I am trying to create a custom ApiClient class that I can inject as a dependency (with get_it package) to be used in the data layer of my application. In order not to worry about access tokens throughout the presentation/application/domain layers of my app, I'd like to have a field, accessToken, that keeps track of the accessToken inside the ApiClient (singleton) class.
The ApiClient class would be used all throughout my data layer to handle requests to my server for data. It should have a method that allows me to add my own requests to it for unique routes. Then, if those routes require access tokens, it will add the accessToken field from the class along with the request. If that access token is invalid (expired/tampered with), then I would use the refresh token from the device's storage and send a request to the server to get a new access token, then try the original request again. It would "retry" the request at maximum once. Then, if there's still an error, it just returns that to be handled.
I am really struggling with how to implement this. My current attempt is below. Any help would be amazing!
class ApiClient {
final String baseUrl;
final Dio dio;
final NetworkInfo networkInfo;
final FlutterSecureStorage secureStorage;
ApiClient(
{required this.baseUrl,
required this.dio,
required this.networkInfo,
required this.secureStorage}) {
dio.interceptors.add(RefreshInvalidTokenInterceptor(networkInfo, dio, secureStorage));
}
}
class RefreshInvalidTokenInterceptor extends QueuedInterceptor {
final NetworkInfo networkInfo;
final Dio dio;
final FlutterSecureStorage secureStorage;
String? accessToken;
RefreshInvalidTokenInterceptor(this.networkInfo, this.dio, this.secureStorage);
#override
Future onError(DioError err, ErrorInterceptorHandler handler) async {
if (_shouldRetry(err) && await networkInfo.isConnected) {
try {
// access token request (using refresh token from flutter_secure_storage)
final refreshToken = await secureStorage.read(key: "refreshToken");
final response = await dio.post(
"$kDomain/api/user/token",
queryParameters: {"token": refreshToken},
);
accessToken = response.data["accessToken"];
return err;
} on DioError catch (e) {
handler.next(e);
} catch (e) {
handler.next(err);
}
} else {
handler.next(err);
}
}
bool _shouldRetry(DioError err) =>
(err.response!.statusCode == 403 || err.response!.statusCode == 401);
}
There are similar questions online, but none seem to answer my question! :)
EDIT: I've gotten a working solution (almost), with just 1 error. This works (except in the function retryRequest() I'm hardcoding the request to be a post request):
<imports removed for simplicity>
class ApiClient {
final Dio dio;
final NetworkInfo networkInfo;
final FlutterSecureStorage secureStorage;
String? accessToken;
ApiClient({
required this.dio,
required this.networkInfo,
required this.secureStorage,
}) {
dio.options = BaseOptions(
connectTimeout: 5000,
receiveTimeout: 3000,
receiveDataWhenStatusError: true,
followRedirects: true,
headers: {"content-Type": "application/json"},
);
dio.interceptors.add(QueuedInterceptorsWrapper(
//! ON REQUEST
onRequest: (options, handler) {
handler.next(options);
},
//! ON RESPONSE
onResponse: (response, handler) {
print("onResponse...");
handler.next(response);
},
//! ON ERROR
onError: (error, handler) async {
print("onError...");
if (tokenInvalid(error)) {
print("token invalid: retrying");
print("header before: ${dio.options.headers}");
await getAccessTokenAndSetToHeader(dio);
print("header after: ${dio.options.headers}");
final response = await retryRequest(error, handler);
handler.resolve(response);
print("here-1");
} else {
handler.reject(error);
}
print("here-2");
print("here-3");
},
));
}
Future<String?> getRefreshToken() async => await secureStorage.read(key: "refreshToken");
Future<void> getAccessTokenAndSetToHeader(Dio dio) async {
final refreshToken = await secureStorage.read(key: "refreshToken");
if (refreshToken == null || refreshToken.isEmpty) {
print("NO REFRESH TOKEN ERROR; LOGOUT!!!");
throw ServerException();
} else {
final response = await dio.post(
"$kDomain/api/user/token",
data: {"token": refreshToken},
);
dio.options.headers["authorization"] = "Bearer ${response.data["accessToken"]}";
}
}
// This function has the hardcoded post
Future<Response> retryRequest(DioError error, ErrorInterceptorHandler handler) async {
print("retry called, headers: ${dio.options.headers}");
final retryResponse = await dio.post(error.requestOptions.path);
print("retry results: $retryResponse");
return retryResponse;
}
bool tokenInvalid(DioError error) =>
error.response?.statusCode == 403 || error.response?.statusCode == 401;
Future<void> refreshToken() async {}
bool validStatusCode(Response response) =>
response.statusCode == 200 || response.statusCode == 201;
}
However, if I change the hardcoded post request to:
final retryResponse =
await dio.request(error.requestOptions.path, data: error.requestOptions.data);
the code no longer works... anyone know why? Having it dynamic based on whatever the failed request was, lets me re-use this class.
