Flutter JSON Array Parsing getting error : Exception: type '(dynamic) => xxx is not a subtype of type '(Map) => List' of 'f'

Question

Sorry if It's repeated the question but I didn't found a solution.

Error:

Exception: type '(dynamic) => PostalModel' is not a subtype of type '(Map<String, dynamic>) => List' of 'f'

What I have done:

1. Calling API:

   Future<PostalModel> fetchPhotos(http.Client client) async {
      final response =
       await client.get('https://api.postalpincode.in/pincode/364710');
   
      // Use the compute function to run parsePhotos in a separate isolate.
      return compute(parsePostalPincode, response.body);
   }
   

2. parsing JSON:

    // A function that converts a response body into a List.
    PostalModel parsePostalPincode(String responseBody) {
      print(responseBody);
      final parsed = jsonDecode(responseBody).cast<Map<String, dynamic>>();
      print('Parsed : $parsed'); //Getting Log OUTPUT
      PostalModel postalModel = parsed.map<List<PostalModel>>((json) => PostalModel.fromJson(json));
      print('Postal Model : $postalModel'); //Getting Log OUTPUT
      return postalModel;
    }
   

3. Binding Data in body:

   body: FutureBuilder<PostalModel>(
     future: fetchPhotos(http.Client()),
     builder: (context, snapshot) {
       print('snapshot $snapshot'); // Getting Error Here
       // "AsyncSnapshot<PostalModel>(ConnectionState.done, null, Exception: type '(dynamic) => PostalModel' is not a subtype of type '(Map<String, dynamic>) => List<PostalModel>' of 'f')"
       if (snapshot.hasError) print(snapshot.error);
   
       return snapshot.hasData
          ? PostOfficeList(postOfficeList: snapshot.data.postOffice)
          : Center(child: CircularProgressIndicator());
     },
   ),
   

You can check JSON from API Link and I have created a Model class from here.

Answer 1

And finally, I got succeed with the following solution:

// A function that converts a response body into a List.
PostalModel parsePostalPincode(String responseBody) {
  final parsed = jsonDecode(responseBody).cast<Map<String, dynamic>>();
  print('Parsed : $parsed[0]'); 
  PostalModel postalModel = PostalModel.fromJson(parsed[0]);
  print('Postal Model : $postalModel');
  return postalModel;
}

Flutter is so crazy for a newbie. :P