带有Cloud Firestore投票应用程序的Flutter应用程序>>

Question

我正在开发一个应用，我想添加投票功能。我已遵循本教程https://codelabs.developers.google.com/codelabs/flutter-firebase/#8

但是，这样做确实很不错，因为它要成为投票应用程序，所以我无法让我的用户针对同一选项多次投票。我到处都在寻找解决方案，但找不到。我希望有人知道这样做的简单方法。这是我的代码：

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


class VotingPage extends StatefulWidget {
  @override
  _VotingPage createState() {
    return _VotingPage();
  }
}

class _VotingPage extends State<VotingPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Top 10 Företagen!')),
      body: _buildBody(context),
    );
  }

  Widget _buildBody(BuildContext context) {
    return StreamBuilder<QuerySnapshot>(
      stream: Firestore.instance.collection('poll').snapshots(),
      builder: (context, snapshot) {
        if (!snapshot.hasData) return LinearProgressIndicator();
        return _buildList(context, snapshot.data.documents);
      },
    );
  }

  Widget _buildList(BuildContext context, List<DocumentSnapshot> snapshot) {
    return ListView(
      padding: const EdgeInsets.only(top: 20.0),
      children: snapshot.map((data) => _buildListItem(context, data)).toList(),
    );
  }

  Widget _buildListItem(BuildContext context, DocumentSnapshot data) {
    final record = Record.fromSnapshot(data);

    return Padding(
      key: ValueKey(record.name),
      padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),
      child: Container(
        decoration: BoxDecoration(
          border: Border.all(color: Colors.grey),
          borderRadius: BorderRadius.circular(5.0),
        ),
        child: ListTile(
          title: Text(record.name),
          trailing: Text(record.votes.toString()),
    onTap: () => record.reference.updateData({'votes': FieldValue.increment(1)})
      ),
    )
    );
  }
}

class Record {
  final String name;
  final int votes;
  final DocumentReference reference;

  Record.fromMap(Map<String, dynamic> map, {this.reference})
      : assert(map['name'] != null),
        assert(map['votes'] != null),
        name = map['name'],
        votes = map['votes'];

  Record.fromSnapshot(DocumentSnapshot snapshot)
      : this.fromMap(snapshot.data, reference: snapshot.reference);

  @override
  String toString() => "Record<$name:$votes>";
}

我正在开发一个应用，我想添加投票功能。我已经按照本教程https://codelabs.developers.google.com/codelabs/flutter-firebase/#8进行了，但是对于...

Answer 1

@@ Ted Bosman，您能够解决此问题吗？