package:dio already include the BaseOptions which you can use to add some basic configuration like the baseUrl.
After that, you could use interceptors to add the accessToken to every request. To do this depending on your state management solution you can update the accessToken when the user authentication state changes.
And finally regarding the token refresh you can checkout package:fresh_dio.
Figured it out! (code + how to use below)
Here is my entire ApiClient class (imports hidden for simplicity). It acts as an HTTP client using dio:
class ApiClient {
final Dio dio;
final NetworkInfo networkInfo;
final FlutterSecureStorage secureStorage;
String? accessToken;
/// The base options for all requests with this Dio client.
final BaseOptions baseOptions = BaseOptions(
connectTimeout: 5000,
receiveTimeout: 3000,
receiveDataWhenStatusError: true,
followRedirects: true,
headers: {"content-Type": "application/json"},
baseUrl: kDomain, // Domain constant (base path).
);
/// Is the current access token valid? Checks if it's null, empty, or expired.
bool get validToken {
if (accessToken == null || accessToken!.isEmpty || Jwt.isExpired(accessToken!)) return false;
return true;
}
ApiClient({
required this.dio,
required this.networkInfo,
required this.secureStorage,
}) {
dio.options = baseOptions;
dio.interceptors.add(QueuedInterceptorsWrapper(
// Runs before a request happens. If there's no valid access token, it'll
// get a new one before running the request.
onRequest: (options, handler) async {
if (!validToken) {
await getAndSetAccessTokenVariable(dio);
}
setHeader(options);
handler.next(options);
},
// Runs on an error. If this error is a token error (401 or 403), then the access token
// is refreshed and the request is re-run.
onError: (error, handler) async {
if (tokenInvalidResponse(error)) {
await refreshAndRedoRequest(error, handler);
} else {
// Other error occurs (non-token issue).
handler.reject(error);
}
},
));
}
/// Sets the current [accessToken] to request header.
void setHeader(RequestOptions options) =>
options.headers["authorization"] = "Bearer $accessToken";
/// Refreshes access token, sets it to header, and resolves cloned request of the original.
Future<void> refreshAndRedoRequest(DioError error, ErrorInterceptorHandler handler) async {
await getAndSetAccessTokenVariable(dio);
setHeader(error.requestOptions);
handler.resolve(await dio.post(error.requestOptions.path,
data: error.requestOptions.data, options: Options(method: error.requestOptions.method)));
}
/// Gets new access token using the device's refresh token and sets it to [accessToken] class field.
///
/// If the refresh token from the device's storage is null or empty, an [EmptyTokenException] is thrown.
/// This should be handled with care. This means the user has somehow been logged out!
Future<void> getAndSetAccessTokenVariable(Dio dio) async {
final refreshToken = await secureStorage.read(key: "refreshToken");
if (refreshToken == null || refreshToken.isEmpty) {
// User is no longer logged in!
throw EmptyTokenException();
} else {
// New DIO instance so it doesn't get blocked by QueuedInterceptorsWrapper.
