http_interceptor

Pub style: effective dart License: MIT codecov Star on GitHub

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This is a plugin that lets you intercept the different requests and responses from Dart's http package. You can use to add headers, modify query params, or print a log of the response.

Quick Reference

Already using http_interceptor? Check out the 1.0.0 migration guide for quick reference on the changes made and how to migrate your code.

Installation

Include the package with the latest version available in your pubspec.yaml.

http_interceptor: ^1.0.1

Features

  • 🚦 Intercept & change unstreamed requests and responses.
  • ✨ Retrying requests when an error occurs or when the response does not match the desired (useful for handling custom error responses).
  • πŸ‘“ GET requests with separated parameters.
  • ⚑️ Standard bodyBytes on ResponseData to encode or decode in the desired format.
  • πŸ™ŒπŸΌ Array parameters on requests.
  • πŸ–‹ Supports self-signed certificates (except on Flutter Web).
  • 🍦 Compatible with vanilla Dart projects or Flutter projects.
  • πŸŽ‰ Null-safety.

Usage

import 'package:http_interceptor/http_interceptor.dart';

Building your own interceptor

In order to implement http_interceptor you need to implement the InterceptorContract and create your own interceptor. This abstract class has two methods: interceptRequest, which triggers before the http request is called; and interceptResponse, which triggers after the request is called, it has a response attached to it which the corresponding to said request. You could use this to do logging, adding headers, error handling, or many other cool stuff. It is important to note that after you proccess the request/response objects you need to return them so that http can continue the execute.

  • Logging with interceptor:
class LoggingInterceptor implements InterceptorContract {
  @override
  Future<RequestData> interceptRequest({required RequestData data}) async {
    print(data.toString());
    return data;
  }

  @override
  Future<ResponseData> interceptResponse({required ResponseData data}) async {
      print(data.toString());
      return data;
  }

}
  • Changing headers with interceptor:
class WeatherApiInterceptor implements InterceptorContract {
  @override
  Future<RequestData> interceptRequest({required RequestData data}) async {
    try {
      data.params['appid'] = OPEN_WEATHER_API_KEY;
      data.params['units'] = 'metric';
      data.headers["Content-Type"] = "application/json";
    } catch (e) {
      print(e);
    }
    return data;
  }

  @override
  Future<ResponseData> interceptResponse({required ResponseData data}) async => data;
}

Using your interceptor

Now that you actually have your interceptor implemented, now you need to use it. There are two general ways in which you can use them: by using the InterceptedHttp to do separate connections for different requests or using a InterceptedClient for keeping a connection alive while making the different http calls. The ideal place to use them is in the service/provider class or the repository class (if you are not using services or providers); if you don't know about the repository pattern you can just google it and you'll know what I'm talking about. πŸ˜‰

Using interceptors with Client

Normally, this approach is taken because of its ability to be tested and mocked.

Here is an example with a repository using the InterceptedClient class.

class WeatherRepository {
  Client client = InterceptedClient.build(interceptors: [
      WeatherApiInterceptor(),
  ]);

  Future<Map<String, dynamic>> fetchCityWeather(int id) async {
    var parsedWeather;
    try {
      final response =
          await client.get("$baseUrl/weather".toUri(), params: {'id': "$id"});
      if (response.statusCode == 200) {
        parsedWeather = json.decode(response.body);
      } else {
        throw Exception("Error while fetching. \n ${response.body}");
      }
    } catch (e) {
      print(e);
    }
    return parsedWeather;
  }

}

Using interceptors without Client

This is mostly the straight forward approach for a one-and-only call that you might need intercepted.

Here is an example with a repository using the InterceptedHttp class.

class WeatherRepository {

    Future<Map<String, dynamic>> fetchCityWeather(int id) async {
    var parsedWeather;
    try {
      final http = InterceptedHttp.build(interceptors: [
          WeatherApiInterceptor(),
      ]);
      final response =
          await http.get("$baseUrl/weather".toUri(), params: {'id': "$id"});
      if (response.statusCode == 200) {
        parsedWeather = json.decode(response.body);
      } else {
        return Future.error(
          "Error while fetching.",
          StackTrace.fromString("${response.body}"),
        );
      }
    } on SocketException {
      return Future.error('No Internet connection πŸ˜‘');
    } on FormatException {
      return Future.error('Bad response format πŸ‘Ž');
    } on Exception {
      return Future.error('Unexpected error 😒');
    }

    return parsedWeather;
  }

}

Retrying requests

Sometimes you need to retry a request due to different circumstances, an expired token is a really good example. Here's how you could potentially implement an expired token retry policy with http_interceptor.

class ExpiredTokenRetryPolicy extends RetryPolicy {
  @override
  Future<bool> shouldAttemptRetryOnResponse(ResponseData response) async {
    if (response.statusCode == 401) {
      // Perform your token refresh here.

      return true;
    }

    return false;
  }
}

You can also set the maximum amount of retry attempts with maxRetryAttempts property or override the shouldAttemptRetryOnException if you want to retry the request after it failed with an exception.

Using self signed certificates

You can achieve support for self-signed certificates by providing InterceptedHttp or InterceptedClient with the client parameter when using the build method on either of those, it should look something like this:

InterceptedClient

Client client = InterceptedClient.build(
  interceptors: [
    WeatherApiInterceptor(),
  ],
  client: IOClient(
    HttpClient()
      ..badCertificateCallback = badCertificateCallback
      ..findProxy = findProxy,
  );
);

InterceptedHttp

final http = InterceptedHttp.build(
  interceptors: [
    WeatherApiInterceptor(),
  ],
  client: IOClient(
    HttpClient()
      ..badCertificateCallback = badCertificateCallback
      ..findProxy = findProxy,
  );
);

Note: It is important to know that since both HttpClient and IOClient are part of dart:io package, this will not be a feature that you can perform on Flutter Web (due to BrowserClient and browser limitations).

Roadmap

Check out our roadmap here.

We migrated our roadmap to better suit the needs for development since we use ClickUp as our task management tool.

Troubleshooting

Open an issue and tell me, I will be happy to help you out as soon as I can.

Contributions

Contributions are always welcomed and encouraged, we will always give you credit for your work on this section. If you are interested in maintaining the project on a regular basis drop me a line at me@codingale.dev.

Contributors

Thanks to all the wonderful people contributing to improve this package. Check the Emoji Key for reference on what means what!


Alejandro Ulate Fallas

πŸ’» πŸ“– ⚠️ πŸ€” 🚧

Konstantin Serov

πŸ€”

Virus1908

πŸ€” πŸ’» ⚠️

Wes Ehrlichman

πŸ€” πŸ’» ⚠️

Jan LΓΌbeck

πŸ€” πŸ’» ⚠️

Lucas Alves

πŸ€” πŸ’» ⚠️

IstvΓ‘n Juhos

πŸ€” πŸ’» ⚠️

Scott Hyndman

πŸ€”

Islam Akhrarov

πŸ€” ⚠️ πŸ’»

Meysam

πŸ“–

Martijn

⚠️ πŸ’»

Libraries

extensions
http
http_interceptor
http_interceptor_exception
http_methods
intercepted_client
intercepted_http
interceptor_contract
models
query_parameters.util
request_data
response_data
retry_policy
string.extensions
uri.extensions
utils