type 'Null' is not a subtype of type 'String' when get data-CodePudding

I have a response in JSON:

{
    "data": {
        "id": "12-43-abc",
        "number": "4",
        "name": "Admin Test 1",
        "stage": "active",
        "sex": "female",
        "title": "admin",
        "dob": null,
        "phoneNumber": "1",
        "email": "[email protected]",
        "address": null,
        "mId": null,
        "createdDateTime": "2020-09-17T02:42:10.447Z",
        "totalRemain": null,
        "carryOverRemain": null,
        "fromTime": null,
        "toTime": null
    }
}

To convert JSON to Object, I create a model:

class User {
  String? id;
  String? number;
  String? name;
  String? stage;
  String? sex;
  String? title;
  DateTime? dob;
  String? phoneNumber;
  String? email;
  String? address;
  String? mId;
  DateTime? createdDateTime;
  int? totalRemain;
  int? carryOverRemain;
  DateTime? fromTime;
  DateTime? toTime;

  User({
      this.id,
      this.number,
      this.name,
      this.stage,
      this.sex,
      this.title,
      this.dob,
      this.phoneNumber,
      this.email,
      this.address,
      this.mId,
      this.createdDateTime,
      this.totalRemain,
      this.carryOverRemain,
      this.fromTime,
      this.toTime});

  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      id: json['id'],
      number: json['badgeNumber'] ?? "null",
      name: json['name'] ?? "null",
      stage: json['status'],
      sex: json['gender'] ?? "null",
      title: json['title'] ?? "null",
      dob: DateTime.parse(json['birthDay']),
      phoneNumber: json['phone'] ?? "null",
      email: json['email'] ?? "null",
      address: json['address'] ?? "null",
      mId: json['managerId'] ?? "null",
      createdDateTime: DateTime.parse(json['createdDateTime']),
      totalRemain: json['totalRemain'],
      carryOverRemain: json['carryOverRemain'],
      fromTime: DateTime.parse(json['fromTime']),
      toTime: DateTime.parse(json['toTime'])
    );
  }
}

I create a signIn method:

Future<Either<Failure, dynamic>> signIn(String number, String password) async {
    try {
      Map<String, String> bd = {
        'number': number,
        'password': password
      };

      final Response res = await dio.post(Endpoint.signIn, data: bd);

      if(res.statusCode == 200) {
        return Right(User.fromJson(res.data['data']));
      }
      else {
        return Right(res.data['error']);
      }
    }
    catch(e) {
      throw e;
      return Left(SystemFailure());
    }
  }

When debugging, the status code is 200 but it throws an exception type 'Null' is not a subtype of type 'String'. I've searched Google for it but still have no answer. No idea what's wrong in my model class. Thanks for your help.

CodePudding user response：

The problem is with dob, fromTime and toTime because they are null. You can't do DateTime.parse() on null. So maybe you can replace this

toTime: DateTime.parse(json['toTime'])

with

toTime: json['toTime'] != null ? DateTime.parse(json['toTime']) : null

for example. The same logic with dob and toTime. Probably also with createdDateTime in case that one happens to be null as well

CodePudding user response：

you need to decode the JSON like this:

final decodedJson = json.decode(res);

because the JSON you got from the HTTP request is just a String you need to decode it to get the Map<String, String> the, work with it.