cloud_firestore 0.17.0-1.0.nullsafety.2

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example/lib/main.dart

// Copyright 2020, the Chromium project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

// @dart=2.9

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

/// Requires that a Firestore emulator is running locally.
/// See https://firebase.flutter.dev/docs/firestore/usage#emulator-usage
bool USE_FIRESTORE_EMULATOR = false;

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  if (USE_FIRESTORE_EMULATOR) {
    FirebaseFirestore.instance.settings = const Settings(
        host: 'localhost:8080', sslEnabled: false, persistenceEnabled: false);
  }
  runApp(FirestoreExampleApp());
}

/// The entry point of the application.
///
/// Returns a [MaterialApp].
class FirestoreExampleApp extends StatelessWidget {
  /// Given a [Widget], wrap and return a [MaterialApp].
  MaterialApp withMaterialApp(Widget body) {
    return MaterialApp(
      title: 'Firestore Example App',
      theme: ThemeData.dark(),
      home: Scaffold(
        body: body,
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return withMaterialApp(Center(child: FilmList()));
  }
}

/// Holds all example app films
class FilmList extends StatefulWidget {
  @override
  _FilmListState createState() => _FilmListState();
}

class _FilmListState extends State<FilmList> {
  String _filterOrSort = 'sort_year';

  _FilmListState();

  @override
  Widget build(BuildContext context) {
    Query query =
        FirebaseFirestore.instance.collection('firestore-example-app');

    Future<void> _onActionSelected(String value) async {
      if (value == 'batch_reset_likes') {
        WriteBatch batch = FirebaseFirestore.instance.batch();

        await query.get().then((querySnapshot) async {
          querySnapshot.docs.forEach((document) {
            batch.update(document.reference, {'likes': 0});
          });

          await batch.commit();

          setState(() {
            _filterOrSort = 'sort_year';
          });
        });
      } else {
        setState(() {
          _filterOrSort = value;
        });
      }
    }

    switch (_filterOrSort) {
      case 'sort_year':

        /// Order by the production year. Set [descending] to [false] to reverse the order
        query = query.orderBy('year', descending: true);
        break;
      case 'sort_likes_desc':

        /// Order by the number of likes. Set [descending] to [false] to reverse the order
        query = query.orderBy('likes', descending: true);
        break;
      case 'sort_likes_asc':

        /// Order by the number of likes. Set [descending] to [false] to reverse the order
        query = query.orderBy('likes');
        break;
      case 'sort_score':

        /// Order by the score, and return only those which has one great than 90
        query = query.orderBy('score').where('score', isGreaterThan: 90);
        break;
      case 'filter_genre_scifi':

        /// Return the movies which have the following categories
        query = query.where('genre', arrayContainsAny: ['Sci-Fi']);
        break;
      case 'filter_genre_fantasy':

        /// Return the movies which have the following categories
        query = query.where('genre', arrayContainsAny: ['Fantasy']);
        break;
    }

    return Scaffold(
        appBar: AppBar(
          title: Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              const Text('Firestore Example: Movies'),

              // This is a example use for 'snapshots in sync'.
              // The view reflects the time of the last Firestore sync; which happens any time a field is updated.
              StreamBuilder(
                stream: FirebaseFirestore.instance.snapshotsInSync(),
                builder: (context, _) {
                  return Text(
                    'Latest Snapshot: ${DateTime.now()}',
                    style: Theme.of(context).textTheme.caption,
                  );
                },
              )
            ],
          ),
          actions: <Widget>[
            PopupMenuButton(
              onSelected: (String value) async {
                await _onActionSelected(value);
              },
              itemBuilder: (BuildContext context) {
                return [
                  const PopupMenuItem(
                    value: 'sort_year',
                    child: Text('Sort by Year'),
                  ),
                  const PopupMenuItem(
                    value: 'sort_score',
                    child: Text('Sort by Score'),
                  ),
                  const PopupMenuItem(
                    value: 'sort_likes_asc',
                    child: Text('Sort by Likes ascending'),
                  ),
                  const PopupMenuItem(
                    value: 'sort_likes_desc',
                    child: Text('Sort by Likes descending'),
                  ),
                  const PopupMenuItem(
                    value: 'filter_genre_fantasy',
                    child: Text('Filter genre Fantasy'),
                  ),
                  const PopupMenuItem(
                    value: 'filter_genre_scifi',
                    child: Text('Filter genre Sci-Fi'),
                  ),
                  const PopupMenuItem(
                    value: 'batch_reset_likes',
                    child: Text('Reset like counts (WriteBatch)'),
                  ),
                ];
              },
            ),
          ],
        ),
        body: StreamBuilder<QuerySnapshot>(
          stream: query.snapshots(),
          builder: (context, stream) {
            if (stream.connectionState == ConnectionState.waiting) {
              return const Center(child: CircularProgressIndicator());
            }

            if (stream.hasError) {
              return Center(child: Text(stream.error.toString()));
            }

