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MVVM Design Pattern in Flutter
Flutter is a cross-platform framework that allows you to write iOS and Android apps using a single codebase.
By default, Flutter apps don’t use any specific design pattern. This means the developer is in charge of choosing and implementing a pattern that fits their needs. The declarative nature of Flutter makes it an ideal candidate for the MVVM design pattern.
Understanding MVVM
MVVM stands for Model-View-ViewModel. The basic idea is to create a view model that’ll provide data to the view. The view can use the data provided by the view model to populate itself. Creating a view-model layer allows you to write modular code, which can be used by several views.
The MVVM design pattern originated from Microsoft. MVVM was heavily used in writing Windows Presentation Foundation (WPF) applications. The MVVM pattern is a fancy name for the PresentationModel.
Since design patterns are platform-agnostic, it can be used with any framework, including Flutter.
In this piece, we’ll create a movies app, which will fetch the movies based on an entered keyword and display them to the user. This app will be created based on the MVVM principles. Before diving into the code, check out the animation below to get an idea of the app we’ll be building.
Movies app
Implementing the web service
We’ll be using the OMDb API to fetch the movies. Make sure you register on their website to obtain an API key. Without a valid API key, you won’t be able to perform a successful request.
Now that you’ve registered with the OMDb service and have received your key, we can move on to implementing the web service/client. The web service uses the HTTP package to make a network request and to download the JSON response, but feel free to use any networking package you want.
After JSON has been download, it’s fed to the movie model to get a list of movie objects, as shown below:
import 'package:movies_app/models/movie.dart';
import 'package:http/http.dart' as http;
class Webservice {
Future<List<Movie>> fetchMovies(String keyword) async {
final url = "http://www.omdbapi.com/?s=$keyword&apikey=YOURAPIKEYHERE";
final response = await http.get(url);
if(response.statusCode == 200) {
final body = jsonDecode(response.body);
final Iterable json = body["Search"];
return json.map((movie) => Movie.fromJson(movie)).toList();
} else {
throw Exception("Unable to perform request!");
}
}
}
The movie model is implemented below:
class Movie {
final String title;
final String poster;
Movie({this.title, this.poster});
factory Movie.fromJson(Map<String, dynamic> json) {
return Movie(
title: json["Title"],
poster: json["Poster"]
);
}
}
Movie simply consists of a title and a poster. It also exposes a fromJson function, which allows us to create a Movie object based on the JSON response.
We used the term model to define our Movie objects, but, in reality, they’re serving the purpose of data transfer objects (DTO).
At this point, we have all the required data, and the next step is to display it on the screen. Before moving to the user interface, we must create view models that’ll be responsible for providing the data to the view.
Implementing view models
Although you can achieve the desired result by creating a single view model, we’ll create two separate view models in our application.
One view model, MoviesListViewModel, will represent the entire screen of displaying the movies. The second view model, MovieViewModel, will represent an individual movie — which will be displayed in the view.
The implementation of the view models is shown below:
class MovieListViewModel extends ChangeNotifier {
List<MovieViewModel> movies = List<MovieViewModel>();
Future<void> fetchMovies(String keyword) async {
// TODO
}
}
class MovieViewModel {
final Movie movie;
MovieViewModel({this.movie});
String get title {
return this.movie.title;
}
String get poster {
return this.movie.poster;
}
}
The MovieListViewModel consists of the movies property, which is going to return a list of MovieViewModel objects. The MovieViewModel takes in a Movie object and returns the title and poster as readonly properties. The next step is to fetch movies using the web service.
Setting up ChangeNotifier and ChangeNotifierProvider
The fetchMovies method in MovieListViewModel is responsible for retrieving the movies from the OMDb API using the help of the web service.
The implementation is shown below:
class MovieListViewModel extends ChangeNotifier {
List<MovieViewModel> movies = List<MovieViewModel>();
Future<void> fetchMovies(String keyword) async {
final results = await Webservice().fetchMovies(keyword);
this.movies = results.map((item) => MovieViewModel(movie: item)).toList();
print(this.movies);
notifyListeners();
}
}
We have updated our MovieListViewModel to inherit from ChangeNotifier. ChangeNotifier allows us to publish change notifications, which can be used by the view to update itself.
