Parsing JSON in flutter cast<RK, RV>() => Map<RK, RV>, No such method error

Question

Future<List<CurrentUser>> getCurrUserSettings() async {
int id = await getCurrentUser();
print(id);
final _storage = FlutterSecureStorage();
_token = await _storage.read(key: "token");
var api = API();
// TODO resolve id so that we have it on the start and not called everytime
String newUrl = "${api.baseUrl}${api.cuUser}$id";
var url = Uri.parse(newUrl);
var response = await http.get(
  url,
  headers: <String, String>{
    'Content-Type': 'application/json; charset=UTF-8',
    'Authorization': "Bearer $_token",
  },
);
if (response.statusCode == 200) {
  final parsed = jsonDecode(response.body).cast<Map<String, dynamic>>();
  return parsed
      .map<CurrentUser>((json) => CurrentUser.fromJson(json))
      .toList();
} else {
  print(response.statusCode);
}
return null; }

This is the code I am using to call current user data. This function returns a list. I have made many other API calls with the same technique and all of them are working perfectly fine but only in this method I am getting the following error.

E/flutter (14954): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: NoSuchMethodError: Class '_InternalLinkedHashMap<String, dynamic>' has no instance method 'cast' with matching arguments.
E/flutter (14954): Receiver: _LinkedHashMap len:16
E/flutter (14954): Tried calling: cast<Map<String, dynamic>>()
E/flutter (14954): Found: cast<RK, RV>() => Map<RK, RV>
E/flutter (14954): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)
E/flutter (14954): #1      AuthService.getCurrUserSettings
package:App/…/Services/Auth.dart:73
E/flutter (14954): <asynchronous suspension>
E/flutter (14954): #2      DrawerUserInfo.getUserInfo
package:App/…/components/drawerProvider.dart:10
E/flutter (14954): <asynchronous suspension>

I am also sharing the model file too please take a look. I am stuck with this for a while I have used many different models and the error is same in every model.

