I am using Flutter with Riverpod and have a utility class MapServices that relies on Ref to access state providers. I’m trying to use this class within a ConsumerStatefulWidget, but I’m encountering a type cast error.

Detailed Description:

I have a utility class MapServices that looks like this:

class MapServices {
  final Ref ref;

  const MapServices({required this.ref});

  Future<List<AutoCompleteResult>> searchPlaces(String searchInput) async {
    final String url =
        'https://maps.googleapis.com/maps/api/place/autocomplete/json?input=$searchInput&key=${ref.read(googleMapsApiKey)}';

    var response = await http.get(Uri.parse(url));
    var json = convert.jsonDecode(response.body);
    debugPrint("AutoComplete JSON Results ==> ${json.toString()}");
    var results = json['predictions'] as List;
    return results.map((e) => AutoCompleteResult.fromJson(e)).toList();
  }

  Future<String?> getDistance({required String destination, required String origin}) async {
    try {
      final String url =
          'https://maps.googleapis.com/maps/api/distancematrix/json?destinations=$destination&origins=$origin&units=metric&key=${ref.read(googleMapsApiKey)}';
      final response = await http.get(Uri.parse(url));
      debugPrint(response.body);
      if (response.statusCode == 200) {
        return response.body;
      }
    } catch (e) {
      debugPrint(e.toString());
    }
    return null;
  }
}

In my UI, I have a ConsumerStatefulWidget where I try to use the MapServices class. Here’s how I’m attempting to call the getDistance method on a button tap:

class MyConsumerStatefulWidget extends ConsumerStatefulWidget {
  @override
  _MyConsumerStatefulWidgetState createState() => _MyConsumerStatefulWidgetState();
}

class _MyConsumerStatefulWidgetState extends ConsumerState<MyConsumerStatefulWidget> {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return Scaffold(
      body: Center(
        child: ElevatedButton(
          onPressed: () async {
            try {
              String? distance = await MapServices(ref: ref).getDistance(
                origin:
                    '${ref.watch(originSelectedProvider).coordinates.latitude},${ref.watch(originSelectedProvider).coordinates.longitude}',
                destination:
                    '${ref.watch(destinationSelectedProvider).coordinates.latitude},${ref.watch(destinationSelectedProvider).coordinates.longitude}'
              );
              // Handle distance
            } catch (e) {
              debugPrint('Error: $e');
            }
          },
          child: Text('Get Distance'),
        ),
      ),
    );
  }
}

Problem:
I’m encountering the following error when I run the code and tap the button:

[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: type ‘ConsumerStatefulElement’ is not a subtype of type ‘Ref<Object?>’ in type cast

What I Tried:

• I used the ref parameter from the build method to instantiate MapServices.
• I attempted to call the getDistance method and expected it to fetch the distance based on the origin and destination coordinates from my providers.
• I looked through the Riverpod documentation and various online resources but couldn’t find a clear solution to this type cast issue.

Expected Outcome:

• I expected to pass the ref object directly to MapServices and access the state required to make API calls without encountering type casting errors. My goal was to successfully call the getDistance method and get the result based on the state provided by Riverpod.

Actual Result:

• Instead, I received a type casting error, indicating that the ConsumerStatefulElement (the type of ref object passed) could not be cast to Ref<Object?>.

Request:

• Could you help me understand how to correctly pass the Ref from a ConsumerStatefulWidget to a class like MapServices in Riverpod? Is there a specific way to handle the Ref object within the ConsumerStatefulWidget context that I’m missing? Any guidance or code examples would be greatly appreciated.

Additional Context:

• I’m using the Riverpod package for state management.
• My goal is to access the state provided by Riverpod and use it to call APIs within MapServices.
• Any insights into the proper usage of Ref within ConsumerStatefulWidget would be appreciated.
  Thank you for your help!