amplify_datastore 0.6.5

The Amplify Flutter DataStore category plugin, providing a queryable, on-device data store.

example/lib/main.dart

/*
 * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

library sample_app;

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

import 'package:amplify_datastore/amplify_datastore.dart';

// Uncomment the below line to enable online sync
// import 'package:amplify_api/amplify_api.dart';

import 'package:amplify_flutter/amplify_flutter.dart';
import 'package:flutter/services.dart';
import 'models/ModelProvider.dart';

part 'queries_display_widgets.dart';
part 'save_model_widgets.dart';
part 'event_display_widgets.dart';

void main() {
  runApp(MyApp());
}

final divider = VerticalDivider(
  color: Colors.white,
  width: 10,
);

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  List<Post> _posts = <Post>[];
  List<Comment> _comments = <Comment>[];
  List<Blog> _blogs = <Blog>[];
  List<String> _postStreamingData = <String>[];
  List<String> _blogStreamingData = <String>[];
  List<String> _commentStreamingData = <String>[];
  bool _isAmplifyConfigured = false;
  String _queriesToView = "Post"; //default view
  Blog? _selectedBlogForNewPost;
  Post? _selectedPostForNewComment;
  late Stream<SubscriptionEvent<Post>> postStream;
  late Stream<SubscriptionEvent<Blog>> blogStream;
  late Stream<SubscriptionEvent<Comment>> commentStream;
  late StreamSubscription hubSubscription;
  bool _listeningToHub = true;
  late AmplifyDataStore datastorePlugin;

  final _titleController = TextEditingController();
  final _ratingController = TextEditingController();
  final _nameController = TextEditingController();
  final _contentController = TextEditingController();
  ScrollController _postScrollController =
      ScrollController(initialScrollOffset: 50.0);
  ScrollController _blogScrollController =
      ScrollController(initialScrollOffset: 50.0);
  ScrollController _commentScrollController =
      ScrollController(initialScrollOffset: 50.0);

  @override
  void initState() {
    super.initState();
    initPlatformState();
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  Future<void> initPlatformState() async {
    try {
      datastorePlugin = AmplifyDataStore(
        modelProvider: ModelProvider.instance,
        errorHandler: ((error) =>
            {print("Custom ErrorHandler received: " + error.toString())}),
      );
      await Amplify.addPlugin(datastorePlugin);

      // Configure

      // Uncomment the below lines to enable online sync.
      // await Amplify.addPlugin(AmplifyAPI());
      // await Amplify.configure(amplifyconfig);

      // Remove this line when using the lines above for online sync
      await Amplify.configure("{}");
    } on AmplifyAlreadyConfiguredException {
      print(
          'Amplify was already configured. Looks like app restarted on android.');
    }
    listenToHub();

    Amplify.DataStore.observeQuery(
      Blog.classType,
    ).listen((QuerySnapshot<Blog> snapshot) {
      var count = snapshot.items.length;
      var now = DateTime.now().toIso8601String();
      bool status = snapshot.isSynced;
      print(
          '[Observe Query] Blog snapshot received with $count models, status: $status at $now');
      setState(() {
        _blogs = snapshot.items;
      });
    });

    Amplify.DataStore.observeQuery(
      Post.classType,
    ).listen((QuerySnapshot<Post> snapshot) {
      setState(() {
        _posts = snapshot.items;
      });
    });

    Amplify.DataStore.observeQuery(
      Comment.classType,
    ).listen((QuerySnapshot<Comment> snapshot) {
      setState(() {
        _comments = snapshot.items;
      });
    });

    // setup streams
    postStream = Amplify.DataStore.observe(Post.classType);
    postStream.listen((event) {
      _postStreamingData.add('Post: ' +
          (event.eventType.toString() == EventType.delete.toString()
              ? event.item.id
              : event.item.title) +
          ', of type: ' +
          event.eventType.toString());
    }).onError((error) => print(error));

    blogStream = Amplify.DataStore.observe(Blog.classType);
    blogStream.listen((event) {
      _blogStreamingData.add('Blog: ' +
          (event.eventType.toString() == EventType.delete.toString()
              ? event.item.id
              : event.item.name) +
          ', of type: ' +
          event.eventType.toString());
    }).onError((error) => print(error));

    commentStream = Amplify.DataStore.observe(Comment.classType);
    commentStream.listen((event) {
      _commentStreamingData.add('Comment: ' +
          (event.eventType.toString() == EventType.delete.toString()
              ? event.item.id
              : event.item.content) +
          ', of type: ' +
          event.eventType.toString());
    }).onError((error) => print(error));

    setState(() {
      _isAmplifyConfigured = true;
    });
  }

  void listenToHub() {
    setState(() {
      hubSubscription = Amplify.Hub.listen([HubChannel.DataStore], (msg) {
        if (msg is NetworkStatusEvent) {
          print('Network status message: $msg');
          return;
        }
        print(msg);
      });
      _listeningToHub = true;
    });
  }

  void stopListeningToHub() {
    hubSubscription.cancel();
    setState(() {
      _listeningToHub = false;
    });
  }

  savePost(String title, int rating, Blog associatedBlog) async {
    try {
      Post post = Post(
          title: title,
          rating: rating,
          created: TemporalDateTime.now(),
          blog: associatedBlog);
      await Amplify.DataStore.save(post);
    } catch (e) {
      print(e);
    }
  }

