const baseUrl = "your url";

class ApiClient {
  Dio _dio;

  ApiClient() {
    BaseOptions options = new BaseOptions(
      baseUrl: baseUrl,
      connectTimeout: 20000,
      receiveTimeout: 30000,
      responseType: ResponseType.json,
      headers: {'accept': 'application/json'},
    );
    _dio = new Dio(options);

    _dio.interceptors
        .add(InterceptorsWrapper(onRequest: (RequestOptions options) async {
      logger.i('${options.method}: ${options.uri}');
      return options;
    }, onResponse: (Response response) async {
      logger.i(
          '(${response.statusCode}) ${response.request.method}: ${response.request.uri} \n ${response.data}');
      return response; // continue
    }, onError: (DioError e) async {
      if (e.response != null) {
        logger.e(
            '(${e.response.statusCode}) ${e.response.request.method}: ${e.response.request.uri} \n ${e.response.data}');
      } else {
        logger.e(e);
      }
      return e; //continue
    }));
  }

  Future<User> createUser(username, password) async {
    try {
      Response response = await _dio.request(
        "/user",
        data: {
            'username': username,
            'password': password
        },
        options: Options(
          method: "POST",
        ),
      );
      return Transaction.fromMap(response.data);
    } catch (error) {
      throw error;
    }
  }
}

//Usage

createUserExampleMethod() {
    ApiClient apiClient= new ApiClient();
    apiClient.createUser(username: '', password: '')
          .then((User user) {
            //You got yourself a user model here
          }
}

//User Model Example

class User {
  String id;
  String username;


  User(
    this.id,
    this.username,
  );

  User.name(
    this.id,
    this.username,
  );

  User.fromMap(Map<String, dynamic> user) {
    this.id = user['id'];
    this.username= user['username'];
  }
}