// Refreshes token from endpoint.
try {
final response = await Dio(baseOptions).post(
"/api/user/token",
data: {"token": refreshToken},
);
// If refresh fails, throw a custom exception.
if (!validStatusCode(response)) {
throw ServerException();
}
accessToken = response.data["accessToken"];
} on DioError catch (e) {
// Based on the different dio errors, throw custom exception classes.
switch (e.type) {
case DioErrorType.sendTimeout:
throw ConnectionException();
case DioErrorType.connectTimeout:
throw ConnectionException();
case DioErrorType.receiveTimeout:
throw ConnectionException();
case DioErrorType.response:
throw ServerException();
default:
throw ServerException();
}
}
}
}
bool tokenInvalidResponse(DioError error) =>
error.response?.statusCode == 403 || error.response?.statusCode == 401;
bool validStatusCode(Response response) =>
response.statusCode == 200 || response.statusCode == 201;
}
It should be injected as a singleton to your project so there's one instance of it (for the sake of keeping the state of its accessToken field). I used get_it like so:
// Registers the custom ApiClient class.
sl.registerLazySingleton(() => ApiClient(dio: sl(), networkInfo: sl(), secureStorage: sl()));
Then, inside your data layer (or wherever you call APIs from), you can use it by passing it through the constructor:
class MyDatasource implements IMyDatasource {
final ApiClient apiClient;
late Dio api;
FeedDatasource({required this.client, required this.apiClient}) {
api = apiClient.dio;
}
// Logic for your class here.
}
I simplified it to api so I wouldn't have to go apiClient.dio... every call (optional).
Then, you can use it in one of your class' methods like so:
#override
Future<List<SomeData>> fetchSomeDataFromApi() async {
try {
final response = await api.post("/api/data/whatYouWant");
throw ServerException();
} catch (e) {
throw ServerException();
}
}
Now, for this request, if your class has a valid access token (non-null, non-empty, non-expired), it will call normally. However, if your token isn't valid, it'll refresh it first, then proceed with your call. Even if the call fails after the token originally passed the validation check (token somehow expires during the call for example), it will still be refreshed, and the call re-executed.
Note: I use a lot of custom exceptions, this is optional.
Hopefully this helps someone else!
Related
Hi im using http interceptor in dart to handle refreshtoken,
How can i call the api request again once the refreshtoken api is called in using thee interceptor and got the new accesstoken.
class ExpiredTokenRetryPolicy extends RetryPolicy {
#override
Future<bool> shouldAttemptRetryOnResponse(ResponseData response) async {
if (response.statusCode == 401) {
await GetFitbitAccessToken().getAccessToken();
return true;
}
return false;
}
}
------------------------------------
Client client = InterceptedClient.build(
interceptors: [
FitbitApiInterceptor(),
],
retryPolicy: ExpiredTokenRetryPolicy(),
);
Basically you need error 401(UnAuthorized) does not necessarily mean the token has expired so I believe you should have a refresh token to handle such cases. If your API has a refresh token then do this.
class ExpiredTokenRetryPolicy extends RetryPolicy {
#override
Future<bool> shouldAttemptRetryOnResponse(ResponseData response) async {
if (response.statusCode == 200) {
// do your normal request
return true;
}else if(response.statusCode =401){
//for POST
///within the header add this
headers: {'grant_type': 'refresh_token', 'refresh_token':
'$refresh_token'});
token = jsonDecode(response.body)['token'];
refresh_token = jsonDecode(response.body)['refresh_token'];
return true;
}
return false;
}
}
After login i setting user token to my user Secure storage. Like :
Future<AuthResponseModel?> login(AuthRequstModel model) async {
try {
Response response = await _dio.post(loginPath, data: model);
if (response.statusCode == 200) {
final AuthResponseModel authResponseModel = AuthResponseModel.fromJson(response.data);
if (authResponseModel.success!) {
await UserSecureStorage.setField("token", authResponseModel.token);
}
return AuthResponseModel.fromJson(response.data);
}
return null;
} catch (e) {
return null;
}
}
User Secure Storage =>
class UserSecureStorage {
static const _storage = FlutterSecureStorage();
static Future setField(String key, value) async {
await _storage.write(key: key, value: value);
}
static Future<String?> getField(key) async {
return await _storage.read(key: key);
}
But problem is when i want to make apiservice and when i want to auth token inside header of dio, I cant access it becouse its a future<String?> function. But i cant use await coz its inside of baseoption. Like :
class ApiService {
final _dio = Dio(BaseOptions(headers: {
'authorization': 'Bearer ${UserSecureStorage.getField("token")}', //I cant access here its only giving instance.
