Generate fromJson code for non valid json type

Question

I am using freezed.

My code looks like this:

import 'package:freezed_annotation/freezed_annotation.dart';

part 'key_state.freezed.dart';
part 'key_state.g.dart';

@freezed
class KeyState with _$KeyState {
  factory KeyState({
    CancelToken? token,
    // ...
  }) = _KeyState;

  factory KeyState.initial() => KeyState();

  factory KeyState.fromJson(Map<String, dynamic> json) =>
      _$KeyStateFromJson(json);
}

This is the CancelToken class from https://github.com/flutterchina/dio/blob/master/dio/lib/src/cancel_token.dart

This does not work.

Errors:

Could not generate `fromJson` code for `token`.
To support the type `CancelToken` you can:
* Use `JsonConverter`
  https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonConverter-class.html
* Use `JsonKey` fields `fromJson` and `toJson`
  https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonKey/fromJson.html
  https://pub.dev/documentation/json_annotation/latest/json_annotation/JsonKey/toJson.html
package:flutter_app/redux/state/key_state.freezed.dart:114:22

How do I do this?

@YeasinSheikh it is from Dio library pub.dev/packages/dio#cancellation — user3808307
– user3808307, Commented Jul 30, 2021 at 21:19
@YeasinSheikh github.com/flutterchina/dio/blob/master/dio/lib/src/… — user3808307
– user3808307, Commented Jul 30, 2021 at 21:42

Phil Cazella · Accepted Answer · 2021-08-01 21:25:38Z

2

+50

The error is telling you that the CancelToken class cannot be converted to JSON directly. Your options are:

Build a service class that converts your KeyState class into a JSON representation manually.
Create an extension method for the CancelToken class in your project, which adds the fromJson and toJson methods to it. https://dart.dev/guides/language/extension-methods
Fork the code from Github, add the conversion methods to the CancelToken class yourself, and reference your repo in your pubspec.yaml file. (also, submit a pull request to merge your changes into the original repo)

You will also need to add similar conversion methods for dependant types like DioError, RequestOptions, Response.

edited Aug 1, 2021 at 21:25

answered Aug 1, 2021 at 21:19

Phil Cazella

8545 silver badges11 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

user3808307 Over a year ago

Yes, I understand, I don't know how to do it. Can you please share how to Build a service class that converts your KeyState class into a JSON representation manually.

user3808307 Over a year ago

can you please post an example of number 2? thank you

Gladwell Ndlovu Over a year ago

Any workaround on this?

AceP Over a year ago

this is an example of a JsonConverter service: stackoverflow.com/a/69749532/13801829

Collectives™ on Stack Overflow

Generate fromJson code for non valid json type

1 Answer 1

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related