After we fetch the movies using the web service, we call the notifyListeners function, notifying all the subscribers/listeners. At present, there is no one listening, so no one is notified the movies have been downloaded.
In order to notify the view with the updated MovieListViewModel, we’ll have to use the ChangeNotifierProvider, which ispart of the Provider package. Add the provider package by adding the dependency in the pubspec.yaml file, as shown below:
dependencies:
flutter:
sdk: flutter
# The following adds the Cupertino Icons font to your application.
# Use with the CupertinoIcons class for iOS style icons.
cupertino_icons: ^0.1.2
http: ^0.12.0+2
provider: ^3.2.0
Next, we need to find a good place to inject the value from the provider. The value we’re talking about is an instance of MovieListViewModel since it extends ChangeNotifier and publishes notifications to the listeners.
In our case, we can use the main.dart file and inject the value to the MovieListPage. This means the MovieListViewModel will be available to MovieListPage and all of its children.
void main() => runApp(App());
class App extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: "Movies",
home:
ChangeNotifierProvider(
create: (context) => MovieListViewModel(),
child: MovieListPage(),
)
);
}
}
Awesome. The final step is to display the data on the screen. This is covered in the next section.
Displaying movies
For our app, we’ll ask the user to input the keyword and press return key on the keyboard. This will call the fetchMovies method on the MovieListViewModel, as shown below:
Container(
padding: EdgeInsets.only(left: 10),
decoration: BoxDecoration(
color: Colors.grey,
borderRadius: BorderRadius.circular(10)
),
child: TextField(
controller: _controller,
onSubmitted: (value) {
if(value.isNotEmpty) {
vm.fetchMovies(value);
_controller.clear();
}
},
fetchMovies will fetch all the movies based on the keyword and trigger notifyListeners. In order to get an updated instance of MovieListViewModel, we’ll get help from the provider package, as shown below:
@override Widget build(BuildContext context) {
final vm = Provider.of<MovieListViewModel>(context);
By adding the Provider inside the build method, we ensure whenever notifyListener is fired, we have access to the instance of MovieListViewModel.
Now if you run your app, it’ll fetch the movies based on the keyword and display them on the user interface.
If you want to perform an initial fetch when the page is loaded, then you can update your StatelessWidget to StatefulWidget and call fetchMovies from inside the initState method, as shown below:
class _MovieListPageState extends State<MovieListPage> {
final TextEditingController _controller = TextEditingController();
@override
void initState() {
super.initState();
// you can uncomment this to get all batman movies when the page is loaded
Provider.of<MovieListViewModel>(context, listen: false).fetchMovies("batman");
}
Note that we’re passing listen: false for the Provider, which means this is a one-time call only, and the changes won’t be tracked by the Provider.
View the GitHub repo here.
Thanks for reading!
#flutter #ios #programming
What is GEEK
Buddha Community
1597014000
Google's Flutter 1.20 stable announced with new features - Navoki
Flutter Google cross-platform UI framework has released a new version 1.20 stable.
Flutter is Google’s UI framework to make apps for Android, iOS, Web, Windows, Mac, Linux, and Fuchsia OS. Since the last 2 years, the flutter Framework has already achieved popularity among mobile developers to develop Android and iOS apps. In the last few releases, Flutter also added the support of making web applications and desktop applications.
Last month they introduced the support of the Linux desktop app that can be distributed through Canonical Snap Store(Snapcraft), this enables the developers to publish there Linux desktop app for their users and publish on Snap Store. If you want to learn how to Publish Flutter Desktop app in Snap Store that here is the tutorial.
Flutter 1.20 Framework is built on Google’s made Dart programming language that is a cross-platform language providing native performance, new UI widgets, and other more features for the developer usage.
Here are the few key points of this release:
Performance improvements for Flutter and Dart
In this release, they have got multiple performance improvements in the Dart language itself. A new improvement is to reduce the app size in the release versions of the app. Another performance improvement is to reduce junk in the display of app animation by using the warm-up phase.
If your app is junk information during the first run then the Skia Shading Language shader provides for pre-compilation as part of your app’s build. This can speed it up by more than 2x.
Added a better support of mouse cursors for web and desktop flutter app,. Now many widgets will show cursor on top of them or you can specify the type of supported cursor you want.