}));
Future<Response?> get(String path) async {
try {
Response response = await _dio.get('${ApiConstants.BASE_URL}$path');
if (response.statusCode == 200) {
return response;
}
return null;
} on DioError catch (e) {
return null;
}
}
What can i do for solve that problem ? I tried use .then(value=>value) after tried get token but didnt work too. Thanks for responses!
I think token is not getting updated because _dio is already intitalized.
Try to request for token when dio request is made like :
class ApiService {
final _dio = Dio();
Future<Response?> get(String path) async {
try {
Response response = await _dio.get('${ApiConstants.BASE_URL}$path', options: Options(headers: {"authorization": "Bearer ${UserSecureStorage.getField("token")}"}));
if (response.statusCode == 200) {
return response;
}
return null;
} on DioError catch (e) {
return null;
}
}
Use options in get method to add headers for a single request or interceptors for all requests.
I think that it is not an issue easily solvable, I would try with two different methods, you can maintain the token in a state manager such as Provider so you don't have to rely on an async function to retrive it, but this of course add in the code the state manager structure that complicates thing a little.
A bit more naive way to solve this could be to include a async initializator in the ApiService class such this
class ApiService {
late final _dio;
Future<void> init() async {
_dio = Dio(BaseOptions(headers: {
'authorization': 'Bearer ${UserSecureStorage.getField("token")}', //I cant access here its only giving instance.
}));}
Future<Response?> get(String path) async {
try {
Response response = await _dio.get('${ApiConstants.BASE_URL}$path');
if (response.statusCode == 200) {
return response;
}
return null;
} on DioError catch (e) {
return null;
}
}
And this introduce us a new issue, we have to call init everytime the class ApiService is instantiated, to solve this you could use the package get_it which grants you the possibility to instatiate only once the class and access it from everywhere in your project.
I hope this will help you solve your problem
your are getting instance because UserSecureStorage.getField("token") is future so you can get token when you put await keyword
so try like this
await UserSecureStorage.getField("token")
I have declared a class to make api requests using flutter Dio as follows.
class DioUtil {
static Dio _instance;
static Dio getInstance() {
if (_instance == null) {
_instance = createDio();
}
return _instance;
}
static Dio createDio() {
var dio = Dio();
dio.interceptors.add(InterceptorsWrapper(onRequest: (options, handler) {
// Do something before request is sent
return handler.next(options); //continue
}, onResponse: (response, handler) {
// Do something with response data
return handler.next(response); // continue
}, onError: (DioError e, handler) async {
if (e.response != null) {
if (e.response.statusCode == 401) {
var dio = DioUtil.getInstance();
dio.interceptors.requestLock.lock();
dio.interceptors.responseLock.lock();
RequestOptions requestOptions = e.requestOptions;
await refreshToken();
Repository repository = Repository();
var accessToken = await repository.readData("accessToken");
final opts = new Options(
method: requestOptions.method
);
dio.options.headers["Authorization"] = "Bearer " + accessToken;
dio.interceptors.requestLock.unlock();
dio.interceptors.responseLock.unlock();
dio.request(requestOptions.path,
options: opts,
data: requestOptions.data,
queryParameters: requestOptions.queryParameters);
}//TODO: handle else clause
}
}));
return dio;
}
static refreshToken() async {
Response response;
Repository repository = Repository();
var dio = Dio();
final Uri apiUrl = Uri.parse(BASE_PATH + "auth/reIssueAccessToken");
var refreshToken = await repository.readData("refreshToken");
dio.options.headers["Authorization"] = "Bearer " + refreshToken;
response = await dio.postUri(apiUrl);
if (response.statusCode == 200) {
LoginResponse loginResponse =
LoginResponse.fromJson(jsonDecode(response.toString()));
repository.addValue('accessToken', loginResponse.data.accessToken);
repository.addValue('refreshToken', loginResponse.data.refreshToken);
} else {
print(response.toString());
}
}
}
and I use flutter bloc pattern and my bloc is as follows.
