This is the Response

{
    "message": null,
    "data": {
        "items": [
            {
                "dealerId": 634,
                "dealerName": "Test12",
                "dealerCode": "dandasn123"
            },
            {
                "dealerId": 36,
                "dealerName": "Saurabh",
                "dealerCode": "ASDF"
            },
            {
                "dealerId": 38,
                "dealerName": "Muskan",
                "dealerCode": "ASDF"
            },
            {
                "dealerId": 16,
                "dealerName": "Nsj94",
                "dealerCode": "ASDF1234"
            }
        ]
    },
    "type": null
}

This is the Model which I have created using jsonToDart Plugin available in Android Studio

import 'Data.dart';

class DealerDetailsModel {
  DealerDetailsModel({
    this.message,
    this.data,
    this.type,
  });

  DealerDetailsModel.fromJson(dynamic json) {
    message = json['message'];
    data = json['data'] != null ? Data.fromJson(json['data']) : null;
    type = json['type'];
  }
  dynamic message;
  Data? data;
  dynamic type;

  Map<String, dynamic> toJson() {
    final map = <String, dynamic>{};
    map['message'] = message;
    if (data != null) {
      map['data'] = data?.toJson();
    }
    map['type'] = type;
    return map;
  }
}

import 'Items.dart';

class Data {
  Data({
    this.items,
  });

  Data.fromJson(dynamic json) {
    if (json['items'] != null) {
      items = [];
      json['items'].forEach((v) {
        items?.add(Items.fromJson(v));
      });
    }
  }
  List<Items>? items;

  Map<String, dynamic> toJson() {
    final map = <String, dynamic>{};
    if (items != null) {
      map['items'] = items?.map((v) => v.toJson()).toList();
    }
    return map;
  }
}

class Items {
  Items({
    this.dealerId,
    this.dealerName,
    this.dealerCode,
  });

  Items.fromJson(dynamic json) {
    dealerId = json['dealerId'];
    dealerName = json['dealerName'];
    dealerCode = json['dealerCode'];
  }
  int? dealerId;
  String? dealerName;
  String? dealerCode;

  Map<String, dynamic> toJson() {
    final map = <String, dynamic>{};
    map['dealerId'] = dealerId;
    map['dealerName'] = dealerName;
    map['dealerCode'] = dealerCode;
    return map;
  }
}

and this is the method that I have created to fetch dealer details, and here only I am facing the error where I have written getData as List

Future<List<DealerDetailsModel>> getDealerDetails() async {
    var params = {'': ''};
    if (isNetworkAvail) {
      await apiBaseHelper.getAPICall(getDealerDetailsData, params).then(
            (getData) async => {
              dealerData = (getData as List)
                  .map((data) => DealerDetailsModel.fromJson(data))
                  .toList(),
            },
          );
    }
    return dealerData;
  }

CodePudding user response：

Your issue is that you are expect a list from api response but it is a Map. So you need to parse it like this. Change your getDealerDetails to this:

Future<DealerDetailsModel?> getDealerDetails() async {
    var params = {'': ''};
    if (isNetworkAvail) {
      var getData = await apiBaseHelper.getAPICall(getDealerDetailsData, params);
   
      return DealerDetailsModel.fromJson(getData);
    }
    return null;
  }

remember change your FutureBuilder's type to DealerDetailsModel? instead of List<DealerDetailsModel>.