如何在 DIO 包中添加响应头

Question

我一直遇到 CORS XMLHttpRequest 错误

CORS 政策已阻止从源“http://localhost:49234”访问“https://maps.googleapis.com/maps/api/place/autocomplete/json?params”处的 XMLHttpRequest：响应预检请求未通过访问控制检查：请求的资源上不存在“Access-Control-Allow-Origin”标头。

这是我的代码

///get information of a place after getting its place ID from places autocomplete


Future<Place?> getPlaceDetails(String placeID, String sessionToken,
      [Locale? locale]) async {
    try {
      var dio = Dio();
      dio.options.headers = AppValues.headers;
      dio.options.responseType = ResponseType.plain;
      var response = await dio.get(detailsUrl(placeID, sessionToken, locale));
      var json = convert.jsonDecode(response.data.toString());
      var jsonResult = json[_f.result] as Map<String, dynamic>;
      return Place.fromMap(jsonResult);
    } catch (e) {
      return null;
    }

}

我读到了这个问题的答案，说必须在响应标头中添加“Access-Control-Allow-Origin”，而不是在请求标头中，这就是我相信我正在做的事情。我已经有这个错误好几天了，需要一个永久的解决方案。我已经阅读了有关临时解决方案的答案，例如安装插件或禁用网络安全。但是需要一个在我部署时可以工作的解决方案。无论是添加响应标头（以及如何添加），还是任何其他标头。请提供帮助，并衷心感谢您抽出宝贵时间提供任何帮助。

这是控制台中的错误日志

errors.dart:202 Uncaught (in promise) Error: DioError [DioErrorType.response]: XMLHttpRequest error.
Source stack:
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/core_patch.dart 926:28                get current
packages/dio/src/dio_mixin.dart 473:35                                                                                         fetch
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                runBody
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5                _async
packages/dio/src/dio_mixin.dart 472:31                                                                                         fetch
packages/dio/src/dio_mixin.dart 468:12                                                                                         request
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                runBody
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5                _async
packages/dio/src/dio_mixin.dart 438:33                                                                                         request
packages/dio/src/dio_mixin.dart 55:12                                                                                          get
packages/app/services/places_service.dart 35:29                                                                                getAutoComplete
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                runBody
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5                _async
packages/app/services/places_service.dart 27:45                                                                                getAutoComplete
packages/app/blocs/map_bloc.dart 39:57                                                                                         searchPlaces
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                runBody
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5                _async
packages/app/blocs/map_bloc.dart 38:31                                                                                         searchPlaces
packages/app/custom/search_map.dart 132:36                                                                                     onChanged
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                runBody
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5                _async
packages/app/custom/search_map.dart 130:14                                                                                     onChanged
packages/flutter/src/material/text_form_field.dart 198:25                                                                      onChangedHandler
packages/flutter/src/widgets/editable_text.dart 2552:27                                                                        [_formatAndSetValue]
packages/flutter/src/widgets/editable_text.dart 1917:7                                                                         updateEditingValue
packages/flutter/src/services/text_input.dart 1596:9                                                                           _handleTextInputInvocation
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                runBody
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5                _async
packages/flutter/src/services/text_input.dart 1538:45                                                                          [_handleTextInputInvocation]
packages/flutter/src/services/platform_channel.dart 414:55                                                                     _handleAsMethodCall
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                runBody
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5                _async
packages/flutter/src/services/platform_channel.dart 411:40                                                                     [_handleAsMethodCall]
packages/flutter/src/services/platform_channel.dart 407:34                                                                     <fn>
packages/flutter/src/services/binding.dart 377:35                                                                              <fn>
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                runBody
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5                _async
packages/flutter/src/services/binding.dart 374:98                                                                              <fn>
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine/platform_dispatcher.dart 1042:13               invoke2
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/ui/channel_buffers.dart 25:12                                 invoke
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/ui/channel_buffers.dart 65:7                                  push
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/ui/channel_buffers.dart 130:16                                push
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine/platform_dispatcher.dart 304:25                invokeOnPlatformMessage
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine/text_editing/text_editing.dart 1711:39         updateEditingState
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine/text_editing/text_editing.dart 1817:17         <fn>
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine/text_editing/text_editing.dart 1017:7          handleChange
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 334:14  _checkAndCall
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 339:39  dcall
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/html/dart2js/html_dart2js.dart 37277:58                              <fn>

    at Object.throw_ [as throw] (errors.dart:251)
    at dio_mixin.dart:628
    at _RootZone.runBinary (zone.dart:1690)
    at _FutureListener.catchError.handleError (future_impl.dart:174)
    at handleError (future_impl.dart:778)
    at Function._propagateToListeners (future_impl.dart:799)
    at _Future.new.[_completeError] (future_impl.dart:609)
    at _SyncCompleter.new.[_completeError] (future_impl.dart:60)
    at _SyncCompleter.new.completeError (future_impl.dart:32)
    at onError (future.dart:544)
    at _RootZone.runBinary (zone.dart:1690)
    at _FutureListener.then.handleError (future_impl.dart:174)
    at handleError (future_impl.dart:778)
    at Function._propagateToListeners (future_impl.dart:799)
    at _Future.new.[_completeError] (future_impl.dart:609)
    at async._AsyncCallbackEntry.new.callback (future_impl.dart:665)
    at Object._microtaskLoop (schedule_microtask.dart:40)
    at _startMicrotaskLoop (schedule_microtask.dart:49)
    at async_patch.dart:166

Answer 1

CORS XMLHttpRequest error 是服务器端错误。它与您的应用程序无关。在使用移动应用程序时，您不会遇到这样的问题，但在 Flutter Web 中这很常见。您可以做什么？- 只需让您的服务器端人员或 api 开发人员启用他/她的项目CORS 策略。几周前我遇到了同样的问题，我问服务器人员然后他从那里启用CORS 但我仍然面临异常然后我问api开发人员然后他从他的django应用程序中启用它并且flutter也不例外网络

Answer 2

这个错误是因为我使用的 Maps Api 不是从客户端代码而是从服务器端调用的。所以解决方案是做一个云函数来发出请求并返回数据

import axios from "axios";

export const serverRequest = functions.https.onCall(async (url, context)=> {
  isAuthenticatedAdmin(context);
  const response = await axios.get(url as string).then(({data})=> data);
  return response;
});