Cereal offers no-boilerplate JSON serialization for Dart objects. It does this with Dart's new extension methods & code generation.

import 'package:cereal/cereal.dart';

// The code generator will create this file,
// but you do have to type this file name in first.
part 'my_file.g.dart';

@cereal
class Struct {
    final int foo;
    final String bar;

    Struct({this.foo, this.bar});
}

The code generator will generate a Struct.toJson, as well as a json.decodeStruct method on the json object in dart:convert.

import 'dart:convert';

import 'src/my_file.dart';

void main() {
    json.encodeStruct(Struct(
        foo: 0, 
        bar: 'hello world',
    ));

    final struct = json.decodeStruct(
        '{"foo": 0, "bar": "hello world"}',
    );
}

Whenever your Struct class is in-scope, the appropriate serializer and deserializer methods will also be available. This is made possible by generated Dart class extension methods.

To add Cereal to your project, change your pubspec.yaml like so:

# You need at least Dart 2.6.0, which launched extension methods.
environment:
  sdk: '>=2.6.0 <3.0.0'

dependencies:
  # Depend on some version of cereal.
  cereal: ^0.0.2

dev_dependencies:
  # Depend on some version of cereal_generator
  cereal_generator: ^0.0.2
  # build_runner will run the code generator.
  build_runner: ^1.0.0

From there, you can run pub get or flutter pub get and start annotating data classes as @cereal.

To generate the json serializers, run the following:

pub run build_runner build

or

flutter pub run build_runner build