I want to save list item with future bool is it possible?

Question

Future<bool> login({username, password}) async {
    var api = API();
    _status = LoginStatus.loading;
    notifyListeners();
    var url = Uri.parse(api.baseUrl + api.auth);
    final response = await http.post(
      url,
      body: jsonEncode({
        "identifier": "$username",
        "password": "$password",
      }),
      headers: <String, String>{
        'Content-Type': 'application/json; charset=UTF-8',
      },
    );
    if (response.statusCode == 200) {
      final parsed = jsonDecode(response.body).cast<Map<String, dynamic>>();
      parsed
          .map<UserModel>((json) => UserModel.fromJson(json))
          .toList();
      final token = jsonDecode(response.body)['jwt'];
      print(token);
      await saveToken(token);
      return true;
    } else {
      _status = LoginStatus.error;
      _error = response.body;
      notifyListeners();
      return false;
    }
  }

Code Screen Shot

How Should I save this parsed JSON to UserModel? I have encountered many problems and figured out many things on my own but I am not yet able to add data to the model.

By the way I am using strapi as a back end and every api is working. And I amso use a website called json to dart converter so that my models are correct(As I Assume).

Please help !!!!!!!!!!!!

UserModel

class UserModel {
  User user;

  UserModel({this.user});

  UserModel.fromJson(Map<String, dynamic> json) {
    user = json['user'] != null ? new User.fromJson(json['user']) : null;
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this.user != null) {
      data['user'] = this.user.toJson();
    }
    return data;
  }
}

class User {
  int id;
  String username;
  String email;
  String provider;
  bool confirmed;
  bool blocked;
  Role role;
  String displayName;
  String createdAt;
  String updatedAt;
  Avatar avatar;
  List<UserCategories> userCategories;

  User(
      {this.id,
      this.username,
      this.email,
      this.provider,
      this.confirmed,
      this.blocked,
      this.role,
      this.displayName,
      this.createdAt,
      this.updatedAt,
      this.avatar,
      this.userCategories});

  User.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    username = json['username'];
    email = json['email'];
    provider = json['provider'];
    confirmed = json['confirmed'];
    blocked = json['blocked'];
    role = json['role'] != null ? new Role.fromJson(json['role']) : null;
    displayName = json['displayName'];
    createdAt = json['created_at'];
    updatedAt = json['updated_at'];
    avatar =
        json['avatar'] != null ? new Avatar.fromJson(json['avatar']) : null;
    if (json['user_categories'] != null) {
      userCategories = new List<UserCategories>();
      json['user_categories'].forEach((v) {
        userCategories.add(new UserCategories.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['username'] = this.username;
    data['email'] = this.email;
    data['provider'] = this.provider;
    data['confirmed'] = this.confirmed;
    data['blocked'] = this.blocked;
    if (this.role != null) {
      data['role'] = this.role.toJson();
    }
    data['displayName'] = this.displayName;
    data['created_at'] = this.createdAt;
    data['updated_at'] = this.updatedAt;
    if (this.avatar != null) {
      data['avatar'] = this.avatar.toJson();
    }
    if (this.userCategories != null) {
      data['user_categories'] =
          this.userCategories.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

class Role {
  int id;
  String name;
  String description;
  String type;

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

  Role.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    name = json['name'];
    description = json['description'];
    type = json['type'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['name'] = this.name;
    data['description'] = this.description;
    data['type'] = this.type;
    return data;
  }
}

class Avatar {
  int id;
  String name;
  String alternativeText;
  String caption;
  int width;
  int height;
  Formats formats;
  String hash;
  String ext;
  String mime;
  double size;
  String url;
  Null previewUrl;
  String provider;
  Null providerMetadata;
  String createdAt;
  String updatedAt;

  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});

  Avatar.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    name = json['name'];
    alternativeText = json['alternativeText'];
    caption = json['caption'];
    width = json['width'];
    height = json['height'];
    formats =
        json['formats'] != null ? new Formats.fromJson(json['formats']) : null;
    hash = json['hash'];
    ext = json['ext'];
    mime = json['mime'];
    size = json['size'];
    url = json['url'];
    previewUrl = json['previewUrl'];
    provider = json['provider'];
    providerMetadata = json['provider_metadata'];
    createdAt = json['created_at'];
    updatedAt = json['updated_at'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['name'] = this.name;
    data['alternativeText'] = this.alternativeText;
    data['caption'] = this.caption;
    data['width'] = this.width;
    data['height'] = this.height;
    if (this.formats != null) {
      data['formats'] = this.formats.toJson();
    }
    data['hash'] = this.hash;
    data['ext'] = this.ext;
    data['mime'] = this.mime;
    data['size'] = this.size;
    data['url'] = this.url;
    data['previewUrl'] = this.previewUrl;
    data['provider'] = this.provider;
    data['provider_metadata'] = this.providerMetadata;
    data['created_at'] = this.createdAt;
    data['updated_at'] = this.updatedAt;
    return data;
  }
}

class Formats {
  Thumbnail thumbnail;

  Formats({this.thumbnail});

  Formats.fromJson(Map<String, dynamic> json) {
    thumbnail = json['thumbnail'] != null
        ? new Thumbnail.fromJson(json['thumbnail'])
        : null;
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this.thumbnail != null) {
      data['thumbnail'] = this.thumbnail.toJson();
    }
    return data;
  }
}

class Thumbnail {
  String name;
  String hash;
  String ext;
  String mime;
  int width;
  int height;
  double size;
  Null path;
  String url;

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

  Thumbnail.fromJson(Map<String, dynamic> json) {
    name = json['name'];
    hash = json['hash'];
    ext = json['ext'];
    mime = json['mime'];
    width = json['width'];
    height = json['height'];
    size = json['size'];
    path = json['path'];
    url = json['url'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['name'] = this.name;
    data['hash'] = this.hash;
    data['ext'] = this.ext;
    data['mime'] = this.mime;
    data['width'] = this.width;
    data['height'] = this.height;
    data['size'] = this.size;
    data['path'] = this.path;
    data['url'] = this.url;
    return data;
  }
}

class UserCategories {
  int id;
  String categoryName;
  int usersPermissionsUser;
  String publishedAt;
  String createdAt;
  String updatedAt;

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

  UserCategories.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    categoryName = json['categoryName'];
    usersPermissionsUser = json['users_permissions_user'];
    publishedAt = json['published_at'];
    createdAt = json['created_at'];
    updatedAt = json['updated_at'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['categoryName'] = this.categoryName;
    data['users_permissions_user'] = this.usersPermissionsUser;
    data['published_at'] = this.publishedAt;
    data['created_at'] = this.createdAt;
    data['updated_at'] = this.updatedAt;
    return data;
  }
}

Answer 1

The UserModel.fromJson method will only work if the response.body content is a User, so to fix your issue, instead of using UserModel.fromJson on the response.body json decoded variable, rather use the fromJson() function on data that you are sure will conform to your class definition.

For example:

class User{
  final String name;
  final String surname;
  final String email;

  User({this.name, this.surname, this.email});

  factory User.fromJson(Map<String,dynamic> json){
    return User(
      'name': json['name'],
      'surname': json['surname'],
      'email': json['email'] 
    );
  }
}

The json response that is recieved from the api:

{
  "name" : "John",
  "surname": "Smith",
  "email": "johnsmith@mail.com"
}

In your function, decode response and cast to the User model class:

final parsed = jsonDecode(response.body);  // or Map<String,dynamic> parsed = jsonDecode(response.body);
User user = User.fromJson(parsed)