A simple wrapper for dio with response typing and full backward compatibility.
Inspired by chopper.

This package currently in beta. Use it with caution.

Features

• Safe typing of successful and unsuccessful responses.
• Expected behavior.
• Does not affect basic Dio functionality including other plugins or interceptors.
• Simple and familiar Dio like api.
• Core concept is receiving a response as either type to utilize the exhaustive pattern.
• No external dependencies.

Basic usage:

// ignore_for_file: avoid_print
import 'package:dio/dio.dart';
import 'package:tio/tio.dart';

class User {
  User.fromJson(Map<String, dynamic> json) : id = json['id'] as int;

  final int id;
}

class MyError {
  const MyError.fromString(this.errorMessage);

  const MyError.empty() : errorMessage = 'Unknown message';

  MyError.fromJson(Map<String, dynamic> json)
      : errorMessage = json['message'] as String;

  final String errorMessage;
}

const factoryConfig = TioFactoryConfig<MyError>(
  [
    TioJsonFactory<User>(User.fromJson),
  ],
  // Factory for error transformation
  errorGroup: TioFactoryGroup(
    // when response body is empty (or empty string)
    empty: TioEmptyFactory(MyError.empty),
    string: TioStringFactory(MyError.fromString), // string
    json: TioJsonFactory(MyError.fromJson), // or json
  ),
);

final dio = Dio();
final tio = Tio<MyError>(
  dio: dio, // Tio uses dio under the hood
  factoryConfig: factoryConfig,
);

Future<TioResponse<User, MyError>> getUser(int id) =>
    tio.get<User>('/users/$id').one();

Future<TioResponse<List<User>, MyError>> getUsers() =>
    tio.get<User>('/users').many();

Future<TioResponse<User, MyError>> updateUser(int id, String name) =>
    tio.post<User>('/users/$id', data: {'name': name}).one();

Future<TioResponse<String, MyError>> geString() =>
    tio.get<String>('/text').string();

void main() async {
  switch (await getUser(1)) {
    case TioSuccess<User, MyError>(result: final user):
      print('user id is ${user.id}');
    case TioFailure<User, MyError>(error: final error):
      print('error acquired ${error.errorMessage}');
  }
}

Guide

Common

Tio mirrors the common methods of Dio such as get, post, put etc. but returns proxy object as a result that might be transformed by additional methods like one(), many(), string() etc.

Future<TioResponse<User, MyError>> getUser(int id) =>
    tio.get<User>('/users/$id').one();

Future<TioResponse<List<User>, MyError>> getUsers() =>
    tio.get<User>('/users').many();

Future<TioResponse<User, MyError>> updateUser(int id, String name) =>
    tio.post<User>('/users/$id', data: {'name': name}).one();

Future<TioResponse<String, MyError>> getString() =>
    tio.get<String>('/text').string();

Using TioApi helper class [Optional]

class UserApi extends TioApi<MyError> {
    UserApi({required super.tio}) : super(path: '/users');

    Future<TioResponse<User, MyError>> getUser(int id) =>
        get<User>('/$id').one();

    Future<TioResponse<List<User>, MyError>> getUsers() =>
        get<User>('/').many();
}

How Tio knows that response is unsuccessful?

With the Options.validateStatus property.
Tio transforms any DioException with type badResposce into an ErrorT then returns TioFailure<..., ErrorT> instead of throwing an exception.

Tips & Tricks

Alias usage to slightly reduce code size.

typedef MyResponse<T> = TioResponse<T, MyError>;

Future<MyResponse<User>> getUser(int id) =>
    tio.get<User>('/users/$id').one();

Check tests for additional usage info.

Initially this library was created for personal usage.