_TypeError (type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>') in flutter

Question

Hello I am making an api call where I am getting array of banners. I am getting below error -

_TypeError (type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>')

banners_bloc.dart

class BannersBloc {
  late BannerRepository _bannerRepository;
  late StreamController _streamController;

  StreamSink get bannerListSink => _streamController.sink;

  BannersBloc() {
    _streamController = StreamController();
    _bannerRepository = BannerRepository();
    fetchBanners();
  }

  fetchBanners() async {
    bannerListSink.add('Fetching Banners');
    try {
      Banners banners = await _bannerRepository.getBanners();
      bannerListSink.add(banners);
    } catch (e) {
      bannerListSink.add(e.toString());
      print(e);
    }
  }

  dispose() {
    _streamController.close();
  }
}

banners.dart

class Banners {
  late String bannerImageUrl;
  late String bannerImageAlt;
  late bool isActive;
  late int order;
  late String id;

  Banners(
      {required this.bannerImageUrl,
      required this.bannerImageAlt,
      required this.isActive,
      required this.order,
      required this.id});

  Banners.fromJson(Map<String, dynamic> json) {
    bannerImageUrl = json['bannerImageUrl'];
    bannerImageAlt = json['bannerImageAlt'];
    isActive = json['isActive'];
    order = json['order'];
    id = json['id'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['bannerImageUrl'] = this.bannerImageUrl;
    data['bannerImageAlt'] = this.bannerImageAlt;
    data['isActive'] = this.isActive;
    data['order'] = this.order;
    data['id'] = this.id;
    return data;
  }
}

api_base_helper.dart

class APIHelper {
  final String _baseURL =
      "https://raw.githubusercontent.com/gautam-in/shopping-cart-assignment/master/server/";

  Future<dynamic> get(String url) async {
    try {
      final response = await http.get(Uri.parse(_baseURL + url));
      return json.decode(response.body);
    } catch (err) {
      throw new Exception("Something went wrong");
    }
  }
}

get_banners.dart

class BannerRepository {
  Future getBanners() async {
    final response = await new APIHelper().get("banners/index.get.json");
    return Banners.fromJson(response);
  }
}

Does this answer your question? Error: List<dynamic> is not a subtype of type Map<String, dynamic> — anirudh
– anirudh, Commented Jun 30, 2021 at 6:06

Rohan Thacker · Accepted Answer · 2021-06-30 06:19:21Z

2

If your response from the API is a List of Banners, then the error is being thrown by getBanners. As the fromJson method is expecting a of type Map<String, dynamic>. To solve this you'll need to iterate through the response and call Banners.fromJson for each item in the response list.

class BannerRepository {
  Future<List<Banners>> getBanners() async {
    final response = await new APIHelper().get("banners/index.get.json");
   // Sample Code, handler errors and other stuff
    return response.map((e) =>Banners.fromJson(e)).toList();
  }
}

edited Jun 30, 2021 at 6:19

answered Jun 30, 2021 at 6:07

Rohan Thacker

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7 Comments

Rohan Thacker Over a year ago

Where is your error arising from? Paste the full error, so we can track down the error correctly

N Sharma Over a year ago

this line return response.map((e) => Banners.fromJson(response)).toList(); flutter: type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>'

Rohan Thacker Over a year ago

My Mistake, it should be e not response. Updated the code block

N Sharma Over a year ago

after iterating this map now, going flow to pojo class in the fromJson, then after iteration it is giving same error.

Rohan Thacker Over a year ago

Update your question, Include the exact line number and the file where the error occurs.

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