Flutter Tutorial - Dio Connectivity Retry Interceptor

Performing HTTP requests is all fun and games until there’s no internet connection. Sure, you can display a sad error message or a “Chrome dinosaur” to the user, but wouldn’t it be better to take the initiative and automatically retry the request when the user connects to a WiFi network or enables mobile data? This is precisely what we’re going to implement in this tutorial.

Starter project

We’re going to use the dio HTTP client and the connectivity package to accomplish our goal. We’re _not _using the default http package because it’s pretty lame. I mean, come on! No support for interceptors?

All of the packages and the basic UI is prepared for you in the starter project so that you won’t waste time if you want to follow along.

Creating an interceptor

Interceptors run every time you do some action on a Dio object. You can then perform logic in three callback methods - onRequest, onResponse and onError.

They are useful for plenty of things such as logging or, in our case, scheduling a request retry when we detect there’s no connection. You are probably familiar with the dreaded SocketException that gets thrown when the device isn’t connected to a network. This means only one thing - we’re going to utilize the onError callback.

retry_interceptor.dart

class RetryOnConnectionChangeInterceptor extends Interceptor {
  @override
  Future onError(DioError err) async {
    // TODO: Schedule a retry
  }
}

This is the basic outline of our interceptor. We’re going to get to the retry logic in just a bit but first, it’s important to note that the onError callback will run for all kinds of errors including status codes such as 401 or 503. I think it’s a good idea to retry the request only when the error is the aforementioned SocketException.

How can we find out which exact type of of an error occurred? We can use the handy fields of the DioError object!

retry_interceptor.dart

@override
Future onError(DioError err) async {
  if (_shouldRetry(err)) {
    // TODO: Schedule a retry
  }
  // Let the error "pass through" if it's not the error we're looking for
  return err;
}

bool _shouldRetry(DioError err) {
  return err.type == DioErrorType.DEFAULT &&
      err.error != null &&
      err.error is SocketException;
}

Request retrier

Having the interceptor is only one part of the game. How can we actually schedule the failed requests to be retried as soon as the device is connected to a network? The answer is connectivity package, Stream and a Completer.

We could just plop this logic right into the RetryOnConnectionChangeInterceptor but I’m a proponent of keeping the code focused on one task. Let’s create a DioConnectivityRequestRetrier.

dio_connectivity_request_retrier.dart

class DioConnectivityRequestRetrier {
  final Dio dio;
  final Connectivity connectivity;

  DioConnectivityRequestRetrier({
    @required this.dio,
    @required this.connectivity,
  });

  Future<Response> scheduleRequestRetry(RequestOptions requestOptions) async {
    // TODO: Implement
  }
}

scheduleRequestRetry will be passed the failed RequestOptions object which will be used to perform the same request for the second time. We’re then going to return the successful Response back to the interceptor which scheduled a request retry.

To retry the request immediately when the network connection changes, the Connectivity class offers a handy Stream called onConnectivityChanged.

dio_connectivity_request_retrier.dart

Future<Response> scheduleRequestRetry(RequestOptions requestOptions) async {
  StreamSubscription streamSubscription;

  streamSubscription = connectivity.onConnectivityChanged.listen(
    (connectivityResult) async {
      // We're connected either to WiFi or mobile data
      if (connectivityResult != ConnectivityResult.none) {
        // Ensure that only one retry happens per connectivity change by cancelling the listener
        streamSubscription.cancel();
        // Copy & paste the failed request's data into the new request
        dio.request(
          requestOptions.path,
          cancelToken: requestOptions.cancelToken,
          data: requestOptions.data,
          onReceiveProgress: requestOptions.onReceiveProgress,
          onSendProgress: requestOptions.onSendProgress,
          queryParameters: requestOptions.queryParameters,
          options: requestOptions,
        );
      }
    },
  );
}

The connectivity package does not guarantee that the user is actually connected to the world-wide web. The user may just happen to use a WiFi network without any Internet access. That’s not a problem though as in that case, the retry will again fail with a SocketException which you can catch as usual.
You may have noticed something fishy going on in the code above. There’s no return **statement! **It’s not as simple as returning the result of calling dio.request() directly. After all, the request happens inside a closure of the listen method and we want to return the Response from the scheduleRequestRetry method.