            QuerySnapshot querySnapshot = stream.data;

            return ListView.builder(
              itemCount: querySnapshot.size,
              itemBuilder: (context, index) => Movie(querySnapshot.docs[index]),
            );
          },
        ));
  }
}

/// A single movie row.
class Movie extends StatelessWidget {
  /// Contains all snapshot data for a given movie.
  final DocumentSnapshot snapshot;

  /// Initialize a [Move] instance with a given [DocumentSnapshot].
  Movie(this.snapshot);

  /// Returns the [DocumentSnapshot] data as a a [Map].
  Map<String, dynamic> get movie {
    return snapshot.data();
  }

  /// Returns the movie poster.
  Widget get poster {
    return SizedBox(
      width: 100,
      child: Center(child: Image.network(movie['poster'])),
    );
  }

  /// Returns movie details.
  Widget get details {
    return Padding(
        padding: const EdgeInsets.only(left: 8, right: 8),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            title,
            metadata,
            genres,
            Likes(
              reference: snapshot.reference,
              currentLikes: movie['likes'],
            )
          ],
        ));
  }

  /// Return the movie title.
  Widget get title {
    return Text('${movie['title']} (${movie['year']})',
        style: const TextStyle(fontSize: 18, fontWeight: FontWeight.bold));
  }

  /// Returns metadata about the movie.
  Widget get metadata {
    return Padding(
        padding: const EdgeInsets.only(top: 8),
        child: Row(children: [
          Padding(
            padding: const EdgeInsets.only(right: 8),
            child: Text('Rated: ${movie['rated']}'),
          ),
          Text('Runtime: ${movie['runtime']}'),
        ]));
  }

  /// Returns a list of genre movie tags.
  List<Widget> genreItems() {
    List<Widget> items = <Widget>[];
    movie['genre'].forEach((genre) {
      items.add(Padding(
        padding: const EdgeInsets.only(right: 2),
        child: Chip(
            label: Text(genre, style: const TextStyle(color: Colors.white)),
            backgroundColor: Colors.lightBlue),
      ));
    });
    return items;
  }

  /// Returns all genres.
  Widget get genres {
    return Padding(
        padding: const EdgeInsets.only(top: 8),
        child: Wrap(children: genreItems()));
  }

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(bottom: 4, top: 4),
      child: Row(
        children: [poster, Flexible(child: details)],
      ),
    );
  }
}

/// Displays and manages the movie 'like' count.
class Likes extends StatefulWidget {
  /// The [DocumentReference] relating to the counter.
  final DocumentReference /*!*/ reference;

  /// The number of current likes (before manipulation).
  final num /*!*/ currentLikes;

  /// Constructs a new [Likes] instance with a given [DocumentReference] and
  /// current like count.
  Likes({Key key, this.reference, this.currentLikes}) : super(key: key);

  @override
  State<StatefulWidget> createState() {
    return _Likes();
  }
}

class _Likes extends State<Likes> {
  int /*!*/ _likes;

  Future<void> _onLike(int current) async {
    // Increment the 'like' count straight away to show feedback to the user.
    setState(() {
      _likes = current + 1;
    });

    try {
      // Return and set the updated 'likes' count from the transaction
      int newLikes = await FirebaseFirestore.instance
          .runTransaction<int>((transaction) async {
        DocumentSnapshot txSnapshot = await transaction.get(widget.reference);

        if (!txSnapshot.exists) {
          throw Exception('Document does not exist!');
        }

        int updatedLikes = (txSnapshot.data()['likes'] ?? 0) + 1;
        transaction.update(widget.reference, {'likes': updatedLikes});
        return updatedLikes;
      });

      // Update with the real count once the transaction has completed.
      setState(() {
        _likes = newLikes;
      });
    } catch (e, s) {
      //ignore: avoid_print
      print(s);
      //ignore: avoid_print
      print('Failed to update likes for document! $e');

      // If the transaction fails, revert back to the old count
      setState(() {
        _likes = current;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    int currentLikes = _likes ?? widget.currentLikes ?? 0;

    return Row(children: [
      IconButton(
          icon: const Icon(Icons.favorite),
          iconSize: 20,
          onPressed: () {
            _onLike(currentLikes);
          }),
      Text('$currentLikes likes'),
    ]);
  }
}