Fix: example queued_interceptor_csrftoken.dart

example/lib/queued_interceptor_crsftoken.dart

@@ -1,92 +1,95 @@
-import 'dart:async';
-import 'dart:convert';
+import 'dart:developer';
 
 import 'package:dio/dio.dart';
 
+/// Used for Web Cookie
+// const String _cookieKey = 'XSRF_TOKEN';
+const String _headerKey = 'X-Csrf-Token';
+
 void main() async {
-  final dio = Dio();
-  //  dio instance to request token
-  final tokenDio = Dio();
-  String? csrfToken;
-  dio.options.baseUrl = 'https://seunghwanlytest.mocklab.io/';
-  tokenDio.options = dio.options;
+  String? cachedCSRFToken;
+
+  final dio = Dio()
+    ..options.baseUrl = 'https://httpbin.org/'
+    ..interceptors.add(
+      QueuedInterceptorsWrapper(
+        /// Add CSRF token to headers, if it exists
+        onRequest: (requestOptions, handler) {
+          if (cachedCSRFToken != null) {
+            requestOptions.headers[_headerKey] = cachedCSRFToken;
+          }
+          return handler.next(requestOptions);
+        },
+
+        /// Update CSRF token from [response] headers, if it exists
+        onResponse: (response, handler) {
+          final token = response.headers.value(_headerKey);
+          if (token != null) {
+            cachedCSRFToken = token;
+          }
+          return handler.resolve(response);
+        },
+      ),
+    );
+
+  /// Make Requests
+  await dio.get('/anything');
+  log('1) Called \'/anything\' CSRF Token: $cachedCSRFToken');
+
+  /// Expected 401 Exception
+  try {
+    await dio.post('/status/401');
+  } catch (e) {
+    log('2) Called \'/status/401\' CSRF Token: $cachedCSRFToken');
+  }
+
+  /// Add `onError` interceptor to request new CSRF token
   dio.interceptors.add(
     QueuedInterceptorsWrapper(
-      onRequest: (options, handler) async {
-        print('send request：path:${options.path}，baseURL:${options.baseUrl}');
+      /// Request new CSRF token
+      /// if the response status code is `401`
+      onError: (error, handler) async {
+        log('Error Detected: ${error.message}');
 
-        if (csrfToken == null) {
-          print('no token，request token firstly...');
+        if (error.response == null) return handler.next(error);
 
-          final result = await tokenDio.get('/token');
+        if (error.response?.statusCode == 401) {
+          try {
+            final tokenDio = Dio(
+              BaseOptions(baseUrl: error.requestOptions.baseUrl),
+            );
 
-          if (result.statusCode != null && result.statusCode! ~/ 100 == 2) {
-            /// assume `token` is in response body
-            final body = jsonDecode(result.data) as Map<String, dynamic>?;
+            /// Generate CSRF token
+            ///
+            /// This is a MOCK REQUEST to generate a CSRF token.
+            /// In a real-world scenario, this should be generated by the server.
+            final result = await tokenDio.post(
+              '/response-headers',
+              queryParameters: {
+                _headerKey: '94d6d1ca-fa06-468f-a25c-2f769d04c26c',
+              },
+            );
 
-            if (body != null && body.containsKey('data')) {
-              options.headers['csrfToken'] = csrfToken = body['data']['token'];
-              print('request token succeed, value: $csrfToken');
-              print(
-                'continue to perform request：path:${options.path}，baseURL:${options.path}',
-              );
-              return handler.next(options);
+            if (result.statusCode == null || result.statusCode! ~/ 100 != 2) {
+              throw DioException(requestOptions: result.requestOptions);
             }
-          }
 
-          return handler.reject(
-            DioException(requestOptions: result.requestOptions),
-            true,
-          );
-        }
+            final updatedToken = result.headers.value(_headerKey);
+            if (updatedToken == null) throw ArgumentError.notNull(_headerKey);
 
-        options.headers['csrfToken'] = csrfToken;
-        return handler.next(options);
-      },
-      onError: (error, handler) async {
-        /// Assume 401 stands for token expired
-        if (error.response?.statusCode == 401) {
-          print('the token has expired, need to receive new token');
-          final options = error.response!.requestOptions;
-
-          /// assume receiving the token has no errors
-          /// to check `null-safety` and error handling
-          /// please check inside the [onRequest] closure
-          final tokenResult = await tokenDio.get('/token');
-
-          /// update [csrfToken]
-          /// assume `token` is in response body
-          final body = jsonDecode(tokenResult.data) as Map<String, dynamic>?;
-          options.headers['csrfToken'] = csrfToken = body!['data']['token'];
-
-          if (options.headers['csrfToken'] != null) {
-            print('the token has been updated');
-
-            /// since the api has no state, force to pass the 401 error
-            /// by adding query parameter
-            final originResult = await dio.fetch(options..path += '&pass=true');
-            if (originResult.statusCode != null &&
-                originResult.statusCode! ~/ 100 == 2) {
-              return handler.resolve(originResult);
-            }
+            cachedCSRFToken = updatedToken;
+
+            return handler.resolve(error.response!);
+          } on DioException catch (e) {
+            return handler.reject(e);
           }
-          print('the token has not been updated');
-          return handler.reject(
-            DioException(requestOptions: options),
-          );
         }
-        return handler.next(error);
       },
     ),
   );
+  await dio.post('/status/401');
+  log('3) Called \'/status/401\' CSRF Token: $cachedCSRFToken');
 
-  FutureOr<void> onResult(d) {
-    print('request ok!');
-  }
-
-  /// assume `/test?tag=2` path occurs the authorization error (401)
-  /// and token to be updated
-  await dio.get('/test?tag=1').then(onResult);
-  await dio.get('/test?tag=2').then(onResult);
-  await dio.get('/test?tag=3').then(onResult);
+  await dio.get('/anything/posts');
+  log('4) Called \'/anything/posts\' CSRF Token: $cachedCSRFToken');
 }