flutter-app/flutter_app/lib/main.dart

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

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Names',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() {
    return _MyHomePageState();
  }
}

class _MyHomePageState extends State<MyHomePage> {
  final db = Firestore.instance.collection('lots');

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Lot 1')),
      body: _buildBody(context, db),
    );
  }

  Widget _buildBody(BuildContext context, CollectionReference stallDB) {
    return StreamBuilder<QuerySnapshot>(
      stream: stallDB.snapshots(),
      builder: (context, snapshot) {
        if (!snapshot.hasData) return LinearProgressIndicator();

        return _buildList(context, snapshot.data.documents);
      },
    );
  }

  Widget _buildList(BuildContext context, List<DocumentSnapshot> snapshot) {
    return GridView.count(
      primary: false,
      padding: const EdgeInsets.all(60),
      crossAxisSpacing: 1.0,
      crossAxisCount: 2,
      children: snapshot.map((data) => _buildListItem(context, data)).toList(),
    );
  }

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

    return Card(
      key: ValueKey(record.stall),
      color: Colors.blue,

      child: Center(
        child: Column(
          children: [
            ListTile(
              title: Text("Stall " + record.stall.toString(),
                  style: TextStyle(fontWeight: FontWeight.w500)),
              subtitle: Text(record.open.toString()),
            ),
          ],),
      ),


    );
  }
}

class Record {
  final int stall;
  final int passID;
  final bool open;
  final bool handicap;
  final DocumentReference reference;

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



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

  @override
  String toString() => "Record<$stall>";
}