how to resend multipart request - flutter

Question

I am retrying my api call if get 401 response but when Retrying I am ending with an following exception
following is my code for retrying multipart I had used http_interceptor package for retrying Api Calls
interceptor.dart
class AuthorizationInterceptor extends InterceptorContract {
#override
Future<BaseRequest> interceptRequest({required BaseRequest request}) async {
final prefs = await SharedPreferences.getInstance();
final extractData =
json.decode(prefs.getString('userData')!) as Map<String, dynamic>;
final Map<String, String> headers = Map.from(request.headers);
headers['Authorization'] = await extractData['accessToken'];
print(
'this is from AuthorizationInterceptor: ${extractData['accessToken']}');
// TODO: implement interceptRequest
return request.copyWith(
headers: headers,
);
}
retry.dart
class ExpiredTokenRetryPolicy extends RetryPolicy {
BuildContext context;
ExpiredTokenRetryPolicy(this.context);
#override
// TODO: implement maxRetryAttempts
int get maxRetryAttempts => 2;
#override
Future<bool> shouldAttemptRetryOnResponse(BaseResponse response) async {
if (response.statusCode == 401) {
print('retry token started');
//perform token refresh,get the new token and update it in the secure storage
await Provider.of<Auth>(context, listen: false).restoreAccessToken();
return true;
}
return false;
}
I am using interceptors in my widget following is my code where I am using interceptors and using retry policy
#override
Widget build(BuildContext context) {
var flutterFunctions = Provider.of<FlutterFunctions>(context);
// print('this is from insert package${token.token}');
ApiCalls repository = ApiCalls(
client: InterceptedClient.build(
retryPolicy: ExpiredTokenRetryPolicy(context),
interceptors: [
AuthorizationInterceptor(),
],
),
);
following is my restore access token method
Future<void> restoreAccessToken() async {
print('restoreAccessToken started');
//print(token);
final url = '${Ninecabsapi().urlHost}${Ninecabsapi().login}/$sessionId';
var response = await http.patch(
Uri.parse(url),
headers: {
'Content-Type': 'application/json; charset=UTF-8',
'Authorization': accessToken!
},
body: json.encode(
{"refresh_token": refreshtoken},
),
);
var userDetails = json.decode(response.body);
if (response.statusCode == 401) {
print(userDetails['messages']);
}
sessionId = userDetails['data']['session_id'];
accessToken = userDetails['data']['access_token'];
accessTokenExpiryDate = DateTime.now().add(
Duration(seconds: userDetails['data']['access_token_expiry']),
);
refreshToken = userDetails['data']['refresh_token'];
refreshTokenExpiryDate = DateTime.now().add(
Duration(seconds: userDetails['data']['refresh_token_expiry']),
);
final userData = json.encode({
'sessionId': sessionId,
'refreshToken': refreshToken,
'refreshExpiry': refreshTokenExpiryDate!.toIso8601String(),
'accessToken': accessToken,
'accessTokenExpiry': accessTokenExpiryDate!.toIso8601String()
});
//print(userDetails);
notifyListeners();
final prefs = await SharedPreferences.getInstance();
prefs.setString('userData', userData);
print("this is from restoreAcessToken :$userDetails");
final extractData =
json.decode(prefs.getString('userData')!) as Map<String, dynamic>;
print('restore access token: ${extractData['accessToken']}');
reset();
}

Answer 1

As a rule. You must NOT write using the same Stream/MultipartFile more than once. If you need to retry sending to the same destination, you have to use a new MultipartFile each time you retry.