Response Json

{
"id": 3,
"username": "PlayPizza",
"email": "play@pizza.com",
"provider": "local",
"confirmed": true,
"blocked": null,
"role": {
    "id": 1,
    "name": "Authenticated",
    "description": "Default role given to authenticated user.",
    "type": "authenticated"
},
"displayName": "PlayPizza",
"user_information": {
    "id": 1,
    "country": "India",
    "state": "Delhi",
    "address": "Some address",
    "postalcode": "110092",
    "users_permissions_user": 3,
    "published_at": "2021-07-04T21:24:46.324Z",
    "created_at": "2021-07-04T21:24:43.063Z",
    "updated_at": "2021-07-04T21:24:46.409Z",
    "certificate": {
        "id": 1,
        "name": "1_9cb3b3b033.jpg",
        "alternativeText": "",
        "caption": "",
        "width": 300,
        "height": 300,
        "formats": {
            "thumbnail": {
                "ext": ".jpg",
                "url": "/uploads/thumbnail_1_9cb3b3b033_7980eea4f5.jpg",
                "hash": "thumbnail_1_9cb3b3b033_7980eea4f5",
                "mime": "image/jpeg",
                "name": "thumbnail_1_9cb3b3b033.jpg",
                "path": null,
                "size": 2.48,
                "width": 156,
                "height": 156
            }
        },
        "hash": "1_9cb3b3b033_7980eea4f5",
        "ext": ".jpg",
        "mime": "image/jpeg",
        "size": 5.28,
        "url": "/uploads/1_9cb3b3b033_7980eea4f5.jpg",
        "previewUrl": null,
        "provider": "local",
        "provider_metadata": null,
        "created_at": "2021-07-04T15:03:55.744Z",
        "updated_at": "2021-07-04T15:03:55.798Z"
    }
},
"feedback": "hello",
"created_at": "2021-07-04T19:59:30.024Z",
"updated_at": "2021-07-04T21:26:41.314Z",
"avatar": {
    "id": 10,
    "name": "customer_3_008140d19d.png",
    "alternativeText": "",
    "caption": "",
    "width": 180,
    "height": 180,
    "formats": {
        "thumbnail": {
            "ext": ".png",
            "url": "/uploads/thumbnail_customer_3_008140d19d_a96cc0a5e3.png",
            "hash": "thumbnail_customer_3_008140d19d_a96cc0a5e3",
            "mime": "image/png",
            "name": "thumbnail_customer_3_008140d19d.png",
            "path": null,
            "size": 62.71,
            "width": 156,
            "height": 156
        }
    },
    "hash": "customer_3_008140d19d_a96cc0a5e3",
    "ext": ".png",
    "mime": "image/png",
    "size": 65.81,
    "url": "/uploads/customer_3_008140d19d_a96cc0a5e3.png",
    "previewUrl": null,
    "provider": "local",
    "provider_metadata": null,
    "created_at": "2021-07-04T17:59:44.000Z",
    "updated_at": "2021-07-04T17:59:44.024Z"
},
"user_categories": [
    {
        "id": 1,
        "categoryName": "GymGoer",
        "users_permissions_user": 3,
        "published_at": "2021-07-04T15:53:43.824Z",
        "created_at": "2021-07-04T15:53:39.228Z",
        "updated_at": "2021-07-04T21:26:41.307Z"
    }
],
"workoutplaces": [
    {
        "id": 2,
        "title": "Gym Nation",
        "description": "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.",
        "location": "145 Marlee Ave, York, ON M6B 3H3, Canada",
        "price": 88.26,
        "rating": 4.5,
        "latitude": 43.80946617910369,
        "longitude": -79.26975142707997,
        "users_permissions_user": 3,
        "published_at": "2021-07-04T17:09:53.162Z",
        "created_at": "2021-07-04T17:09:50.238Z",
        "updated_at": "2021-07-04T21:26:41.308Z",
        "coverimg": {
            "id": 8,
            "name": "large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3.jpg",
            "alternativeText": "",
            "caption": "",
            "width": 1000,
            "height": 666,
            "formats": {
                "small": {
                    "ext": ".jpg",
                    "url": "/uploads/small_large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3_fe08736916.jpg",
                    "hash": "small_large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3_fe08736916",
                    "mime": "image/jpeg",
                    "name": "small_large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3.jpg",
                    "path": null,
                    "size": 27.34,
                    "width": 500,
                    "height": 333
                },
                "medium": {
                    "ext": ".jpg",
                    "url": "/uploads/medium_large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3_fe08736916.jpg",
                    "hash": "medium_large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3_fe08736916",
                    "mime": "image/jpeg",
                    "name": "medium_large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3.jpg",
                    "path": null,
                    "size": 48.79,
                    "width": 750,
                    "height": 500
                },
                "thumbnail": {
                    "ext": ".jpg",
                    "url": "/uploads/thumbnail_large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3_fe08736916.jpg",
                    "hash": "thumbnail_large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3_fe08736916",
                    "mime": "image/jpeg",
                    "name": "thumbnail_large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3.jpg",
                    "path": null,
                    "size": 9.3,
                    "width": 234,
                    "height": 156
                }
            },
            "hash": "large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3_fe08736916",
            "ext": ".jpg",
            "mime": "image/jpeg",
            "size": 74.23,
            "url": "/uploads/large_sule_makaroglu_Y_Fmvj_O3_TP_s_unsplash_c546ce68c3_fe08736916.jpg",
            "previewUrl": null,
            "provider": "local",
            "provider_metadata": null,
            "created_at": "2021-07-04T17:05:47.094Z",
            "updated_at": "2021-07-04T17:05:47.104Z"
        }
    }
],
"upcomming_classes": [
    {
        "id": 1,
        "name": "Yoga house",
        "description": "Some Description",
        "date": "2021-07-13",
        "time": "01:30:00",
        "confirmed": true,
        "paid": true,
        "price": 59.33,
        "workoutplace": 1,
        "users_permissions_user": 3,
        "month": "July",
        "published_at": null,
        "created_at": "2021-07-04T21:26:23.276Z",
        "updated_at": "2021-07-04T21:26:41.309Z"
    }
]}

Model File

import 'dart:convert';

CurrentUser currentUserFromJson(String str) =>
    CurrentUser.fromJson(json.decode(str));

String currentUserToJson(CurrentUser data) => json.encode(data.toJson());

class CurrentUser {
  CurrentUser({
    this.id,
    this.username,
    this.email,
    this.provider,
    this.confirmed,
    this.blocked,
    this.role,
    this.displayName,
    this.userInformation,
    this.feedback,
    this.createdAt,
    this.updatedAt,
    this.avatar,
    this.userCategories,
    this.workoutplaces,
    this.upcommingClasses,
  });

  int id;
  String username;
  String email;
  String provider;
  bool confirmed;
  dynamic blocked;
  Role role;
  String displayName;
  UserInformation userInformation;
  String feedback;
  DateTime createdAt;
  DateTime updatedAt;
  Avatar avatar;
  List<UserCategory> userCategories;
  List<Workoutplace> workoutplaces;
  List<UpcommingClass> upcommingClasses;

