogo.png',
                                        width: 32,
                                      ),
                                      Center(
                                        child: Text(
                                          (manuais.data()['nome'].toString()),
                                          maxLines: 1,
                                          overflow: TextOverflow.ellipsis,
                                          style: TextStyle(fontSize: 16),
                                        ),
                                      ),
                                      ButtonBar(
                                        children: <Widget>[
                                          FlatButton(
                                              child: const Text(
                                                  'Compartilhar / Download'),
                                              onPressed: () async {
                                                var request = await HttpClient()
                                                    .getUrl(Uri.parse(manuais
                                                        .data()['documento']));
                                                var response =
                                                    await request.close();
                                                Uint8List bytes =
                                                    await consolidateHttpClientResponseBytes(
                                                        response);
                                      await Share.file(
                                             'ESYS AMLOG',
                                           'Manual.pdf',
                                               bytes,
                                            'image/jpg') ...(all your brackets go here)
    
         }