I have a data that I pulled from json. I want to receive and process this data in the following format. When I try manually, I get the error with the actual service data while getting the output I want. My manual attempt:

void main(List<String> args) {
  final map = <Map<String, dynamic>>[
    {'MAH_ID': 10, 'MAH_AD': 'AŞAĞI', 'ILCE_ID': 1, 'ILCE_AD': 'SARI'},
    {'MAH_ID': 11, 'MAH_AD': 'YUKARI', 'ILCE_ID': 1, 'ILCE_AD': 'SARI'},
    {'MAH_ID': 12, 'MAH_AD': 'SAĞ', 'ILCE_ID': 1, 'ILCE_AD': 'SARI'},
    {'MAH_ID': 13, 'MAH_AD': 'SOL', 'ILCE_ID': 1, 'ILCE_AD': 'SARI'},
    {'MAH_ID': 14, 'MAH_AD': 'LOW', 'ILCE_ID': 2, 'ILCE_AD': 'KIRMIZI'},
    {'MAH_ID': 15, 'MAH_AD': 'MİD', 'ILCE_ID': 2, 'ILCE_AD': 'KIRMIZI'},
    {'MAH_ID': 16, 'MAH_AD': 'HİGH', 'ILCE_ID': 2, 'ILCE_AD': 'KIRMIZI'},
    {'MAH_ID': 17, 'MAH_AD': 'ULTRAHİGH', 'ILCE_ID': 2, 'ILCE_AD': 'KIRMIZI'}
  ];

  final mappedValues = <Map<String, List<dynamic>>>[];

  for (final element in map) {
    final ilceAd = element['ILCE_AD'];
    final mahAd = element['MAH_AD'];

    final contains =
        mappedValues.where((e) => e.keys.contains(ilceAd)).toList();

    if (contains.isNotEmpty) {
      if (contains.first.isNotEmpty) {
        if (contains.first.containsKey(ilceAd)) {
          contains.first[ilceAd]!.add(mahAd);
        }
      }
    } else {
      mappedValues.add({
        ilceAd as String: [mahAd]
      });
    }
  }

  print(mappedValues);
}

success output {SARI: [AŞAĞI, YUKARI, SAĞ, SOL]}, {KIRMIZI: [LOW, MİD, HİGH, ULTRAHİGH]}]

my model class

import 'dart:convert';

List<Mahalle> mahalleFromJson(String str) =>
    List<Mahalle>.from(json.decode(str).map((x) => Mahalle.fromJson(x)));

String mahalleToJson(List<Mahalle> data) =>
    json.encode(List<dynamic>.from(data.map((x) => x.toJson())));

class Mahalle {
  Mahalle({
    this.mahId,
    this.mahAdi,
    this.mahIdDbb,
    this.ilceId,
    this.ilceAdi,
    this.ilceIdDbb,
  });

  int? mahId;
  String? mahAdi;
  int? mahIdDbb;
  int? ilceId;
  String? ilceAdi;
  int? ilceIdDbb;

  factory Mahalle.fromJson(Map<String, dynamic> json) => Mahalle(
        mahId: json["MAH_ID"],
        mahAdi: json["MAH_ADI"],
        mahIdDbb: json["MAH_ID_DBB"],
        ilceId: json["ILCE_ID"],
        ilceAdi: json["ILCE_ADI"],
        ilceIdDbb: json["ILCE_ID_DBB"],
      );

  Map<String, dynamic> toJson() => {
        "MAH_ID": mahId,
        "MAH_ADI": mahAdi,
        "MAH_ID_DBB": mahIdDbb,
        "ILCE_ID": ilceId,
        "ILCE_ADI": ilceAdi,
        "ILCE_ID_DBB": ilceIdDbb,
      };
}

method where i pull json data

Future getApiData() async {
    try {
      final response = await http.get(url);
      if (response.statusCode == 200) {
        var result =
            mahalleFromJson(response.body).cast<Map<String, dynamic>>();

        final mappedValues = <Map<String, List<dynamic>>>[];

        for (final element in result) {
          final ilceAd = element['ilceAdi'];
          final mahAd = element["mahAdi"];

          final contains = mappedValues
              .where((element) => element.keys.contains(ilceAd))
              .toList();

          if (contains.isNotEmpty) {
            if (contains.first.isNotEmpty) {
              if (contains.first.containsKey(ilceAd)) {
                contains.first[ilceAd]!.add(mahAd);
              }
            }
          } else {
            mappedValues.add({
              ilceAd as String: [mahAd]
            });
          }
        }
        print(mappedValues);
}

the error i got: type 'Mahalle' is not a subtype of type 'Map<String, dynamic>' in type cast

Thanks in advance for your help

CodePudding user response：

element in your for loop is an Mahalle Item, so if you want to access ilceAd or mahAd you should do this:

var result = mahalleFromJson(response.body); //<--- change this

final mappedValues = <Map<String, List<dynamic>>>[];

for (final element in result) {
          final ilceAd = element.ilceAdi; //<--- change this
          final mahAd = element.mahAdi; //<--- change this

          final contains = mappedValues
              .where((element) => element.keys.contains(ilceAd))
              .toList();

          if (contains.isNotEmpty) {
            if (contains.first.isNotEmpty) {
              if (contains.first.containsKey(ilceAd)) {
                contains.first[ilceAd]!.add(mahAd);
              }
            }
          } else {
            mappedValues.add({
              ilceAd as String: [mahAd]
            });
          }
        }