This is just the right occasion to use a Completer. We can return its Future from the whole scheduleRequestRetry, which we will then complete from the closure.

dio_connectivity_request_retrier.dart

Future<Response> scheduleRequestRetry(RequestOptions requestOptions) async {
  StreamSubscription streamSubscription;
  final responseCompleter = Completer<Response>();

  streamSubscription = connectivity.onConnectivityChanged.listen(
    (connectivityResult) async {
      if (connectivityResult != ConnectivityResult.none) {
        streamSubscription.cancel();
        // Complete the completer instead of returning
        responseCompleter.complete(
          dio.request(
            requestOptions.path,
            cancelToken: requestOptions.cancelToken,
            data: requestOptions.data,
            onReceiveProgress: requestOptions.onReceiveProgress,
            onSendProgress: requestOptions.onSendProgress,
            queryParameters: requestOptions.queryParameters,
            options: requestOptions,
          ),
        );
      }
    },
  );

  return responseCompleter.future;
}

Putting it all together

With this retrier class in place, we can now plug it into the interceptor.

retry_interceptor.dart

class RetryOnConnectionChangeInterceptor extends Interceptor {
  final DioConnectivityRequestRetrier requestRetrier;

  RetryOnConnectionChangeInterceptor({
    @required this.requestRetrier,
  });

  @override
  Future onError(DioError err) async {
    if (_shouldRetry(err)) {
      try {
        return requestRetrier.scheduleRequestRetry(err.request);
      } catch (e) {
        // Let any new error from the retrier pass through
        return e;
      }
    }
    // Let the error pass through if it's not the error we're looking for
    return err;
  }

  bool _shouldRetry(DioError err) {
    return err.type == DioErrorType.DEFAULT &&
        err.error != null &&
        err.error is SocketException;
  }
}

The main.dart file from the starter project contains a working code to perform GET requests with Dio. All we need to do, is to plug the interceptor into it.
main.dart

class _HomePageState extends State<HomePage> {
  Dio dio;
  String firstPostTitle;
  bool isLoading;

  @override
  void initState() {
    super.initState();
    dio = Dio();
    firstPostTitle = 'Press the button 👇';
    isLoading = false;

    dio.interceptors.add(
      RetryOnConnectionChangeInterceptor(
        requestRetrier: DioConnectivityRequestRetrier(
          dio: dio,
          connectivity: Connectivity(),
        ),
      ),
    );
  }
  ...
}

And just like that, you now know how to retry requests automatically when device connection state changes. It’s going to create a much better user experience than just passively saying “no connection, retry by pressing a button”.

#flutter #mobileapps #webdev

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Flutter Tutorial - Dio Connectivity Retry Interceptor

Destiny Volkman

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.

sksl_warm-up

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.

flutter_autofill

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.

flutter_DatePicker

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:

#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

Terry Tremblay

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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-mobile-desktop-web-embedded_min

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.

humming_bird_dart_flutter

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.

Flutter as a service

#dart #flutter #uncategorized #flutter framework #flutter jobs #flutter language #flutter meaning #flutter meaning in hindi #google flutter #how does flutter work #what is flutter

Aliyah Satterfield

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.

Punith Raaj

1644991598

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

Punith Raaj

1640672627

Flutter Hotel Booking UI - Book your Stay At A New Hotel With Flutter - Ep1

https://youtu.be/-tHUmjIkGJ4
Flutter Hotel Booking UI - Book your Stay At A New Hotel With Flutter - Ep1
#flutter #fluttertravelapp #hotelbookingui #flutter ui design

In this video, I'm going to show you how to make a Cool Hotel Booking App using Flutter and visual studio code.

In this tutorial, you will learn how to create a Splash Screen and Introduction Screen, how to implement a SmoothPageIndicator in Flutter.

🚀 Nice, clean and modern Hotel Booking #App #UI made in #Flutter

⚠️ 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

LinkedIn: https://www.linkedin.com/in/roaring-r...

Twitter: https://twitter.com/roaringraaj

Facebook: https://www.facebook.com/flutterdartacademy

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

#flutter riverpod #flutter travel app #appointment app flutter #morioh

Flutter Tutorial - Dio Connectivity Retry Interceptor

Starter project

Creating an interceptor

Request retrier

Putting it all together

What is GEEK

Buddha Community

Google's Flutter 1.20 stable announced with new features - Navoki

Performance improvements for Flutter and Dart

Autofill for mobile text fields

Updated Material Slider, RangeSlider, TimePicker, and DatePicker

New pubspec.yaml format

Preview of embedded Dart DevTools in Visual Studio Code

Network tracking

Generate type-safe platform channels for platform interop

What is Flutter and why you should learn it?

Flutter meaning?

Where Flutter is used?

Dream11

NuBank

Reflectly app

Abbey Road Studios

Adobe XD plugin for Flutter with CodePen Tutorial

The Ultimate Guide To Tik Tok Clone App With Firebase - Ep 2

Flutter Hotel Booking UI - Book your Stay At A New Hotel With Flutter - Ep1

New `pubspec.yaml` format