Not Firing Interceptors in Flutter - flutter

Question

Flutter Custom Interceptors code here, it is showing error on onRequest Method as well as onResponse Method and onError Method. recently started flutter implementation.
class AppInterceptors extends Interceptor {
Dio _dio = Dio();
SharedPreferences _prefs;
TokenAnalyzer _tokenAnalyzer;
AppInterceptors(this._dio, this._tokenAnalyzer);
#override
Future<dynamic> onRequest(RequestOptions options) async {
_prefs = await _sharedPreferences;
var accessToken = _prefs.get("access_token") ?? '';
return options;
}
#override
Future<dynamic> onResponse(Response options) async {
return options;
}
#override
Future<dynamic> onError(DioError dioError) async {
if (dioError.type == DioErrorType.response &&
dioError.response.statusCode < 200 ||
dioError.response.statusCode > 400) {
if (dioError.response.statusCode == 500) {
prefs.setString("ErrorMessage", dioError.response.data);
errorService.showErrorMessage(dioError.response.data);
throw (dioError.response.data);
} else if (dioError.response.statusCode == 401) {
var _prefs = await _sharedPreferences;
prefs.setString("ErrorMessage", dioError.response.data);
}
}
return null;
}
Here it is another file implemented DIO instillation
class DioHttpClient {
Dio _dio = Dio();
BaseOptions options = new BaseOptions(
receiveTimeout: 1000 * 60,
headers: {'Content-Type': 'application/json', 'Authorization': ''});
DioHttpClient(TokenAnalyzer tokenAnalyzer) {
_dio = new Dio(options);
_dio.interceptors.add(AppInterceptors(_dio, tokenAnalyzer));
}
Dio get HttpClient {
return _dio;
}
}
API Call Code below:
Dio _httpClient1 = Dio();
Future<T> post<T>(url, body, {allowAnnoymous = false}) async {
SharedPreferences prefs = await SharedPreferences.getInstance();
try {
print("called new post method $url");
clientService.isBusy = true;
String token = prefs.get("AccessToken");
Response response = await _httpClient1.post<T>(url,
data: jsonEncode(body),
options: Options(headers: {
"allowanonymous": allowAnnoymous.toString(),
'Authorization': 'Bearer $token',
}));
print("==================== success post");
throwError(response);
return response.data;
} catch (ex) {
throwErrorMessage();
throw ex;
}
}
I am getting below error and it is showing error Like this
'AppInterceptors.onRequest' ('Future<dynamic> Function(RequestOptions)') isn't a valid override of 'Interceptor.onRequest' ('void Function(RequestOptions, RequestInterceptorHandler)').
Could you please help me anyone !! thanks Advance !!!

Answer 1

Error says it all:
'AppInterceptors.onRequest' ('Future<dynamic> Function(RequestOptions)') isn't a valid override of 'Interceptor.onRequest' ('void Function(RequestOptions, RequestInterceptorHandler)').
You have
Future<dynamic> Function(RequestOptions)
Shoud be
void Function(RequestOptions, RequestInterceptorHandler)
See example.

Answer 2

You have missed RequestInterceptorHandler in arguments of onRequest method.
override
Future<dynamic> onRequest(RequestOptions options, RequestInterceptorHandler handler) async {
_prefs = await _sharedPreferences;
var accessToken = _prefs.get("access_token") ?? '';
return
options;
}

Answer 3

You will have to change all the three overridden method's declaration ( onError, onResponse, and onRequest), with like something below:
import 'package:dio/dio.dart';
class Intercept extends Interceptor {
#override // add errorInterceptorHandler param
Future<dynamic> onError(DioError error, errorInterceptorHandler) async {
// replace with your logic
if (error.type == DioErrorType.connectTimeout ||
error.type == DioErrorType.response) {
print(error.response);
print("CONNECTION TIMEOUT");
}
return error;
}
#override // add responseInterceptorHandler param
Future<dynamic> onResponse(Response response, responseInterceptorHandler) async {
// replace with your logic
if (response.statusCode == 200) {
print("RESPONSE--------->");
print(response.data);
print("<--------------------");
}
return response;
}
#override // add requestInterceptorHandler param
Future<dynamic> onRequest(RequestOptions request, requestInterceptorHandler) async {
// replace with your logic
print("REQUESTING--------->");
print(request.headers);
print("<--------------------");
return request;
}
}