ex15-9.md

15.9 Reading data from Cloud Firestore

Example: Add packages

flutter pub add firebase_core
flutter pub add cloud_firestore

Example: Firebase Essentials II

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'firebase_options.dart';

void main() async {
  await Firebase.initializeApp(
      options: DefaultFirebaseOptions.currentPlatform,
      );
  if (kDebugMode) {
    try {
      FirebaseFirestore.instance.useFirestoreEmulator('localhost', 8080);
    } catch (e) {
      // ignore: avoid_print
      print(e);
    }
  }
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Firestore Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Firestore Database: Read'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);
  final String title;
  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(
          // Here we take the value from the MyHomePage object that was created by
          // the App.build method, and use it to set our AppBar title.
          title: Text(widget.title),
        ),
        body: StreamBuilder<List<Team>>(
          builder: (context, snapshot) {
            if (snapshot.hasError) {
              return const Text('Unable to read Cloud Firestore');
            } else if (snapshot.hasData) {
              final dbteams = snapshot.data!;
              return ListView(children: dbteams.map(buildTeam).toList());
            } else {
              return const Center(
                child: CircularProgressIndicator(),
              );
            }
          },
          stream: readTeams(),
        ),
      );
  Widget buildTeam(Team team) => ListTile(
        leading: const CircleAvatar(child: Text('Prem')),
        title: Text(team.name),
        subtitle: Text(team.location),
      );
  Future createTeam({required String name, required String location}) async {
    // Write to the Cloud Firestore database
    final docTeam = FirebaseFirestore.instance.collection('Teams').doc();
    final teamJSON = {
      'name': name,
      'location': location,
    };
    // Create the document and write data
    await docTeam.set(teamJSON);
    // Add: import 'package:flutter/foundation.dart';
    // Production Debug statement
    if (kDebugMode) {
      print("Database Write!");
    }
  }

  Stream<List<Team>> readTeams() => FirebaseFirestore.instance
      .collection('teams')
      .snapshots()
      .map((snapshot) =>
          snapshot.docs.map((doc) => Team.fromJson(doc.data())).toList());
}

class Team {
  // String id;
  final String name;
  final String location;
  Team({
    // this.id = '',
    required this.name,
    required this.location,
  });
  Map<String, dynamic> toJson() => {
        // 'id': id,
        'name': name,
        'location': location,
      };
  static Team fromJson(Map<String, dynamic> json) => Team(
      // id: json['id'],
      name: json['name'],
      location: json['location']);
}

Example: Emulator

if (kDebugMode) {
 try {
     FirebaseFirestore.instance.useFirestoreEmulator('localhost', 8080);
    } catch (e) {  
 print(e);
 }
}