  factory CurrentUser.fromJson(Map<String, dynamic> json) => CurrentUser(
        id: json["id"],
        username: json["username"],
        email: json["email"],
        provider: json["provider"],
        confirmed: json["confirmed"],
        blocked: json["blocked"],
        role: Role.fromJson(json["role"]),
        displayName: json["displayName"],
        userInformation: UserInformation.fromJson(json["user_information"]),
        feedback: json["feedback"],
        createdAt: DateTime.parse(json["created_at"]),
        updatedAt: DateTime.parse(json["updated_at"]),
        avatar: Avatar.fromJson(json["avatar"]),
        userCategories: List<UserCategory>.from(
            json["user_categories"].map((x) => UserCategory.fromJson(x))),
        workoutplaces: List<Workoutplace>.from(
            json["workoutplaces"].map((x) => Workoutplace.fromJson(x))),
        upcommingClasses: List<UpcommingClass>.from(
            json["upcomming_classes"].map((x) => UpcommingClass.fromJson(x))),
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "username": username,
        "email": email,
        "provider": provider,
        "confirmed": confirmed,
        "blocked": blocked,
        "role": role.toJson(),
        "displayName": displayName,
        "user_information": userInformation.toJson(),
        "feedback": feedback,
        "created_at": createdAt.toIso8601String(),
        "updated_at": updatedAt.toIso8601String(),
        "avatar": avatar.toJson(),
        "user_categories":
            List<dynamic>.from(userCategories.map((x) => x.toJson())),
        "workoutplaces":
            List<dynamic>.from(workoutplaces.map((x) => x.toJson())),
        "upcomming_classes":
            List<dynamic>.from(upcommingClasses.map((x) => x.toJson())),
      };
}

class Avatar {
  Avatar({
    this.id,
    this.name,
    this.alternativeText,
    this.caption,
    this.width,
    this.height,
    this.formats,
    this.hash,
    this.ext,
    this.mime,
    this.size,
    this.url,
    this.previewUrl,
    this.provider,
    this.providerMetadata,
    this.createdAt,
    this.updatedAt,
  });

  int id;
  String name;
  String alternativeText;
  String caption;
  int width;
  int height;
  AvatarFormats formats;
  String hash;
  String ext;
  String mime;
  double size;
  String url;
  dynamic previewUrl;
  String provider;
  dynamic providerMetadata;
  DateTime createdAt;
  DateTime updatedAt;

  factory Avatar.fromJson(Map<String, dynamic> json) => Avatar(
        id: json["id"],
        name: json["name"],
        alternativeText: json["alternativeText"],
        caption: json["caption"],
        width: json["width"],
        height: json["height"],
        formats: AvatarFormats.fromJson(json["formats"]),
        hash: json["hash"],
        ext: json["ext"],
        mime: json["mime"],
        size: json["size"].toDouble(),
        url: json["url"],
        previewUrl: json["previewUrl"],
        provider: json["provider"],
        providerMetadata: json["provider_metadata"],
        createdAt: DateTime.parse(json["created_at"]),
        updatedAt: DateTime.parse(json["updated_at"]),
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "name": name,
        "alternativeText": alternativeText,
        "caption": caption,
        "width": width,
        "height": height,
        "formats": formats.toJson(),
        "hash": hash,
        "ext": ext,
        "mime": mime,
        "size": size,
        "url": url,
        "previewUrl": previewUrl,
        "provider": provider,
        "provider_metadata": providerMetadata,
        "created_at": createdAt.toIso8601String(),
        "updated_at": updatedAt.toIso8601String(),
      };
}

class AvatarFormats {
  AvatarFormats({
    this.thumbnail,
  });

  Thumbnail thumbnail;

  factory AvatarFormats.fromJson(Map<String, dynamic> json) => AvatarFormats(
        thumbnail: Thumbnail.fromJson(json["thumbnail"]),
      );

  Map<String, dynamic> toJson() => {
        "thumbnail": thumbnail.toJson(),
      };
}

class Thumbnail {
  Thumbnail({
    this.ext,
    this.url,
    this.hash,
    this.mime,
    this.name,
    this.path,
    this.size,
    this.width,
    this.height,
  });

  String ext;
  String url;
  String hash;
  String mime;
  String name;
  dynamic path;
  double size;
  int width;
  int height;

  factory Thumbnail.fromJson(Map<String, dynamic> json) => Thumbnail(
        ext: json["ext"],
        url: json["url"],
        hash: json["hash"],
        mime: json["mime"],
        name: json["name"],
        path: json["path"],
        size: json["size"].toDouble(),
        width: json["width"],
        height: json["height"],
      );