Autofill for mobile text fields
Autofill was already supported in native applications now its been added to the Flutter SDK. Now prefilled information stored by your OS can be used for autofill in the application. This feature will be available soon on the flutter web.
A new widget for interaction
InteractiveViewer is a new widget design for common interactions in your app like pan, zoom drag and drop for resizing the widget. Informations on this you can check more on this API documentation where you can try this widget on the DartPad. In this release, drag-drop has more features added like you can know precisely where the drop happened and get the position.
Updated Material Slider, RangeSlider, TimePicker, and DatePicker
In this new release, there are many pre-existing widgets that were updated to match the latest material guidelines, these updates include better interaction with Slider and RangeSlider, DatePicker with support for date range and time picker with the new style.
New pubspec.yaml format
Other than these widget updates there is some update within the project also like in pubspec.yaml file format. If you are a flutter plugin publisher then your old pubspec.yaml is no longer supported to publish a plugin as the older format does not specify for which platform plugin you are making. All existing plugin will continue to work with flutter apps but you should make a plugin update as soon as possible.
Preview of embedded Dart DevTools in Visual Studio Code
Visual Studio code flutter extension got an update in this release. You get a preview of new features where you can analyze that Dev tools in your coding workspace. Enable this feature in your vs code by _dart.previewEmbeddedDevTools_setting. Dart DevTools menu you can choose your favorite page embed on your code workspace.
Network tracking
The updated the Dev tools comes with the network page that enables network profiling. You can track the timings and other information like status and content type of your** network calls** within your app. You can also monitor gRPC traffic.
Generate type-safe platform channels for platform interop
Pigeon is a command-line tool that will generate types of safe platform channels without adding additional dependencies. With this instead of manually matching method strings on platform channel and serializing arguments, you can invoke native class and pass nonprimitive data objects by directly calling the Dartmethod.
There is still a long list of updates in the new version of Flutter 1.2 that we cannot cover in this blog. You can get more details you can visit the official site to know more. Also, you can subscribe to the Navoki newsletter to get updates on these features and upcoming new updates and lessons. In upcoming new versions, we might see more new features and improvements.
You can get more free Flutter tutorials you can follow these courses:
- Setup Flutter Desktop on Windows, Linux, MacOS using VSCode and Build – Flutter Tutorial
- Flutter Desktop Linux app | Build and Publish on Snapcraft Store
- Firebase Local Emulator Suite in Flutter
#dart #developers #flutter #app developed #dart devtools in visual studio code #firebase local emulator suite in flutter #flutter autofill #flutter date picker #flutter desktop linux app build and publish on snapcraft store #flutter pigeon #flutter range slider #flutter slider #flutter time picker #flutter tutorial #flutter widget #google flutter #linux #navoki #pubspec format #setup flutter desktop on windows
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What is Flutter and why you should learn it?
Flutter is an open-source UI toolkit for mobile developers, so they can use it to build native-looking** Android and iOS** applications from the same code base for both platforms. Flutter is also working to make Flutter apps for Web, PWA (progressive Web-App) and Desktop platform (Windows,macOS,Linux).
Flutter was officially released in December 2018. Since then, it has gone a much stronger flutter community.
There has been much increase in flutter developers, flutter packages, youtube tutorials, blogs, flutter examples apps, official and private events, and more. Flutter is now on top software repos based and trending on GitHub.
Flutter meaning?
What is Flutter? this question comes to many new developer’s mind.
Flutter means flying wings quickly, and lightly but obviously, this doesn’t apply in our SDK.
So Flutter was one of the companies that were acquired by **Google **for around $40 million. That company was based on providing gesture detection and recognition from a standard webcam. But later when the Flutter was going to release in alpha version for developer it’s name was Sky, but since Google already owned Flutter name, so they rename it to Flutter.
Where Flutter is used?
Flutter is used in many startup companies nowadays, and even some MNCs are also adopting Flutter as a mobile development framework. Many top famous companies are using their apps in Flutter. Some of them here are
Dream11
NuBank
Reflectly app
Abbey Road Studios
and many more other apps. Mobile development companies also adopted Flutter as a service for their clients. Even I was one of them who developed flutter apps as a freelancer and later as an IT company for mobile apps.