class OurClassBloc extends Bloc<OurClassEvent, OurClassState> {
OurClassBloc(OurClassState initialState) : super(initialState);
Repository repository = Repository();
#override
Stream<OurClassState> mapEventToState(
OurClassEvent event,
) async* {
if (event is GetClasses) {
yield* _getClassCategories(event);
}
}
Stream<OurClassState> _getClassCategories(GetClasses event) async* {
Response response;
var dio = DioUtil.getInstance();
final String apiUrl = (BASE_PATH + "classCategories");
var accessToken = await repository.readData("accessToken");
Map<String, dynamic> map = {"active": event.active};
dio.options.headers["Authorization"] = "Bearer " + accessToken;
dio.options.headers["Accept"] = "*/*";
try {
response = await dio.get(apiUrl, queryParameters: map);
if (response.statusCode == 200) {
OurClassResponse loginResponse =
OurClassResponse.fromJson(jsonDecode(response.toString()));
yield OurClassSuccess(loginResponse);
}
if (response.statusCode >= 400) {
yield OurClassFailed();
}
} catch (e) {
yield OurClassFailed();
}
}
}
When I make the requests with valid access token, I get 200 status code in bloc class and api works fine.when the token is expired, the dio class correctly gets the new token, make the same api call with new token successfully and inside the below callback I get the correct response also.
onResponse: (response, handler) {
return handler.next(response);
}
but response doesn't comes to bloc class. Though it returned the response by calling return handler.next(response);,it is not coming to response variable inside _getClassCategories method.I expect the correct response should come to the response variable in bloc class for both scenarios:
makes the api call with valid token.
makes the api call with expired token.
but only scenario 1 is working in my code and hope someone here can help me to fix this.
EDIT- this works fine with dio previous version(3.0.10) - code
dio.request(requestOptions.path,
options: opts,
data: requestOptions.data,
queryParameters: requestOptions.queryParameters);
This line creates a new request with no relation to the original one. If the request succeeds, there is no code listening for a response. If you want the original caller to receive anything, you will need to forward the response to the original handler:
try {
final response = await dio.request(requestOptions.path,
options: opts,
data: requestOptions.data,
queryParameters: requestOptions.queryParameters);
handler.resolve(response);
} on DioError catch (error) {
handler.next(error); // or handler.reject(error);
}
Also, be sure to forward the error to the handler in non-401 cases as well. Dio 4.0.0 interceptors don't automatically forward anything.
Now I am using dio(4.0.0) as my http client in flutter 2.x, I want to refresh the token, but now I encount a problem: when the auth token is invalid, I just want only one request send to server to refresh token. But now the http request is async and when the token invalid, many request send to server to refresh token, althrough finnaly the token could successfully refreshed, but you know the server must handle some invalid repeat token refresh request.What should I to to optimize the client only one request send to server to refresh token? this is the code I am using now:
class AppInterceptors extends InterceptorsWrapper {
#override
Future<void> onRequest(RequestOptions options, RequestInterceptorHandler handler) async {
if (!options.headers.containsKey("token")) {
String? token = await storage.read(key: "token");
options.headers["token"] = token;
}
handler.next(options);
}
#override
Future onResponse(Response response, ResponseInterceptorHandler handler) async {
autoLogin(response);
return super.onResponse(response, handler);
}
#override
Future onError(DioError err, ErrorInterceptorHandler handler) async {
return super.onError(err, handler);
}
void autoLogin(Response response) async {
String loginInvalidCode = ResponseStatus.LOGIN_INVALID.statusCode;
String notLoginCode = ResponseStatus.NOT_LOGIN.statusCode;
String statusCode = response.data["statusCode"];
if (statusCode == loginInvalidCode || statusCode == notLoginCode) {
Dio dio = RestClient.createDio();
String? userName = await storage.read(key: "username");
String? password = await storage.read(key: "password");
if (userName != null && password != null) {
refreshAuthToken(dio, userName, password, response);
} else {
NavigationService.instance.navigateToReplacement("login");
}
}
}
void refreshAuthToken(Dio dio, String userName, String password, Response response) async {
dio.lock();
try {
AuthResult result = await Auth.login(username: userName, password: password, loginType: LoginType.PHONE);
if (result.result == Result.ok) {
// resend a request to fetch data
Dio req = RestClient.createDio();
req.request(response.requestOptions.path);
}
} on Exception catch (e) {
CruiseLogHandler.logErrorException("login failed", e);
} finally {
dio.unlock();
}
}
}
the better way to only send one request to server to refresh token. But I do not know how to do it. I want the refresh logic better smooth.