  Map<String, dynamic> toJson() => {
        "ext": ext,
        "url": url,
        "hash": hash,
        "mime": mime,
        "name": name,
        "path": path,
        "size": size,
        "width": width,
        "height": height,
      };
}

class Role {
  Role({
    this.id,
    this.name,
    this.description,
    this.type,
  });

  int id;
  String name;
  String description;
  String type;

  factory Role.fromJson(Map<String, dynamic> json) => Role(
        id: json["id"],
        name: json["name"],
        description: json["description"],
        type: json["type"],
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "name": name,
        "description": description,
        "type": type,
      };
}

class UpcommingClass {
  UpcommingClass({
    this.id,
    this.name,
    this.description,
    this.date,
    this.time,
    this.confirmed,
    this.paid,
    this.price,
    this.workoutplace,
    this.usersPermissionsUser,
    this.month,
    this.publishedAt,
    this.createdAt,
    this.updatedAt,
  });

  int id;
  String name;
  String description;
  DateTime date;
  String time;
  bool confirmed;
  bool paid;
  double price;
  int workoutplace;
  int usersPermissionsUser;
  String month;
  dynamic publishedAt;
  DateTime createdAt;
  DateTime updatedAt;

  factory UpcommingClass.fromJson(Map<String, dynamic> json) => UpcommingClass(
        id: json["id"],
        name: json["name"],
        description: json["description"],
        date: DateTime.parse(json["date"]),
        time: json["time"],
        confirmed: json["confirmed"],
        paid: json["paid"],
        price: json["price"].toDouble(),
        workoutplace: json["workoutplace"],
        usersPermissionsUser: json["users_permissions_user"],
        month: json["month"],
        publishedAt: json["published_at"],
        createdAt: DateTime.parse(json["created_at"]),
        updatedAt: DateTime.parse(json["updated_at"]),
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "name": name,
        "description": description,
        "date":
            "${date.year.toString().padLeft(4, '0')}-${date.month.toString().padLeft(2, '0')}-${date.day.toString().padLeft(2, '0')}",
        "time": time,
        "confirmed": confirmed,
        "paid": paid,
        "price": price,
        "workoutplace": workoutplace,
        "users_permissions_user": usersPermissionsUser,
        "month": month,
        "published_at": publishedAt,
        "created_at": createdAt.toIso8601String(),
        "updated_at": updatedAt.toIso8601String(),
      };
}

class UserCategory {
  UserCategory({
    this.id,
    this.categoryName,
    this.usersPermissionsUser,
    this.publishedAt,
    this.createdAt,
    this.updatedAt,
  });

  int id;
  String categoryName;
  int usersPermissionsUser;
  DateTime publishedAt;
  DateTime createdAt;
  DateTime updatedAt;

  factory UserCategory.fromJson(Map<String, dynamic> json) => UserCategory(
        id: json["id"],
        categoryName: json["categoryName"],
        usersPermissionsUser: json["users_permissions_user"],
        publishedAt: DateTime.parse(json["published_at"]),
        createdAt: DateTime.parse(json["created_at"]),
        updatedAt: DateTime.parse(json["updated_at"]),
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "categoryName": categoryName,
        "users_permissions_user": usersPermissionsUser,
        "published_at": publishedAt.toIso8601String(),
        "created_at": createdAt.toIso8601String(),
        "updated_at": updatedAt.toIso8601String(),
      };
}

class UserInformation {
  UserInformation({
    this.id,
    this.country,
    this.state,
    this.address,
    this.postalcode,
    this.usersPermissionsUser,
    this.publishedAt,
    this.createdAt,
    this.updatedAt,
    this.certificate,
  });

  int id;
  String country;
  String state;
  String address;
  String postalcode;
  int usersPermissionsUser;
  DateTime publishedAt;
  DateTime createdAt;
  DateTime updatedAt;
  Avatar certificate;

  factory UserInformation.fromJson(Map<String, dynamic> json) =>
      UserInformation(
        id: json["id"],
        country: json["country"],
        state: json["state"],
        address: json["address"],
        postalcode: json["postalcode"],
        usersPermissionsUser: json["users_permissions_user"],
        publishedAt: DateTime.parse(json["published_at"]),
        createdAt: DateTime.parse(json["created_at"]),
        updatedAt: DateTime.parse(json["updated_at"]),
        certificate: Avatar.fromJson(json["certificate"]),
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "country": country,
        "state": state,
        "address": address,
        "postalcode": postalcode,
        "users_permissions_user": usersPermissionsUser,
        "published_at": publishedAt.toIso8601String(),
        "created_at": createdAt.toIso8601String(),
        "updated_at": updatedAt.toIso8601String(),
        "certificate": certificate.toJson(),
      };
}

