onRequest method

@override Future onRequest(RequestOptions options)

The callback will be executed before the request is initiated.

If you want to resolve the request with some custom data， you can return a Response object or return dio.resolve. If you want to reject the request with a error message, you can return a DioError object or return dio.reject . If you want to continue the request, return the Options object.

 Future onRequest(RequestOptions options) => dio.resolve('fake data');
 ...
 print(response.data) // 'fake data';

Implementation

@override
Future onRequest(RequestOptions options) async {
  if (_onRequest != null) {
    return _onRequest!(options);
  }
}