CODEWITHSUNDEEP
jsonflutterdart
Nikita
Nikita

Reputation: 765

Flutter json_serializable error: Unhandled Exception: type 'Null' is not a subtype of type 'String' in type cast

Im having the problem above, I understand that in my data some things are null for example the leistungData from Diesel doesn't contain anything, so the title is null:

                "title":"Benzin",
                "leistungData":[
                   {
                      "title":"240 PS"
                   }
                ]
             },
             {
                "title":"Diesel",
                "leistungData":[
                   
                ]
             },

So I get that I get the 'Null' is not a subtype of type 'String'. But how can I change my code below so that I can keep this Json structure?

    import 'leistungData.dart';


part 'treibstoffData.g.dart';

@JsonSerializable(explicitToJson: true)
class TreibstoffData {
  final String title;
  final List <LeistungData> leistungData;

  TreibstoffData(this.title, this.leistungData);

  factory TreibstoffData.fromJson(Map<String, dynamic> json)
  => _$TreibstoffDataFromJson(json);
  Map<String, dynamic> toJson() => _$TreibstoffDataToJson(this);
}

& here the LeistungData:

    import 'package:json_annotation/json_annotation.dart';

import 'unterscheidungsData.dart';

part 'leistungData.g.dart';

@JsonSerializable()
class LeistungData {
  final String title;

  LeistungData(this.title);

  factory LeistungData.fromJson(Map<String, dynamic> json)
  => _$LeistungDataFromJson(json);
  Map<String, dynamic> toJson() => _$LeistungDataToJson(this);
}

I hope I was clear and didn't forget anything, just write to me if Im missing something

Upvotes: 0

Views: 551

Answers (1)

Md. Yeasin Sheikh
Md. Yeasin Sheikh

Reputation: 63559

convert to nullable list.

replace final List <LeistungData> leistungData; with final List <LeistungData>? leistungData; also try final String? title ; let me know if it fails to solve the error.

Upvotes: 1

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