Flutter fromJson - Unhandled error Unhandled error type 'String' is not a subtype of type 'int' occurred in Instance of

Question

I'm using HydratedBloc to try to store color to json as an int value so I don't have a massive if/else method that does a bunch of if (color == Colors.blue) => 'blue' etc...

So I'm trying this:

 int mapColorToInt(Color color) => color.value;

 Color mapIntToColor(int colorValue) => Color(colorValue);

  @override
  ThemeState fromJson(Map<String, dynamic> json) {
    return NewTheme(
      themeData: ThemeData(
        scaffoldBackgroundColor: mapIntToColor(json['scaffoldBackgroundColor']),
        accentColor: mapIntToColor(json['accentColor']),
      ),
    );
  }

  @override
  Map<String, dynamic> toJson(ThemeState state) {
    return {
      'scaffoldBackgroundColor':
          mapColorToInt(state.themeData.scaffoldBackgroundColor),
      'accentColor': mapColorToInt(state.themeData.accentColor),
    };
  }

And get this error:

Unhandled error Unhandled error type 'String' is not a subtype of type 'int' occurred in Instance of 'ThemeBloc'.

Which I don't understand if integer is a supported type, but based on my search it seems I'm not the only one to have issues with integers and json.

So then I tried doing the same thing but keeping it all strings:

 String mapColorToInt(Color color) => color.value.toString();

 Color mapIntToColor(String colorValue) => Color(int.parse(colorValue));

  @override
  ThemeState fromJson(Map<String, dynamic> json) {
    return NewTheme(
      themeData: ThemeData(
        scaffoldBackgroundColor: mapIntToColor(json['scaffoldBackgroundColor']),
        accentColor: mapIntToColor(json['accentColor']),
      ),
    );
  }

  @override
  Map<String, dynamic> toJson(ThemeState state) {
    return {
      'scaffoldBackgroundColor':
          mapColorToInt(state.themeData.scaffoldBackgroundColor),
      'accentColor': mapColorToInt(state.themeData.accentColor),
    };
  }

And that gives this error:

Unhandled error Unhandled error FormatException: Invalid radix-10 number (at character 1)

Clearly I'm missing something here but its not clear what. I tested the mapIntToColor function in the UI and it works fine when passed a color.value. Any help would be much appreciated.

Thanks.

Answer 1

Please let me know json['accentColor']'s example.

If that json value is like '#FCFDSD', try using below code.

scaffoldBackgroundColor: HexColor(json['scaffoldBackgroundColor']),

class HexColor extends Color {
  static int _getColorFromHex(String hexColor) {
    hexColor = hexColor.toUpperCase().replaceAll('#', '');
    if (hexColor.length == 6) {
      hexColor = 'FF' + hexColor;
    }
    return int.parse(hexColor, radix: 16);
  }

  HexColor(final String hexColor) : super(_getColorFromHex(hexColor));
}