firebase - documentSnapshot.data()不会传递给构建器:Flutter

Question

我一直在尝试从/ users集合中获取文档数据，
但是问题是我声明了de builder之后:
这是FutureBuiulder的必需参数，数据未通过它，并且我得到data = null。
我究竟做错了什么？

future: FirebaseFirestore.instance
              .collection('users')
              .doc(uid)
              .get()
              .then((DocumentSnapshot documentSnapshot) {
            if (documentSnapshot.exists) {
              print('The Documents Exists');
              print(documentSnapshot.data());
            }
            else {
              print('The document Do not Exist');
            }
              } //here closes then((DocumentSnapshot documentSnapshot) {
              ),// here closesthen((DocumentSnapshot documentSnapshot)

我得到的文档正确无误，如下图所示
但是，数据不会在生成器之后传递:

builder: (context, documentSnapshot) {
              if (documentSnapshot.hasData) {
                print('The Documents Exists');
                print(documentSnapshot.data());
              }
              else {
                print('The document Do not Exist');
              }

编辑
这是我的完整代码:

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';

class NewHome extends StatefulWidget {
  @override
  _NewHomeState createState() => _NewHomeState();
}

class _NewHomeState extends State<NewHome> {
  FirebaseFirestore firestore = FirebaseFirestore.instance;
  FirebaseAuth auth = FirebaseAuth.instance;

  @override
  Widget build(BuildContext context) {
    final User user = auth.currentUser;
    final uid = user.uid;
    return new Scaffold(
        body: new Container(
            child: FutureBuilder(
                future: FirebaseFirestore.instance
                    .collection('users')
                    .doc('uid')
                    .get(),


                builder: (context, snapshot) {
                  DocumentSnapshot manuais =
                  snapshot.data;
                  if (snapshot.hasData) {
                    print('okkk');
                  }
                  else{
                    print('nopeeeee');
                  }

            return Container(
                      padding: EdgeInsets.all(16),
                      child: ListView.builder(
                          itemCount: snapshot.data.documents.length,
                          itemBuilder: (context, uid) {
                            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(
                                              (snapshot
                                                  .data()['nome']
                                                  .toString()),
                                              maxLines: 1,
                                              overflow: TextOverflow.ellipsis,
                                              style: TextStyle(fontSize: 16),
                                            ),
                                          ),
                                        ])));
                          }));
                })));
  }
}

Answer 1

不要将then与FutureBuilder一起使用
将您的async方法直接传递给future，然后只有它解析为快照，您才能访问hasData，hasError getters之类的不同状态。

FutureBuilder(
      future: FirebaseFirestore.instance
          .collection('users')
          .doc("UID")
          .get(),
      builder: (context, snapshot) {
        if(snapshot.hasData){
            /// documentSnapshot.data()
        }
        return Container();
      }
    );