I'm only posting this as an answer because its cumbersome to write all this in the comments.
I was about to recommend to you locking the interceptors , but you already do so.
Even though that you have repeated requests?
The other thing I see is that you are unconditionally calling the autologin in onResponse
That I think could be more granular as:
#override
Future onResponse(Response response, ResponseInterceptorHandler handler) async {
if(response?.statusCode == 401){
// I think you should move the locking up here so you stop other requests earlier.
// dio.interceptors.requestLock.lock();
await autoLogin(response); // You had a missing await here
// dio.interceptors.requestLock.unlock()
}
return super.onResponse(response, handler);
}
I also noted that you pass a new client as Dio dio = RestClient.createDio(); is that a singleton?, because if not you might be locking another client
Here is my interceptor setup :
class AppInterceptor extends Interceptor {
Dio dio = Dio();
Dio previous;
AppInterceptor() {}
AppInterceptor.firebaseIDToken() {
this.dio.interceptors.add(
InterceptorsWrapper(onRequest: (options, handler) async {
var token = await getAuthorizationToken();
options.headers["Authorization"] = 'Bearer $token';
dio.unlock();
handler.next(options);
}, onResponse: (response, handler) {
return handler.next(response);
}, onError: (DioError e, handler) {
return handler.next(e);
}
),
);
}
...
}
And here is how I make http request:
Response response;
if (user != null) {
response = await AppInterceptor.tokenAuthorization()
.dio.get(Global.apiurl + 'jobs/detail/$pageid?
coordinates=$coordinates');
} else {
response = await AppInterceptor.apikey().dio.get(Global.apiurl +
'jobs/detail/$pageid?coordinates=$coordinates');
}
return Job.fromJson(response.data);
Now what I want to do is add the dio HTTP cache interceptor
https://pub.dev/packages/dio_http_cache
dio.interceptors.add(DioCacheManager(CacheConfig(baseUrl: "http://www.google.com")).interceptor);
google.com here should be my Global.apiurl
My question is, how do I go about adding this to my above implementation?
I stumbled upon this problem earlier and actually found my way through Dio's doc. I learned that handler actually have method other than next which is resolve.
To resolve onError with custom Response (in this case, something from your cache), you should resolve the handler instead of passing it through next.
I made the interceptor as it's own class and specifically return cached response only on Connection Timeout & Other Error.
class CacheInterceptor extends Interceptor {
final _cache = <Uri, Response>{};
#override
onRequest(options, handler) => handler.next(options);
#override
onResponse(response, handler) {
// Cache the response with uri as key
_cache[response.requestOptions.uri] = response;
handler.resolve(response);
}
#override
onError(DioError err, handler) {
var isTimeout = err.type == DioErrorType.connectTimeout;
var isOtherError = err.type == DioErrorType.other;
if (isTimeout || isOtherError) {
// Read cached response if available by uri as key
var cachedResponse = _cache[err.requestOptions.uri];
if (cachedResponse != null) {
// Resolve with cached response
return handler.resolve(cachedResponse);
}
}
return handler.next(err);
}
}
And then, add the CacheInterceptor above to the Dio instance
...
dio.interceptors
..add(CacheInterceptor())
..add(LogInterceptor());
...