class Workoutplace {
  Workoutplace({
    this.id,
    this.title,
    this.description,
    this.location,
    this.price,
    this.rating,
    this.latitude,
    this.longitude,
    this.usersPermissionsUser,
    this.publishedAt,
    this.createdAt,
    this.updatedAt,
    this.coverimg,
  });

  int id;
  String title;
  String description;
  String location;
  double price;
  double rating;
  double latitude;
  double longitude;
  int usersPermissionsUser;
  DateTime publishedAt;
  DateTime createdAt;
  DateTime updatedAt;
  Coverimg coverimg;

  factory Workoutplace.fromJson(Map<String, dynamic> json) => Workoutplace(
        id: json["id"],
        title: json["title"],
        description: json["description"],
        location: json["location"],
        price: json["price"].toDouble(),
        rating: json["rating"].toDouble(),
        latitude: json["latitude"].toDouble(),
        longitude: json["longitude"].toDouble(),
        usersPermissionsUser: json["users_permissions_user"],
        publishedAt: DateTime.parse(json["published_at"]),
        createdAt: DateTime.parse(json["created_at"]),
        updatedAt: DateTime.parse(json["updated_at"]),
        coverimg: Coverimg.fromJson(json["coverimg"]),
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "title": title,
        "description": description,
        "location": location,
        "price": price,
        "rating": rating,
        "latitude": latitude,
        "longitude": longitude,
        "users_permissions_user": usersPermissionsUser,
        "published_at": publishedAt.toIso8601String(),
        "created_at": createdAt.toIso8601String(),
        "updated_at": updatedAt.toIso8601String(),
        "coverimg": coverimg.toJson(),
      };
}

class Coverimg {
  Coverimg({
    this.id,
    this.name,
    this.alternativeText,
    this.caption,
    this.width,
    this.height,
    this.formats,
    this.hash,
    this.ext,
    this.mime,
    this.size,
    this.url,
    this.previewUrl,
    this.provider,
    this.providerMetadata,
    this.createdAt,
    this.updatedAt,
  });

  int id;
  String name;
  String alternativeText;
  String caption;
  int width;
  int height;
  CoverimgFormats formats;
  String hash;
  String ext;
  String mime;
  double size;
  String url;
  dynamic previewUrl;
  String provider;
  dynamic providerMetadata;
  DateTime createdAt;
  DateTime updatedAt;

  factory Coverimg.fromJson(Map<String, dynamic> json) => Coverimg(
        id: json["id"],
        name: json["name"],
        alternativeText: json["alternativeText"],
        caption: json["caption"],
        width: json["width"],
        height: json["height"],
        formats: CoverimgFormats.fromJson(json["formats"]),
        hash: json["hash"],
        ext: json["ext"],
        mime: json["mime"],
        size: json["size"].toDouble(),
        url: json["url"],
        previewUrl: json["previewUrl"],
        provider: json["provider"],
        providerMetadata: json["provider_metadata"],
        createdAt: DateTime.parse(json["created_at"]),
        updatedAt: DateTime.parse(json["updated_at"]),
      );

  Map<String, dynamic> toJson() => {
        "id": id,
        "name": name,
        "alternativeText": alternativeText,
        "caption": caption,
        "width": width,
        "height": height,
        "formats": formats.toJson(),
        "hash": hash,
        "ext": ext,
        "mime": mime,
        "size": size,
        "url": url,
        "previewUrl": previewUrl,
        "provider": provider,
        "provider_metadata": providerMetadata,
        "created_at": createdAt.toIso8601String(),
        "updated_at": updatedAt.toIso8601String(),
      };
}

class CoverimgFormats {
  CoverimgFormats({
    this.small,
    this.medium,
    this.thumbnail,
  });

  Thumbnail small;
  Thumbnail medium;
  Thumbnail thumbnail;

  factory CoverimgFormats.fromJson(Map<String, dynamic> json) =>
      CoverimgFormats(
        small: Thumbnail.fromJson(json["small"]),
        medium: Thumbnail.fromJson(json["medium"]),
        thumbnail: Thumbnail.fromJson(json["thumbnail"]),
      );

  Map<String, dynamic> toJson() => {
        "small": small.toJson(),
        "medium": medium.toJson(),
        "thumbnail": thumbnail.toJson(),
      };
}

Answer 1

the thing is that in your response you don't have a list of the users, you only have one user and you are trying to parse it to a list of the users. So, please replace

final parsed = jsonDecode(response.body).cast<Map<String, dynamic>>();
return parsed
      .map<CurrentUser>((json) => CurrentUser.fromJson(json))
      .toList();

With parsing to single user:

final parsed = json.decode(resource);
final user = CurrentUser.fromJson(parsed);