Flutter: How to refresh token when token expires with ferry (graphql) client?

Question

How to retrieve a new token with a refresh token in flutter in a ferry (graphql) client?

The response after a mutation looks like this:

{
  "data": {
    "auth_login": {
      "access_token": "ey...",
      "refresh_token": "Ua...",
      "expires": 900000
    }
  }
}

I tried to accomplish it with fresh_graphql, but it does not work. The authenticationStatus is always unauthenticated but the token was always legit.

Implementation:

import 'dart:math';

import 'package:ferry/ferry.dart';
import 'package:ferry_hive_store/ferry_hive_store.dart';
import 'package:fresh_graphql/fresh_graphql.dart';
import 'package:gql_http_link/gql_http_link.dart';
import 'package:hive/hive.dart';

Future<Client> initClient(String? accessToken, String? refreshToken) async {
  Hive.init('hive_data');

  final box = await Hive.openBox<Map<String, dynamic>>('graphql');

  await box.clear();

  final store = HiveStore(box);

  final cache = Cache(store: store);

  final freshLink = await setFreshLink(accessToken ?? '', refreshToken);

  final link = Link.from(
      [freshLink, HttpLink('https://.../graphql/')]);

  final client = Client(
    link: link,
    cache: cache,
  );

  return client;
}

Future<FreshLink> setFreshLink(String accessToken, String? refreshToken) async {
  final freshLink = FreshLink<dynamic>(
    tokenStorage: InMemoryTokenStorage<dynamic>(),
    refreshToken: (dynamic token, client) async {
      print('refreshing token!');
      await Future<void>.delayed(const Duration(seconds: 1));
      if (Random().nextInt(1) == 0) {
        throw RevokeTokenException();
      }
      return OAuth2Token(
        accessToken: 'top_secret_refreshed',
      );
    },
    shouldRefresh: (_) => Random().nextInt(2) == 0,
  )..authenticationStatus.listen(print);

  print(freshLink.token);
  print(freshLink.authenticationStatus);

  await freshLink
      .setToken(OAuth2Token(tokenType: 'Bearer', accessToken: accessToken));

  return freshLink;
}

Any solution, even without fresh_graphql, would be appreciated!

Answer 1

The way I initialize my ferry client is as follows.

1. Create a CustomAuthLink that inherits from AuthLink.

   import 'package:gql_http_link/gql_http_link.dart';
   
   class _CustomAuthLink extends AuthLink {
      _CustomAuthLink() : super(
         getToken: () {
           // ...
           // Call your api to refresh the token and return it
           // ...
           String token = await ... // api refresh call
           return "Bearer $token"
         }
      );
   }
   

2. Use this custom auth link to initialise your client.

   ...
   final link = Link.from([freshLink, HttpLink('https://.../graphql/')]); 
   ...
   Client(
     link: _CustomAuthLink().concat(link),
   )
   ...
   

3. I am not sure if you still going to need freshLink anymore. You might wanna remove it and pass HttpLink(...) directly into the .concat(...) method.