#dart #flutter #uncategorized #flutter framework #flutter jobs #flutter language #flutter meaning #flutter meaning in hindi #google flutter #how does flutter work #what is flutter
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Builder Design Pattern
What is Builder Design Pattern ? Why we should care about it ?
Starting from **Creational Design Pattern, **so wikipedia says “creational design pattern are design pattern that deals with object creation mechanism, trying to create objects in manner that is suitable to the situation”.
The basic form of object creations could result in design problems and result in complex design problems, so to overcome this problem Creational Design Pattern somehow allows you to create the object.
Builder is one of the** Creational Design Pattern**.
When to consider the Builder Design Pattern ?
Builder is useful when you need to do lot of things to build an Object. Let’s imagine DOM (Document Object Model), so if we need to create the DOM, We could have to do lot of things, appending plenty of nodes and attaching attributes to them. We could also imagine about the huge XML Object creation where we will have to do lot of work to create the Object. A Factory is used basically when we could create the entire object in one shot.
As **Joshua Bloch (**He led the Design of the many library Java Collections Framework and many more) – “Builder Pattern is good choice when designing the class whose constructor or static factories would have more than handful of parameters”
#java #builder #builder pattern #creational design pattern #design pattern #factory pattern #java design pattern
1591643580
Adobe XD plugin for Flutter with CodePen Tutorial
Recently Adobe XD releases a new version of the plugin that you can use to export designs directly into flutter widgets or screens. Yes, you read it right, now you can make and export your favorite design in Adobe XD and export all the design in the widget form or as a full-screen design, this can save you a lot of time required in designing.
What we will do?
I will make a simple design of a dialogue box with a card design with text over it as shown below. After you complete this exercise you can experiment with the UI. You can make your own components or import UI kits available with the Adobe XD.
#developers #flutter #adobe xd design export to flutter #adobe xd flutter code #adobe xd flutter code generator - plugin #adobe xd flutter plugin #adobe xd flutter plugin tutorial #adobe xd plugins #adobe xd to flutter #adobe xd tutorial #codepen for flutter.
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The Ultimate Guide To Tik Tok Clone App With Firebase - Ep 2
The Ultimate Guide To Tik Tok Clone App With Firebase - Ep 2
In this video, I'm going to show you how to make a Cool Tik Tok App a new Instagram using Flutter,firebase and visual studio code.
In this tutorial, you will learn how to Upload a Profile Pic to Firestore Data Storage.
🚀 Nice, clean and modern TikTok Clone #App #UI made in #Flutter⚠️
Starter Project : https://github.com/Punithraaj/Flutter_Tik_Tok_Clone_App/tree/Episode1
► Timestamps
0:00 Intro 0:20
Upload Profile Screen
16:35 Image Picker
20:06 Image Cropper
24:25 Firestore Data Storage Configuration.
⚠️ IMPORTANT: If you want to learn, I strongly advise you to watch the video at a slow speed and try to follow the code and understand what is done, without having to copy the code, and then download it from GitHub.
► Social Media
GitHub: https://github.com/Punithraaj/Flutter_Tik_Tok_Clone_App.git
LinkedIn: https://www.linkedin.com/in/roaring-r...
Twitter: https://twitter.com/roaringraaj
Facebook: https://www.facebook.com/flutterdartacademy
► Previous Episode : https://youtu.be/QnL3fr-XpC4
► Playlist: https://youtube.com/playlist?list=PL6vcAuTKAaYe_9KQRsxTsFFSx78g1OluK
I hope you liked it, and don't forget to like,comment, subscribe, share this video with your friends, and star the repository on GitHub!
⭐️ Thanks for watching the video and for more updates don't forget to click on the notification.
⭐️Please comment your suggestion for my improvement.
⭐️Remember to like, subscribe, share this video, and star the repo on Github :)
Hope you enjoyed this video!
If you loved it, you can Buy me a coffee : https://www.buymeacoffee.com/roaringraaj
LIKE & SHARE & ACTIVATE THE BELL Thanks For Watching :-)
https://youtu.be/F_GgZVD4sDk
#flutter tutorial - tiktok clone with firebase #flutter challenge @tiktokclone #fluttertutorial firebase #flutter firebase #flutter pageview #morioh #flutter