  saveBlog(String name) async {
    try {
      Blog blog = Blog(
        name: name,
      );
      await Amplify.DataStore.save(blog);
    } catch (e) {
      print(e);
    }
  }

  saveComment(String content, Post associatedPost) async {
    try {
      Comment comment = Comment(content: content, post: associatedPost);
      await Amplify.DataStore.save(comment);
    } catch (e) {
      print(e);
    }
  }

  deletePost(String id) async {
    try {
      _selectedPostForNewComment = null;
      await Amplify.DataStore.delete(
          Post(id: id, title: "", rating: 0, created: TemporalDateTime.now()));
    } catch (e) {
      print(e);
    }
  }

  deleteBlog(String id) async {
    try {
      _selectedBlogForNewPost = null;
      await Amplify.DataStore.delete(Blog(id: id, name: ""));
    } catch (e) {
      print(e);
    }
  }

  deleteComment(String id) async {
    try {
      await Amplify.DataStore.delete(Comment(id: id, content: ""));
    } catch (e) {
      print(e);
    }
  }

  @override
  Widget build(BuildContext context) {
    executeAfterBuild();
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          centerTitle: true,
          title: Text(
            'Best DataStore App Ever',
            textAlign: TextAlign.center,
          ),
          actions: <Widget>[
            Padding(
                padding: EdgeInsets.only(right: 20.0),
                child: GestureDetector(
                  onTap: () async {
                    await Amplify.DataStore.clear();
                  },
                  child: Icon(
                    Icons.clear,
                    semanticLabel: "Clear",
                    size: 24.0,
                  ),
                )),
          ],
        ),
        body: Column(
          children: <Widget>[
            Padding(padding: EdgeInsets.all(10.0)),

            // Row for saving blog
            addBlogWidget(_nameController, _isAmplifyConfigured, saveBlog),

            // Row for saving post
            addPostWidget(
                titleController: _titleController,
                ratingController: _ratingController,
                isAmplifyConfigured: _isAmplifyConfigured,
                allBlogs: _blogs,
                saveFn: savePost,
                app: this,
                defaultBlog: _selectedBlogForNewPost),

            // Row for saving comment
            addCommentWidget(_contentController, _isAmplifyConfigured,
                _selectedPostForNewComment, _posts, saveComment, this),

            Padding(padding: EdgeInsets.all(10.0)),

            // Row for query buttons
            displayQueryButtons(_isAmplifyConfigured, this),

            Padding(padding: EdgeInsets.all(5.0)),
            Text("Listen to DataStore Hub"),
            Switch(
              value: _listeningToHub,
              onChanged: (value) {
                if (_listeningToHub) {
                  stopListeningToHub();
                } else {
                  listenToHub();
                }
              },
              activeTrackColor: Colors.lightGreenAccent,
              activeColor: Colors.green,
            ),

            Padding(padding: EdgeInsets.all(5.0)),

            // Showing relevant queries
            if (_queriesToView == "Post")
              getWidgetToDisplayPost(_posts, deletePost, _blogs)
            else if (_queriesToView == "Blog")
              getWidgetToDisplayBlog(_blogs, deleteBlog)
            else if (_queriesToView == "Comment")
              getWidgetToDisplayComment(_comments, deleteComment, _posts),

            Text(_queriesToView + " Events",
                style: TextStyle(
                    fontWeight: FontWeight.bold,
                    color: Colors.black,
                    fontSize: 14)),

            Padding(padding: EdgeInsets.all(5.0)),
            if (_queriesToView == "Post")
              getWidgetToDisplayPostEvents(
                  _postScrollController, _postStreamingData, executeAfterBuild)
            else if (_queriesToView == "Blog")
              getWidgetToDisplayBlogEvents(
                  _blogScrollController, _blogStreamingData, executeAfterBuild)
            else if (_queriesToView == "Comment")
              getWidgetToDisplayCommentEvents(_commentScrollController,
                  _commentStreamingData, executeAfterBuild),
          ],
          // replace with any or all query results as needed
        ),
      ),
    );
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _ambiguate(WidgetsBinding.instance)
        ?.addPostFrameCallback((_) => executeAfterBuild());
  }

  Future<void> executeAfterBuild() async {
    // this code will get executed after the build method
    // because of the way async functions are scheduled

    Future.delayed(const Duration(milliseconds: 500), () {
      if (_postScrollController.hasClients)
        _postScrollController.animateTo(
            _postScrollController.position.maxScrollExtent,
            duration: Duration(milliseconds: 200),
            curve: Curves.easeOut);
      if (_blogScrollController.hasClients)
        _blogScrollController.animateTo(
            _blogScrollController.position.maxScrollExtent,
            duration: Duration(milliseconds: 200),
            curve: Curves.easeOut);
      if (_commentScrollController.hasClients)
        _commentScrollController.animateTo(
            _commentScrollController.position.maxScrollExtent,
            duration: Duration(milliseconds: 200),
            curve: Curves.easeOut);
    });
  }
}

// TODO(dnys1): Remove when Flutter SDK version is bumped.
/// Ambiguates [o] to be nullable to account for transitions of the Flutter
/// API from nullable to non-null getters on some APIs.
T? _ambiguate<T>(T o) => o;