http_services

A package to support the creation of Http services in a Dart application.

Features

• convenient methods to perform HTTP requests
• disposing a service will cleanup any pending requests, in order to avoid unwanted resources waste!
• convenient models to have a standard for request and response objects

RequestBase

Every request should extend RequestBase and implement its overrides:

• endpoint: Specify the path of the request
• toJson: This method is used for the request's serialization
• toData: This is an optional override in case you need to post a non JSON body. It returns an object of type T.

By default toData returns null

ResponseBase

Every response should extend ResponseBase

Exceptions

All the exceptions of this package extend HttpServiceException

ApiException:

This is thrown when something is wrong with the request (e.g. missing internet, resource not found, etc).

• networkError signals if there was an outage in connection
• httpCode is the received HTTP status code
• httpMessage is the received HTTP status message

UnexpectedStatusCodeException:

This is thrown when expected HTTP code doesn't match the received one.

• expected is the expected status code
• actual is the received status code

ResponseMappingException:

This is thrown when an error occurs while mapping the response.

RequestCanceledException:

This is thrown when a request is canceled.

HttpServiceBase

Every service should extend this.

To make a request within you service, you can use one of the following:

• getQuery: perform a GET request
• postData: perform a POST request
• postJson: perform a POST request with a JSON body
• putData: perform a PUT request
• putJson: perform a PUT request with a JSON body
• deleteData: perform a DELETE request
• deleteJson: perform a DELETE request with a JSON body
• patchData: perform a PATCH request
• patchJson: perform a PATCH request with a JSON body
• download: downloads a file
• getBytes: gets bytes from an endpoint

Example

import 'package:dio/dio.dart';
import 'package:http_services/http_services.dart';

import 'todos_service.dart';


class TodosRequest extends RequestBase {
  final int page;

  TodosRequest(this.page) : assert(page != null && page > 0);
  @override
  String get endpoint => '/todos/$page';

  @override
  Map<String, dynamic> toJson() {
    return {};
  }
}


class TodosResponse extends ResponseBase {
  final int userId;
  final int id;
  final String title;
  final bool completed;

  TodosResponse({
    this.userId,
    this.id,
    this.title,
    this.completed,
  });

  factory TodosResponse.fromJson(Map<String, dynamic> json) => TodosResponse(
        userId: json['userId'],
        id: json['id'],
        title: json['title'],
        completed: json['completed'],
      );
}


class TodosService extends HttpServiceBase {
  TodosService(Dio dioInstance) : super(dioInstance);

  Future<TodosResponse> getTodo(int page) {
    final request = TodosRequest(page);

    return getQuery(
      request: request,
      mapper: (json, _) => TodosResponse.fromJson(json),
    );
  }
}

void main() async {
  final dio = Dio(
    BaseOptions(
      baseUrl: 'https://jsonplaceholder.typicode.com/',
    ),
  );

  final service = TodosService(dio);

  try {
    print("Requesting data...");
    final response1 = await service.getTodo(1);
    print(
      "user id: ${response1.userId}\n"
      "id: ${response1.id}\n"
      "title: ${response1.title}\n"
      "completed: ${response1.completed}",
    );
  } on HttpServiceException catch (e) {
    print('Service exception: ${e.runtimeType}');
  }
}

Notes

There might be some cases where the JSON response is not like this:

{
  "data": [{"name": "Bob"},{"name":"Alice"}],
}

This will not be treated as a JSON since it's not a Map<String,dynamic> but it's a List<Map<String,dynamic>>. A solution might be to use the orElse parameter when performing the HTTP request. Remember that orElse is executed to map any response body that's not Map<String,dynamic>.

Similarly, if you ever find yourself in need of sending a JSON like the one above, a solution might be to override the onData method of RequestBase in your request object and then using the *data version of the request. For example:

class User{
  final String name;
  User(this.name);

  Map<String,dynamic> toJson() => {'name': name};
}

class UsersToSend extends RequestBase{
  final List<User> users;
  UsersToSend(this.users);

  @override
  Map<String,dynamic> toJson() => {};

  @override
  List<User> toData() => users;
}

and then use postData instead of using postJson in your service.

Contributors 🚀

• Debora Del Vecchio